PTO Installation And Applications Instruction{1165} Caterpillar

Safety

General Hazard Information

Do not operate or work on the engine and/or PTO unless you have read and understand the instructions in this Manual. Failure to follow the instructions could result in personal injury.

Attach a SEHS7332, DO NOT OPERATE tag or similar warning tag to the start (ignition) switch or PTO controls before performing maintenance or repairing the engine and/or PTO. Do not allow unauthorized personnel on, around or in the vehicle when maintenance or repair is being performed.

Do not start or attempt to start the engine, or move any of the controls, if there is a warning tag attached to the start (ignition) switch or PTO controls.

Do not attempt repairs you do not understand, refer to your dealer.

Start the engine only from the operator's station (cab). Never short across the starting motor terminals or the batteries. This could bypass the engine neutral start system as well as damage the engine electronics.

Never attempt adjustments or repairs while the engine is running unless otherwise specified in this Manual. Guards should be in place whenever repairs are performed.

Do not climb on or jump off of the vehicle when performing repairs, use an adequate ladder.

Do not disable or bypass automatic alarm or shut down circuits. They are provided to prevent personal injury and engine damage. Make provisions for shutting off the fuel supply to stop the engine in the event of an engine overspeed.

If Engine Monitoring is programmed to Derate, and one of the monitored conditions is exceeded, the engine will derate (run at a lower rating and rpm than normal). This should be considered especially if the engine is losing power while in PTO mode. Operation in this condition could present a p problem for the vehicle or risk to the operator.

For specific topics regarding proper operator instructions and information for your truck configuration, refer to "Recommended Information for Driver/PTO Operators" on page 9 in this Manual. Refer to the Operation & Maintenance Manual for your truck engine for additional safety and hazard information.

Welding on a Vehicle Equipped with a 3100 HEUI Engine

Before welding on a vehicle equipped with an electronic engine, the following precautions should be observed.

1) Disconnect all cables connected to the vehicle batteries.

2) Disconnect both ECM Connectors (Engine Harness - J2/P2 and Vehicle Harness - J1/P1).

3) Do not use the ECM or Engine Ground Stud for grounding of the welder.

4) Locate the welding ground cable as close as possible to the welding area.

Advantages of "Dedicated PTO"

Background

The 3100 HEUI Diesel Truck Engine provides several options to enhance vehicles requiring control of engine speed for vocational applications. The options include applications for Cement Mixers, Refuse Packers, Bulk Haulers, Utility Trucks, Fire Trucks, or an application requiring control of engine rpm for operating specialized equipment. Seven "Dedicated PTO" parameters and three inputs are included. Using these features provides a significant increase in engine capability and usage for these special applications.

Compared to mechanically controlled engines, the features available with the electronically controlled 3100 HEUI Diesel Truck Engines eliminate mechanical control cables, air cylinders, electric solenoids, and associated linkages and connections. Compared to some electronically controlled engines, the features available with the 3100 HEUI Diesel Truck Engines provide a cleaner installation and leave the cab Cruise Control Switches untouched for over-the-road use.

* Features

* Reduces or eliminates alteration of cab wiring.

* Unnecessary to alter cab throttle position system to disable cab throttle/accelerator pedal.

* One speed control (programmed low idle to PTO preset Set Speed) for engine rpm with one circuit.

* Two speed control (programmed low idle, PTO preset Set Speed, and PTO Top Engine Limit) with three circuits.

* Remote second throttle position sensor for variable speed engine rpm control.

* Lower engine set speeds can be used reducing engine noise levels during PTO operation compared to mechanical engines.

* Customer Programmable Parameter Options

* PTO Configuration - determines how ECM interprets inputs used for Dedicated PTO.

* PTO Top Engine Limit - Top RPM Limit for PTO.

* PTO Engine RPM Set Speed - provides PTO engine rpm set point for one or two speed control.

* PTO to Set Speed - requires only one circuit to provide one speed control.

* PTO Cab Throttle RPM Limit - provides parameter to limit cab throttle position sensor during PTO operation.

* Torque Limit - reduces engine torque during PTO operation or when Torque Limit Switch is ON.

* PTO Vehicle Speed Limit (AUG96 and later Personality Modules)

Idle/PTO Mode Vehicle Speed Limit (JUL96 and earlier Personality Modules) - determines the vehicle speed operating range during PTO operation.

* Idle/PTO RPM Ramp Rate - determines the rate of engine rpm acceleration/deceleration for PTO operation.

* Idle/PTO Bump RPM - determines the amount of rpm change when the Set/Resume Switch is toggled.

* Additional Features

* When PTO On/Off circuit is in the ON position, ECM controlled engine exhaust brakes are disabled.

* When PTO On/Off circuit is in the ON position, the Idle Shutdown feature is disabled.

* Prevents the cab clutch and service brake inputs from disengaging an engine set speed for slow moving operations requiring engine rpm control from the cab, such as curb pouring cement trucks.

* Two-pin connector and wiring standard on all 8WL engines (GMC & Chevrolet) for PTO On/Off Switch and PTO Interlock Switch(es) circuit installation.

