3176B INDUSTRIAL ENGINE ELECTRONIC MONITORING SYSTEM INCLUDES COMPUTERIZE Caterpillar

Industrial Engine Electronic Monitoring And Control System

Usage:

NOTE: Refer to SENR6498 Schematic foldout and SENR6597 Electronic Troubleshooting for additional information when performing the following procedures.

Vehicle Battery Circuit Requirements

Grounding

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NOTICE

Improper grounding will cause uncontrolled and unreliable circuit paths. Stray electrical currents can result in damage to the engine's crankshaft main bearings, crankshaft journal surfaces or other engine components, especially aluminum components. They can cause electrical noise that may degrade the performance of the vehicle's electronic control system, electrical communication equipment, and radio.

Proper grounding for vehicular and engine electrical systems is necessary for proper performance and reliability. The problems stated above are often difficult to diagnose and repair.

Starting Motor and Alternator

All ground paths must be capable of carrying any conceivable fault currents. An AWG #4 (or larger) cable is recommended between the engine ground stud and the vehicle frame (or starting motor negative post).

The wire size from a ground must be of adequate size to handle full alternator charging current. An AWG #4 (or larger) cable is recommended to handle alternator currents. For engines which have the alternator grounded to an engine component, the component MUST be electrically isolated from the engine and a ground strap must connect that component to the battery negative post.

A maximum of three (ring) terminals are to be connected to the engine ground stud to ensure ground connection integrity. More than three terminals can cause the stud to easily loosen.

NOTE: The ECM is capable of operating with a 12V or 24V battery system. CMS and EMS modules have a power supply range of 18 to 24 volts.

Two required terminals are determined by Caterpillar.

1) engine ground stud to vehicle (-)Battery connection and ...

2) engine ground stud to ECM (-)Battery connection.

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NOTICE

The cab must not be grounded to the engine ground stud because noise transients (affecting control system performance) can be introduced.

Caterpillar recommends splicing like wire sizes together as a method of reducing ring terminal congestion at the engine ground stud.

Engine ground stud to starting motor to (-)Battery connection.

Electrical Power Supply Connections To ECM

Vehicle Battery Circuit Requirements and Considerations

* Grounding

Proper grounding for vehicle and engine electrical systems is necessary for proper performance and reliability. Improper grounding results in unreliable electrical circuit paths. Stray electrical currents can damage main bearings, crankshaft journal surfaces and aluminum components. They can also cause electrical noise degrading the performance of the control system, vehicle systems, and radio. These problems are often very difficult to diagnose and repair.

All ground paths must be capable of carrying any conceivable fault currents. An AWG #4 or larger cable is recommended between the engine ground stud and the frame or starting motor negative post. AWG #4 wire is recommended to handle alternator currents. A maximum of three ring terminals are to be connected to the engine ground stud to ensure ground connection integrity.

Ground Stud to Starting Motor to Battery

Two of these ground stud connections have already been defined by Caterpillar; the stud to vehicle (-)Battery connection and the stud to ECM (-)Battery connection.

More than three terminals can cause the stud to loosen too easily. The vehicle cab must not be grounded to the cylinder head ground stud because it can introduce noise transients affecting control system performance. Caterpillar recommends splicing like size wires together as a method of reducing ring terminal congestion at the ground stud.

* Electric Starting Motor Equipped Vehicles

Ground Stud Connection to (-)Battery - To ensure proper functioning of the vehicle and engine electrical systems, there must be a direct wire path from the engine ground stud to the battery negative post.

Caterpillar prefers this connection route through the starting motor negative post. (Refer to illustration Ground Stud to Starting Motor to Battery). A connection to a main frame rail ground can also be used as described below for air starting motor equipped vehicles.

Ground Stud to Frame Rail to Battery

* Air Starting Motor Equipped Vehicles

A connection routed to a main frame ground (refer to illustration Ground Stud to Frame Rail to Battery), can be used if the following guidelines are followed.

1. Connections to the frame must not be made with star washers. Star washers should not be counted on to remove paint from painted surfaces. Use flat washers for this connection, with the paint completely removed in this area.

2. Any paint must be completely removed from the frame rail at the point where the (-)Battery connection is made. Failure to do so reduces the effectiveness of the connection.

3. The ground path is not made through frame cross members. Bolted connections of frame cross members may not always provide required continuity for this critical connection.

4. Use conductive grease or other methods to reduce/eliminate the affect of corrosion on the frame rail connection.

Caterpillar does not recommend a connection from the engine ground stud to the main frame rail at a connection point different from where the (-)Battery connection is made. A two-point frame rail connection method depends on frame rail connections. Manufacturing process control of frame rail connections is difficult to control. This multiple frame rail connection scheme is also more difficult to troubleshoot.

Ground Stud Connection To ECM (-)Battery

Caterpillar is requiring the OEM install the ECM (-)Battery wire into their harness connector for 1994 and later. This connection should be #14 AWG wire from Connector P1 Pin-5 to the engine ground stud. Refer to Ground Stud to Starting Motor to Battery, and Ground Stud to Frame Rail to Battery.

* 3176B Ground Stud

The 3176B uses an M8x1.25 Thread stud with a 20 mm stud length located on the cylinder head. The stud has two washers and properly sized nut supplied for attaching all ground terminals supplied by the OEM.

Sensor Common

It is critical that only those components interfacing directly to the ECM be connected to Connector P1 Pin-29 via a dedicated return line. Connections to this pin include all OEM installed switches used for engine control purposes (switches, brake switches, Clutch Switch, engine retarder solenoid switches, A/C high pressure switch), the coolant level sensor, and the throttle position sensor. These components must not be connected to any vehicle ground. Note the list specifically excludes any relays or solenoids which may be driven by the ECM. These devices should not be grounded to Sensor Common.

* Switches Connected to Sensor Common

All switches connected to the control system must be an externally grounded, two wire design. Internally grounded (or case grounded) switches must not be used. Connecting switches or the throttle position sensor to the vehicle cab ground can degrade Control System performance.

Starting Motor, Alternator, Voltmeter and Ignition Switch(es)

Power Supply Connections to Start (Ignition) Switch(es)/Engine Starting Motor

1. Connect (+)Battery, using 14 AWG wire, to the (+) terminal of the Start (Ignition) Switch.

2. Connect the RUN terminal of the Start (Ignition) Switch, using 14 AWG wire, to Pin-6 of J1 Customer Connector.

3. Connect (-)Battery, using 14 AWG wire, to Pin-5 of J1 Customer Connector.

4. Connect (+)Battery, using 14 AWG wire with an in line 5A fuse, to Pin-4 of J1 Customer Connector.

NOTE: The ECM and CMS/EMS MUST be powered from the same ignition switch. The same battery source must be used for all (+)Battery and (-)Battery connections.

Vehicles may be equipped with an engine protection shutdown system (external to ECM) that interrupts electrical power to the ECM. These systems will not supply power to the ECM until the engine is cranked, until oil pressure achieves minimum acceptable limits or until an override button is pressed. These devices must not interrupt the Unswitched (+)Battery line. Current draw from the ECM through the Unswitched (+)Battery line is less than 10 mAmps (0.01 amps) and will not cause a battery to discharge unless the engine is unused for months.

5. Connect the START terminal of the Start (Ignition) Switch, using 14 AWG wire, to Starting Motor (Pinion Solenoid) Start terminal.

6. Connect (+)Battery post directly to the positive terminal on starting motor using the appropriate diameter (AWG) wire for the distance between connections.

7. Connect (-)Battery post directly to the negative terminal on starting motor using the appropriate diameter (AWG) wire for the distance between connections.