Figure 1 - PTO Configuration Truck Diagrams

Power Take-Off (PTO) Definition

Power Take-Off (PTO) as referred to in this manual is engine rpm control initiated through a dedicated PTO On/Off circuit connected to the ECM Multi-Function Input #1 (pin-8 of the ECM Vehicle Harness Connector J1/P1). Engine rpm control initiated through the Cruise Control On/Off circuit will be referred to as idle. Engine rpm control initiated through the Fast Idle Enable Switch is referred to as Fast Idle.

Four Programmable PTO Configurations

* Off - Dedicated PTO parameter functions are not available.

* Cab Switches - uses cruise control Set/Resume switch with separate PTO On/Off switch to control engine rpm.

* Remote Switches - uses remote Set/Resume switch with separate PTO On/Off switch to control engine rpm.

* Remote Throttle - uses remote throttle position sensor and remote Set/Resume switch with separate PTO On/Off switch to control engine rpm.

One Speed Control with One Circuit

* Provides an optional PTO Set Speed for those applications where only one speed above low idle is required.

* Required components are a PTO On/Off Switch, PTO Interlock Switch(es) and PTO Switch On Lamp(s).

One Speed Control with One Circuit (8WL Only - GMC & Chevrolet)

* A two-pin connector and wiring are standard on all 8WL engines for connection of the Remote PTO On/Off Switch and PTO Interlock Switch(es) circuit.

Two Speed Control with Three Circuits

* Two speed control of engine rpm with PTO preset Set Speed and PTO Top Engine Limit above low idle.

* Required components are a PTO On/Off Switch, PTO Interlock Switch(es), a PTO Set/Resume Switch and PTO Switch On Lamp(s).

Variable Speed Control using Remote Switches

* Required components are a PTO On/Off Switch, PTO Interlock Switch(es), a PTO Set/Resume Switch and PTO Switch On Lamp(s).

Variable Speed Control using a Remote, Second Throttle Sensor Input

* Required components are a PTO On/Off Switch, PTO Interlock Switch(es), a PTO Set/Resume Switch, a Relay, and Hand Throttle or Accelerator Pedal assembly with Caterpillar Throttle Position Sensor.

Engine RPM Control Using Switches versus Control Using a Throttle Position Sensor

* Use switches to control engine rpm if the engine will be operating at specific engine rpm points (i.e. low idle, 1200 rpm, and 1600 rpm). Switches are also recommended if the driver/PTO operator will be frequently varying engine rpm and if the driver/PTO operator will not have a hand or foot free to operate the throttle control/accelerator pedal.

Fast Idle Option - One Speed Control with One Circuit

* Provides a second optional set speed for those applications where two speeds above low idle is required (standard on GM vehicles with a default speed of 1000 rpm).

* Required components are a momentary Fast Idle Enable Switch and a Fast Idle Enabled Lamp (standard on GM vehicles).

Fast Idle Option - Two Speed Control with One Circuit

* Provides a second optional set speed for those applications where two speeds above low idle are required (standard on GM vehicles with a default speed of 0 rpm).

* Requires AUG96 or later Personality Module.

* Required components are a momentary Fast Idle Enable Switch and a Fast Idle Enabled Lamp (standard on GM vehicles).

Differences Between Fast Idle and Dedicated PTO

* Fast Idle operation is intended for In-Cab control of engine speed. Dedicated PTO can be set up for In-Cab or remote control of engine speed.

* Fast Idle requires a single momentary switch to adjust the engine speed. Dedicated PTO can be as simple as a single two-position switch (On or Off, NOT Momentary), or more complex requiring combinations of two-position switches and momentary switches, or a remote throttle position sensor.

* Dedicated PTO provides programmable cab throttle position sensor engine rpm limits and programmable torque limits. These features are not available for Fast Idle control.

* Because Fast Idle requires a momentary switch it can not be used for systems requiring two-position switches, where these switches are hydraulically or air operated, or position limit switches integrated into the PTO operation.

* Dedicated PTO provides a programmable engine rpm ramp rate. The Fast Idle rpm ramp rate is fixed and can not be adjusted.

Standard Features on GMC and Chevrolet Medium Duty Trucks (8WL Only)

* Two-pin connector and wiring is standard on all 8WL engines (GMC & Chevrolet) for PTO On/Off Switch and PTO Interlock Switch(es) circuit installation.

* A Fast Idle Enable Switch is a dash mounted switch standard in all GMC and Chevrolet Medium Duty Trucks (8WL engines).

Installing Switches and Components in Vehicles Equipped With 3100 HEUI Engines

Before attempting to install the switches and program the parameters for the vehicle application, ensure everyone understands how the engine and components will be used during the PTO operation. The questionnaire on the following page will help the installer and the truck owner/driver/PTO operator understand the options available and determine what to install. Refer to "Programmable Parameters" on page 17.

Questions 1 thru 8 should be asked before starting the installation procedure. The remaining questions may be asked after the installation is completed to fine tune the programming and other system components. Refer to programmed parameters information described on the "Driver/PTO Operator Programmed Parameter Information Sheet" on page 14. Refer to SEBU6885, Operation & Maintenance Manual or LEXT6495, Specing Caterpillar Electronic Truck Engines, for additional information.

Recommended Information for Driver/PTO Operators

After the Installation is Completed

When the installation is complete, please complete the "Installation Questionnaire" on page 10. "Driver/PTO Operator Programmed Parameter Information Sheet" on page 14, "Driver/PTO Operator Instructions" on page 15, "Truck Installation Diagram - Switches and Components" on page 16 and "Programmable Parameters" on page 17, to explain the installation to the truck owner/driver/PTO operator, and leave them in the vehicle glove box. This will allow the driver/PTO operator(s) to review the truck set up, and also help the mechanic/service technician understand how to troubleshoot any suspected problems relating to the installation.

Installation Questionnaire

Installation and Programming Based on Questionnaire Response.

Driver/PTO Operator Programmed Parameter Information Sheet

Driver/PTO Operator Instructions

Truck Installation Diagram - Switches and Components

1. Diagram the switches, sensors, and lamps used, and their locations. Refer to the Figure 1 - "PTO Configuration Truck Diagrams" on page 7, PTO Configuration Truck Diagrams, in this manual for examples.

2. Provide a copy of the appropriate wiring diagrams, worksheets, etc from this manual which illustrates the specific installation.

Figure 2 - Installed Location of Switches and Components

Programmable Parameters

Understanding Programmable Engine RPM Limits

There are four programmable engine rpm limits available with the 3100 HEUI electronic system.

* Top Engine Limit: This rpm limit is used while driving the vehicle over the road. It determines the maximum rpm the engine will achieve when the PTO On/Off Switch is in the OFF position.

* Idle RPM Limit: This is the maximum engine rpm limit if the engine rpm is established using the Cruise Control On/Off Switch and the Cruise Control Set/Resume Switch. The programmable range is from 700 to TEL rpm (in one rpm increments). The minimum programmable Idle RPM Limit is determined by the programmed Low Idle RPM. The maximum programmable Idle RPM Limit is limited by the programmed Top Engine Limit.

* PTO Top Engine Limit: This is the maximum engine rpm limit if the rpm is established using the Dedicated PTO circuits. This limit has a programmable range from 700 to TEL rpm (in one rpm increments). The minimum programmable PTO Top Engine Limit is actually determined by the programmed Low Idle RPM. The maximum programmable PTO Top Engine Limit is TEL rpm.

* Fast Idle Engine RPM Limit: The Fast Idle RPM Limit is the maximum RPM Set Speed using the Fast Idle Enable Switch. The programmable range is 700 rpm to 1600 rpm if the Personality Module is JUN95 or earlier. If the Personality Module is JUL95 or later the range is 700 rpm to Top Engine Limit rpm. The operator can override the programmed Fast Idle RPM by depressing the accelerator pedal and depressing/toggling the Fast Idle Enable Switch when the engine is at the desired rpm. This rpm would then be the Fast Idle RPM until the engine is shut down.

The following Tables (1 thru 11) define a sequence of events. They begin with the Driver/PTO Operator Action using Controlling Equipment positions. These positions produce Engine RPM Results within specific programmed limits. The Cruise On/Off, PTO On/Off, Set/Resume, Fast Idle, and Accelerator Pedal are all shown to provide a demonstration of how each system interacts. Most systems will require only some of these components.

Fast Idle For In Cab Control of PTO Operations

Table 2 illustrates engine speed control using the Fast Idle Enable Switch. The Fast Idle Enable Switch is a dash mounted switch standard in GMC and Chevrolet Medium Duty Trucks (8WL engines), optional in all other chassis. The Fast Idle Engine RPM parameter provides one set speed above Low Idle operation. The Fast Idle Engine RPM #2 parameter provides two set speeds above Low Idle. The Fast Idle Engine RPM #2 parameter requires AUG96 or later Personality Module.

NOTE: Fast Idle Engine RPM programmed value can be overridden using the cab throttle and once it is overridden the new value remains in effect until the ignition key switch is turned OFF. Refer to Frame 5 in Table 2. Fast Idle Engine RPM #2 programmed value can not be overridden.

PTO Engine RPM Set Speed

This parameter is useful only if one or two specific engine rpm's above low idle are required when the PTO On/Off switch is in the ON position. Program this parameter to the same value as the PTO Top Engine Limit if ONLY one specific engine rpm above low idle is required.

this parameter determines the engine rpm the engine will advance to when the PTO On/Off switch is turned to the ON position, and the PTO to Set Speed Parameter is programmed to YES. If PTO to Set Speed is programmed to NO, this speed can be achieved using the RPM Increase/RPM Decrease (Set/Resume) Switch.

NOTE: The PTO Engine RPM Set Speed parameter programming can override the Idle/PTO Bump RPM parameter for PTO. If PTO Engine RPM Set Speed is programmed above 0 rpm, the Set/Resume inputs function as RPM Increase/RPM Decrease instead of Set/Resume when the PTO On/Off switch is ON.

Table 3 illustrates PTO operation with two specific rpm's above low idle. It also provides an example of the PTO Engine RPM Set Speed parameter for applications requiring engine operation at low idle, an intermediate rpm, and the PTO Top Engine Limit.

Table 4 illustrates PTO operation with one specific rpm above low idle. Refer to Table 5 on page 27 for an example of the PTO to Set Speed parameter.

PTO to Set Speed

Program this parameter to YES to have engine rpm accelerate to the PTO Engine RPM Set Speed when the PTO On/Off circuit is ON. This is useful for those applications requiring only one specific engine rpm above low idle, because only one circuit is required.

Programmable Torque Limit

Programming this parameter provides an engine torque limit for PTO operation or other special situations. The programmable range for this parameter is 100 to 2000 lb ft in 1 lb ft increments (136 to 2720 N·m in 1 N·m increments). Programming the Torque Limit above the rated torque of the engine will not provide additional torque. The engine will operate using its normal torque curve whenever the normal torque is less than the programmed value of the Torque Limit.

Table 6 and Table 7 demonstrate the Torque Limit for PTO use, and when PTO is OFF. Be aware that the programmed Torque Limit will apply whenever PTO On/Off is ON, also when the Torque Limit Switch is ON, which occurs only when the PTO On/Off switch is OFF. (If PTO Configuration is programmed to Cab Switches, refer to Figure 29 and Figure 30 - on page 51 for 8WL engines or Figure 31 and Figure 32 - on page 52 for 1WM & 4ES engines. If PTO Configuration is programmed to Remote Switches, refer to Figure 33 and Figure 34 - on page 53 for 8WL engines or Figure 35 and Figure 36 - on page 54 for 1WM & 4ES engines). Typically, the Torque Limit switch illustrated will be part of the system requiring the torque limit. For example, a switch in the transmission for deep reduction gears is a transmission system requiring the torque limit. Program the Torque Limit to the rated torque of the device it is protecting.

NOTE: The programmed torque level is an estimate. To achieve precise torque limiting, a chassis dynamometer may be required.

Engine Speed (RPM)
Figure 3 - Programmable Torque Limit

PTO Cab Throttle RPM Limit

This parameter applies only when PTO Configuration is programmed to Cab Switches. For PTO Configuration programmed to Remote Switches, the cab is always limited to low idle. When the PTO On/Off circuit is ON, the cab throttle position sensor is limited to the value of the PTO Cab Throttle RPM Limit. This is useful for applications with equipment that may be damaged by engine overspeed. This parameter has three programmable choices. They are Low Idle, Top Engine Limit, or PTO Top Engine Limit.

1. If programmed to Low Idle, the engine will not exceed the programmed Low Idle if the accelerator pedal is depressed with the PTO On/Off circuit ON (the accelerator pedal is ignored).

2. If programmed to Top Engine Limit, depressing the accelerator pedal will allow the engine to achieve the programmed Top Engine Limit when the PTO On/Off circuit is ON.

3. If programmed to PTO Top Engine Limit, depressing the accelerator pedal will allow the engine to reach the programmed PTO Top Engine Limit when the PTO On/Off circuit is ON.

Three examples are illustrated in Table 8, Table 9 and Table 10 to describe each of the three options (Low Idle, Top Engine Limit, and PTO Top Engine Limit) for this parameter.

Idle/PTO RPM Ramp Rate

This parameter determines the rate of acceleration and deceleration of the engine when the engine rpm is changing because of actuation of the Set/Resume switch, Idle/PTO Bump RPM, PTO to Set Speed, or the PTO Engine RPM Set Speed parameters. This mode or condition does not apply to engine rpm acceleration and deceleration due to a throttle position sensor.

The parameter is programmed in one rpm per second increments from 5 to 1000 rpm per second. This parameter should be programmed to match the application to provide reduced cycle times for those applications where a reduced cycle time is critical. Programming excessive ramp rates may stress PTO driven equipment.

Idle/PTO Bump RPM

Program this parameter to change the engine rpm (increase or decrease) when the Set/Resume switch is toggled. If the PTO Engine RPM Set Speed is programmed to one rpm or above, the parameter is overridden.

For example, the Idle/PTO Bump RPM would only apply to engine Idle, when the Cruise Control On/Off Switch is in the ON position, the PTO On/Off circuit is OFF, and the Cruise Control Set/Resume Switch is toggled.

NOTE: This parameter does not apply to Engine RPM Set using the Fast Idle Enable Switch. The Fast Idle RPM is not set or changed with the Cruise Control Set/Resume Switch.

Idle/PTO Vehicle Speed Limit - JUL96 and earlier Personality Modules

This parameter applies to setting an engine rpm using the PTO On/Off or Fast Idle Enable switches. Programmable range is 1 to 15 mph in one mph increments (1 to 24 km/h in one km/h increments). Program this parameter to 1 mph (km/h) if vehicle movement must not occur during PTO operation. The Idle/PTO Mode Vehicle Speed Limit determines the vehicle speed range which the engine control will allow. The setting of an engine rpm, and the vehicle speed limit (if exceeded), will cause disengagement of an active set rpm.

PTO Vehicle Speed Limit - AUG96 and later Personality Modules

This parameter applies to setting an engine rpm using the PTO On/Off switch. Programmable range is 1 to 127 mph in one mph increments (2 to 204 km/h in one km/h increments). Program this parameter to 1 to disable PTO Set RPM while vehicle is moving. The PTO Mode Vehicle Speed Limit determines the PTO vehicle speed range the engine control will allow. The setting of an engine rpm, and the vehicle speed limit (if exceeded), will cause disengagement of an active set rpm.

NOTE: If the PTO Vehicle Speed Limit parameter is used to avoid vehicle speed circuit disconnection because the PTO is transmission driven, parking brake switch and neutral switch interlocks are required in the PTO On/Off Switch circuit. Refer to Figure 37 on page 55.

Cruise/Idle/PTO Switch Configuration

This parameter will determine the Accel and Decel function of both the Cruise Control On/Off and PTO On/Off controlled Set/Resume switch when the switch is toggled to bump up the rpm or, held in position for a constant acceleration. The Caterpillar Factory default is Set-Accel/Resume-Decel. This can be changed to Set-Decel/Resume-Accel using a Caterpillar Electronic Service Tool.

NOTE: When PTO On/Off Switch is in the ON position, and PTO Engine RPM Set Speed is programmed to one rpm or above, the Set Switch serves as RPM Increase and the Resume Switch serves as RPM Decrease regardless of the programmed Cruise/Idle/PTO Switch Configuration.

Engine Monitoring

Caterpillar 3100 HEUI Diesel Truck engines have an engine monitoring feature available. The engine will respond to high coolant temperature depending upon how this parameter is programmed. The parameter can be programmed to Off, Warning or Derate. Refer to the engine Operation & Maintenance Manual for additional information regarding this feature.

Programming the Parameters

Programming the parameters requires an Electronic Service Tool, and if programmed, Customer Passwords. Availability of some of the parameters depends upon the programming of other parameters. Before attempting to program any of the Dedicated PTO Parameters, program the PTO Configuration Parameter first. Failure to program the PTO Configuration Parameter first will cause the remaining Dedicated PTO Parameters to indicate Not Installed from the Electronic Service Tool Status Screen.

Programming Provisions

The following parameters or their operation are affected by other parameter settings as indicated.

* PTO Configuration-All "Dedicated PTO Parameters" require the PTO Configuration Parameter to be programmed first (from PTO On/Off circuit OFF position) before any other parameter can be programmed to enable/allow programming other "Dedicated PTO Parameters".

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NOTICE
If PTO Configuration is programmed to Remote Throttle, a relay (or other switch) is required to switch between the cab throttle position and remote throttle position inputs. The cab throttle must be switched out of the system circuit when the remote throttle is used and remote throttle must be switched out of the system circuit when the cab throttle is used. Refer to Figure 25 and Figure 26 - on page 49 for 8WL engines on Figure 27 and Figure 28 - on page 50 for 1WM & 4ES engines.

* PTO Top Engine Limit-this parameter should be programmed above the programmed Low Idle.

* PTO Engine RPM Set Speed-programming this parameter overrides/disables the Idle/PTO Bump RPM for PTO operation.

* PTO to Set Speed-requires PTO Engine RPM Set Speed programmed to an engine rpm above low idle.

* PTO Cab Throttle RPM Limit-applies only if the PTO Configuration is programmed to Cab Switches. If the PTO Configuration is programmed to Remote Switches, the cab throttle position sensor is always limited to low idle when the PTO On/Off circuit is ON.

* Torque Limit-the Torque Limit can be programmed to values above the Rated Torque of the engine, but doing so is meaningless - the Rated Torque of the engine is the maximum torque of the engine.

* Cruise/Idle/PTO Switch Configuration-if the PTO Engine RPM Set Speed parameter is programmed, the Set/Resume switch operates as an RPM Increase/RPM Decrease switch when the PTO On/Off switch is ON. Placing the switch in the Set position will indicate to the ECM a desire to increase engine rpm. Placing the switch in the Resume position will indicate to the ECM a desire to decrease engine rpm.

Component Installation

Figure 4 - 3100 HEUI Electronic Control Module

Installation Considerations

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Preventing unwanted operation of the engine requires careful installation of interlock switches in the system. These interlocks must prevent operation of the engine rpm PTO until the PTO operator is expecting it and is prepared.

* PTO Switch On Lamp

The PTO Switch On Lamp should be installed in the cab and at the PTO operating station (if outside of the cab). This lamp will provide indication to the driver/PTO operator when the PTO On/Off circuit is ON and must be connected to the PTO On/Off switch to activate.

Refer to the appropriate diagrams for the application. If PTO Configuration is programmed to Cab Switches, refer to Figure 13 and Figure 14 - on page 43 for 8WL engines or Figure 15 and Figure 16 - on page 44 for 1WM & 4ES engines. If PTO Configuration is programmed to Remote Switches, refer to Figure 17 and Figure 18 - on page 45 for 8WL engines or Figure 19 and Figure 20 - on page 46 for 1WM & 4ES engines. If PTO Configuration is programmed to Remote Throttle, refer to Figure 25 and Figure 26 - on page 49 for 8WL engines or Figure 27 and Figure 28 - on page 50 for 1WM & 4ES engines.

* PTO Configuration Programmed to Remote Switches or Remote Throttle

It is important to remember that the cab throttle position sensor (if properly wired for Remote Throttle configuration), clutch switch, service brake switch, and cruise control switches are all ignored when the PTO On/Off circuit is ON if the PTO Configuration is programmed to Remote Switches or Remote Throttle. A PTO Switch On Lamp is recommended in both the cab and at the remote station to indicate when the PTO On/Off circuit is ON.

A Parking Brake Switch and/or Transmission Neutral Switch will cause the engine to return to low idle rpm if someone tries to move the vehicle while the PTO operator is at the remote PTO location.

The Idle/PTO Vehicle Speed Limit should also be programmed to the minimum, 1 mph (1 km/h), to cause the engine to return to low idle in PTO if the vehicle is moved.

* Engine Shutdown Switch

If an engine shutdown switch is desired, this switch should be connected to a Normally Closed Relay as shown in the schematic below. The actual location of the switch should be readily accessible to the PTO operator during PTO operation.

Figure 5 - Engine Shutdown Switch Wiring Diagram - 1WM1-UP & 4ES1-UP

Figure 6 - Engine Shutdown Switch Wiring Diagram - 8WL1-UP

Component Electrical Specifications

* Switch Electrical Specifications

The switch contact plating should not corrode or oxidize. Gold plated contacts are recommended. All switches should be environmentally sealed and protected as required by the application.

The applied voltage to switches will normally not exceed 11.5 Volts. Normal current draw through the switches will not exceed 0.0065 A (6.5 mA).

Contact "chatter" and momentary opening or closing should not exceed 0.1 seconds (100 milliseconds) in duration. The switches should not open or close due to vibration or shock normally found in the application. Closure of an installed switch must short circuit to the input the PTO Sensor Common (pin-30, ECM Vehicle Harness Connector J1/P1).

* Voltage thresholds measured at the ECM

- Voltage-In-Low (less than 0.8 Volts) - When switch contacts close (switch closure), ground potential difference, switch voltage drop, and wiring harness voltage drop results must be less than 0.8 Volts between the respective control input and PTO Sensor Common (P1 pin-30).

- Voltage-In-High (greater than 9.0 Volts) - When switch contacts open, pin to pin leakage paths in connectors, harnesses, and switches must NOT result in an effective resistance of less than 5,000 Ohms from the respective control input to PTO Sensor Common (P1 pin-30).

NOTE: OEM installed switches used as inputs to the ECM must not be connected to the vehicle or cab ground. OEM installed switches must be grounded to the ECM PTO Sensor Common using a dedicated return line to ECM Vehicle Harness Connector P1 pin-30.

Selecting Switch Type

The type of switch required depends upon the type of application required. The Set/Resume or RPM Increase/RPM Decrease Switch is typically a three position momentary switch with a spring return to the OFF position.

The PTO On/Off Switch can be an On/Off, two position switch, either manually, air or hydraulically actuated.

The PTO Interlock Switches are typically air actuated, normally closed switches connected into the Parking Brake air lines, or the Transmission air lines. These or all switches may be hydraulically controlled switches or limit switches. All switches located outside the cab should be environmentally sealed and protected.

* Switches Available from Caterpillar

A 112-4073 Switch Assembly is available. The switch is a single pole, single throw, air actuated type.

Figure 7 - 112-4073 Switch Schematic

Throttle Position Sensor Electrical Specifications

Figure 8 - Caterpillar 110-8190 Throttle Position Sensor (12V)

Caterpillar requires the 110-8190 Throttle Position Sensor. The 110-8190 is supplied with a Deutsch HD plug connector (HD16-3-96S, Caterpillar Part Number 8T8731). The connecting harness will require a Deutsch HD receptacle connector (HD14-3-96P, Caterpillar Part Number 8T8732).

NOTE: Do not connect a 110-8190 Throttle Position Sensor to the ECM 8 Volt supply. It must be connected/powered by 12 Volt battery voltage.

Mounting the Throttle Position Sensor

The 110-8190 Throttle Position Sensor can be attached to either an accelerator pedal assembly (contact the vehicle OEM for parts) or a 107-2281 PTO Throttle Assembly (or Williams part number 131446). The PTO Throttle Assembly does not include handle and may be used in applications where a mechanical linkage is required.

Figure 9 - Accelerator Pedal/Throttle Assembly Options

Harness Specifications

The installed harness should be protected from the environment using corrugated plastic conduit or other means. All wire should be 18 AWG or larger, SAE J1128 Type GXL, TXL or equivalent. The acceptable range for wire insulation outside diameter is 2.54 to 3.43 mm (0.10 to 0.135 inches) for the Deutsch 40-Pin ECM Vehicle Connector. All ring terminals and splices connected to the harness routing to the engine ECM must be sealed using Raychem ES2000 shrink tube or equivalent.

Figure 10 - Connectors and Connector Components

Installation of Fast Idle Configuration

The diagrams on this page illustrate the location of each of the components as well as the wiring diagram for the Fast Idle.

Fast Idle Configuration

Figure 11 - Truck Diagram - Fast Idle

Figure 12 - Wiring Diagram - Fast Idle

Installation for Three PTO Configurations

The diagrams on the following pages illustrate the possible location of each of the components as well as wiring diagrams for various PTO Configurations.

Cab Switches Configuration - 8WL Only (GMC & Chevrolet)

Figure 13 - Truck Diagram - Cab Switches - 8WL Only

Figure 14 - Wiring Diagram - Cab Switches - 8WL Only

Cab Switches Configuration - 1WM & 4ES

Figure 15 - Truck Diagram - Cab Switches - 1WM & 4ES

Figure 16 - Wiring Diagram - Cab Switches - 1WM & 4ES

PTO Configuration Cab Switches - This Configuration provides the advantage of not requiring splicing into the existing cab wiring. The Cruise Control Set/Resume Switch is used for PTO Operation, Cruise Control and Idle. The function of the Set position and Resume position is determined by the programming of the PTO Engine RPM Set Speed, Cruise/Idle/PTO Switch Configuration, and Idle/PTO Bump RPM parameters.

If the PTO Engine RPM Set Speed is programmed above 0 rpm, the Set position becomes RPM Increase, the Resume position becomes RPM Decrease. If the PTO Engine RPM Set Speed is programmed to 0 rpm, the Set position provides either the Accel or Decel function and the Resume position provides either Decel or Accel with a programmable bump rpm determined by the Idle/PTO Bump RPM parameter.

NOTE: If the Transmission Style is programmed to Auto w/2 Brake Sw, Auto w/o 2 Brake Sw, MT/AT w/2 Brake Sw, or MT/AT w/o 2 Brake Sw and the PTO Configuration is programmed to Cab Switches the Neutral Switch input (J1/P1 pin-38), indicating the transmission is not in gear, is required for PTO operation.

Remote Switches Configuration - 8WL Only (GMC & Chevrolet)

Figure 17 - Truck Diagram - Remote Switches - 8WL Only

Figure 18 - Wiring Diagram - Remote Switches - 8WL Only

Remote Switches Configuration - 1WM & 4ES

Figure 19 - Truck Diagram - Remote Switches - 1WM & 4ES

Figure 20 - Wiring Diagram - Remote Switches - 1WM & 4ES

PTO Configuration Remote Switches - The PTO Set/Resume Switch is used for PTO Operation in the above diagram. The function of the Set position and Resume position is determined by the programming of the PTO Engine RPM Set Speed, Cruise/Idle/PTO Switch Configuration, and Idle/PTO Bump RPM parameters.

If the PTO Engine RPM Set Speed is programmed above 0 rpm, the Set position becomes RPM Increase and Resume becomes RPM Decrease. If the PTO Engine RPM Set Speed is programmed to 0 rpm, the Set position provides either the Accel or Decel function and Resume either Decel or Accel with a programmable bump rpm determined by the Idle/PTO Bump RPM parameter.

Remote Switches with One Speed Above Low Idle - 8WL Only (GMC & Chevrolet)

Figure 21 - Truck Diagram - Remote Switches with One Speed Above Low Idle - 8WL Only

Figure 22 - Wiring Diagram - Remote Switches - 8WL Only

Remote Switches with One Speed Above Low Idle - 1WM & 4ES

Figure 23 - Truck Diagram - Remote Switches with One Speed Above Low Idle - 1WM & 4ES

Figure 24 - Wiring Diagram - Remote Switches - 1WM & 4ES

PTO Configuration Remote Switches with one programmed speed above low idle

The PTO Set/Resume Switch is NOT used for PTO Operation. For the above circuit, PTO to Set Speed should be programmed to YES, and the PTO Engine RPM Set Speed must be programmed to the desired rpm.

Remote Throttle Configuration - 8WL Only (GMC & Chevrolet)

Figure 25 - Truck Diagram - Remote Throttle - 8WL Only

Figure 26 - Wiring Diagram - Remote Throttle - 8WL Only

Remote Throttle Configuration - 1WM & 4ES

Figure 27 - Truck Diagram - Remote Throttle - 1WM & 4ES

Figure 28 - Wiring Diagram - Remote Throttle - 1WM & 4ES

PTO Configuration Remote Throttle - For the above circuit, the ECM monitors the Remote Throttle Position Sensor when the PTO On/Off and PTO Interlock Switches are closed. The PTO Set Switch can be used to set engine rpm and the PTO Resume Switch is available to resume a previously set RPM. If the PTO Set Switch or PTO Resume Switch is held in position the switch will accel or decel from the current set speed based on customer specified parameter programming.

Cab Switches w/ Torque Limiting & Disabling Brake/Clutch Kickout - 8WL Only (GMC & Chevrolet)

Figure 29 - Truck Diagram - Cab Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 8WL Only

Figure 30 - Wiring Diagram - Cab Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 8WL Only

Cab Switches w/ Torque Limiting & Disabling Brake/Clutch Kickout - 1WM & 4ES

Figure 31 - Truck Diagram - Cab Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 1WM & 4ES

Figure 32 - Wiring Diagram - Cab Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 1WM & 4ES

Remote Switches w/ Torque Limiting & Disabling Brake/Clutch Kickout - 8WL Only (GMC & Chevrolet)

Figure 33 - Truck Diagram - Remote Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 8WL Only

Figure 34 - Wiring Diagram - Remote Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed Torque Limit - 8WL Only

Remote Switches w/ Torque Limiting & Disabling Brake/Clutch Kickout - 1WM & 4ES

Figure 35 - Truck Diagram - Remote Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed - 1WM & 4ES

Figure 36 - Wiring Diagram - Remote Switches with Torque Limiting and Disabling Brake/Clutch Kickout of PTO Set Speed Torque Limit - 1WM & 4ES

PTO Interlocks - Transmission Driven PTO (Any PTO Configuration)

Figure 37 - Wiring Diagram - Recommended PTO Switch On Circuit For Transmission Driven PTO - 8WL Only

Figure 38 - Wiring Diagram - Recommended PTO Switch On Circuit For Transmission Driven PTO - 1WM & 4ES

Torque Limit

* Cab Switches

The PTO Configuration Cab Switches is used in Figure 29 and Figure 30 - on page 51 for 8WL engines and Figure 31 and Figure 32 - on page 52 for 1WM & 4ES engines. The diagrams also include the ability to use a programmed Torque Limit when the PTO On/Off switch is in either the ON or OFF position. Torque Limit always applies when the PTO On/Off switch is in the ON position. The diagrams illustrate how to connect a second switch to provide the Torque Limit under other conditions when driving over the road and the PTO On/Off switch is in the OFF position. This is useful, for example, if the transmission provides deep reduction gears requiring reduced torque levels for the driveline.

* Remote Switches

The PTO Configuration Remote Switches is used in Figure 33 and Figure 34 - on page 53 for 8WL engines and Figure 35 and Figure 36 - on page 54 for 1WM & 4ES engines. The diagrams also include the ability to use a programmed Torque Limit when the PTO On/Off switch is in the ON or OFF position. If a Torque Limit is programmed, it always applies when the PTO On/Off switch is in the ON position. The diagrams illustrate how to connect a second switch to provide the Torque Limit under other conditions when driving over the road and the PTO On/Off switch is in the OFF position. This is useful, for example, if the transmission provides deep reduction gears requiring reduced torque levels for the driveline.

Interlock Sw#1 and Interlock Sw#2 should be actuate/switched at the same time into the positions shown in the diagrams. If the PTO On/Off Switch is OFF, the ECM considers connection of J1/P1 pin-32 to pin-30 (Torque Limit Switch closed and Interlock Sw#1 in lower position) as a request to limit torque to the programmed Torque Limit.

Brake/Clutch Disable Switch

* Cab Switches

The Brake/Clutch Disable Switch is intended for applications requiring mobile use of the vehicle with an engine rpm set, and NOT requiring the Brake or Clutch to disengage or disable the engine rpm set speed. This is useful for firetruck, cement pavement or curb pouring operations.

* Remote Switches

The Brake/Clutch Disable Switch is intended for applications requiring mobile use of the vehicle with an Idle engine rpm set (an rpm set using the Cruise Control On/Off and Cruise Control Set/Resume switches), and NOT requiring the Brake or Clutch to disengage or disable the engine rpm set speed. This is useful for firetruck, cement pavement or curb pouring operations.

Interlock Sw#1 and Interlock Sw#2 should be actuated/switched at the same time into the positions shown in the diagrams. If the PTO On/Off Switch is OFF, the ECM considers connection of J1/P1 pin-31 to pin-30 (Brake/Clutch Disable Switch closed and Interlock Sw #2 in lower position) as a request to prevent the disengagement of an Idle set speed. This feature applies only when the vehicle is below the programmable Idle/PTO Vehicle Speed Limit and an engine rpm is set.

For the PTO Configuration Remote Switches, the PTO Set/Resume Switch is used for PTO Operation in Figure 34 - on page 53 for 8WL engines and Figure 36 - on page 54 for 1WM & 4ES engines. The function of the Set position and Resume Position is determined by the programming of the PTO Engine RPM Set Speed, Cruise/Idle/PTO Switch Configuration, and Idle/PTO Bump RPM parameters. If the PTO Engine RPM Set Speed is programmed above 0 rpm, the Set position becomes RPM Increase and Resume becomes RPM Decrease. If the PTO Engine RPM Set Speed is programmed to 0 rpm, the Set position provides either the Accel or Decel function RPM Increase and Resume either Decel or Accel with a programmable bump rpm determined by the Idle/PTO Bump RPM parameter.

Idle Shutdown Disabled with PTO Switch On

Whenever the PTO On/Off Switch circuit is ON, the ECM disables the Idle Shutdown Timer to prevent unwanted shut downs while in PTO. If there is concern about the driver abusing the disabled Idle Shutdown, the PTO On/Off Switch or Interlocks should be arranged to make this more difficult. If possible, incorporate the PTO On/Off Switch into the PTO activation system.

NOTE: It is critical that the PTO operator using the vehicle know and understand how the PTO system is set up and operates.

Troubleshooting the PTO Installation

This procedure is intended to confirm the PTO switches, and PTO Throttle Position Sensor circuits in the vehicle are installed and operating correctly.

Diagnostic Codes

Functional Test