3500B Direct Fuel Control Modification{1421, 7451} Caterpillar

Engine:

3516B (S/N: 1NW1)

3512B (S/N: 1PW1)

3516B (S/N: 2FW1)

3508B (S/N: 2HW1)

3508B (S/N: 3DW1)

3512B (S/N: 4AW1)

Introduction

The modification is recommended for the 3508B land and offshore petroleum engines, the 3512B land and offshore petroleum engines, and the 3516B land and offshore petroleum engines. These engines must be equipped with the electronic instrument panel that is used in applications when the external governor control produces an engine actuator signal of 0 to 200 mA. These applications include the SCR systems.

Description and Function

The engine ECM normally uses a desired speed signal to set the steady engine speed. This system depends on the engine ECM in order to govern the engine at a steady engine speed. Direct fueling bypasses the governor in the engine ECM. Also, direct fueling sends a signal directly to the injection portion of the engine ECM.

This modification consists of a control signal filter and a voltage converter. The voltage converter provides a control voltage (DCV) to the existing 9X-9591 Electrical Converter (Pulse Width Modulated). The electrical converter produces the PWM signal to the engine ECM. This modification allows systems that are SCR controlled to use an engine actuator signal of 0 to 200 mA in order to control a 3500B series engine. The modifications to the software within the engine ECM allow this control signal to directly control the virtual rack position of the engine. Input control current from the SCR control is proportional to desired fuel when the direct fuel control is exerted. The engine ECM still retains basic engine protection functions.

Illustration 1	g00616858

Once the modification is installed, the capabilities of load sharing that are built into the SCR control can be fully utilized. This makes it simple to repower a D399 engine with a 3500B series engine. This also makes it possible to parallel a 3500B series engine with a mechanical unit injected engines.

The following major components are added during this modification:

• One Control Group in order to convert the signal of 0 to 200 mA to an isolated DC voltage

• Software that is flashed into the engine ECM which allows the direct fueling to function

Glossary of Terms

Engine ECM - Electronic control module for 3500B series engines.

ECS (Engine Control Switch) - The switch is located on the electronic instrument panel or the engine ECM. The switch is considered to be the master control for the engine.

EIP (Electronic Instrument Panel) - The panel houses the electrical connections for the engine electrical, instrumentation and controls. The panel is usually mounted on the 3500B series engine but the panel may be mounted in a remote location.

Subpanel For The EIP - The subpanel is a steel plate that is mounted in the back interior of the EIP. This plate supports most of the internal components in the EIP.

Threaded Insert - The threaded insert is a nut fastener that compresses during installation. The fastener can be installed permanently from one side of a panel.

PWM (Pulse Width Modulation) - The use of PWM is a means of transmitting data by changing the ratio of "ON time" to "OFF time" in a square wave signal. A PWM signal is commonly used for throttle signals and sensor signals.

Electrical Converter - The electrical converter converts a DC voltage to a specific PWM duty cycle.

SCR (Silicon Controlled Rectifier) - A SCR is a solid state device that can be turned on at a specific point in the AC sine wave. These devices are the main switching elements in SCR systems that are used to control machinery that is used for petroleum drilling.

Voltage Converter - The converter is an electronic module that converts one voltage to another voltage. In general applications, the following conversions can be performed: VAC to VDC, VDC to VAC and one voltage type to the same voltage type. The conversion of voltage also offers the opportunity to isolate the input voltage from the output voltage. The converter that is installed in this special instruction uses this feature of isolation. This module is referred to in this special instruction as the green voltage converter.

Installation

Also, other basic hand tools are required. The following list is a list of common tools that are required: various screwdrivers, wrenches, crimper, electric drill, 1/4 inch drill bit and 3/8 inch drill bit

Rework Procedure

Hardware Installation

1. Ensure that the engine is off. Remove all power from the engine. Ensure that all sources of 24 DCV are disconnected from the engine. Open the door for the EIP.

2. Mark the location of the mounting hole for 174-1423 Converter Control and 174-1433 Inductor by using the illustration 6. Use a 1/4 inch drill bit in order to drill two holes into the subpanel for the EIP at the locations that are marked for the Converter Control .

3. Use the 178-7635 Threaded Insert Installation Tool in order to install the insert nut that is used to support the Converter Control. This is accomplished by threading the threaded insert all the way on the tool mandrel. Hold the tool with a box wrench. Turn the mandrel with another box wrench or a ratchet wrench until the fastener is installed.

4. Use the 3/8 inch drill bit and drill one hole at the location that is marked for the 174-1433 Inductor .

5. Use the 179-3571 Threaded Insert Installation Tool to install the 1/4 - 20 insert nut.

6. Locate the 174-1433 Inductor . Mount the inductor in the location that is shown on the illustration for the EIP subpanel. The inductor is mounted by using an 8B-2377 Bolt and a 4B-4863 Washer .

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Illustration 2	g00614590
174-1423 Converter Control (1) Inverted "U" In The Harness

7. Disconnect the three green connectors on the voltage converter. Carefully remove each of the connectors by grasping the conductor ferrule that is inserted into the connector. Pull the connector away from the converter.

8. Loosen the screws that are holding the end retainers in place. Remove the voltage converter from the Converter Control. Set the voltage converter to the side.

9. Mount the Converter Control with two (8-32) screws and washers.

10. Position the group of three resistors in the center of the inverted "U" in the harness. Slide the resistor holders left or right on the rail in order to locate the correct position. See illustration 6 for the location. Slide both of the end retainers against the resistor group and tighten the screws on the retainers.

11. Remove 10 mm of insulation from each of the leads for the inductor. Install a ferrule on each of the wire ends for the inductor if the leads do not have a ferrule. Connect one of the leads for the inductor to the terminal "R1B" on the Converter Control. Connect the remaining lead to the terminal "R2B" on the Converter Control.

12. Remove the screws that are supporting the 9X-9591 Electrical Converter (Pulse Width Modulated) in the upper right hand corner of the EIP subpanel. Lift the electrical converter away from the panel but do not disconnect any of the wires at this time.

13. Loosen the nut that is holding the ladder clip. The ladder clip is located above the 9X-9591 Electrical Converter (Pulse Width Modulated). Rotate the end of the ladder clip upward in order to allow access to the connectors on the voltage converter.

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Illustration 3	g00614913
(2) 4P-7581 Clip (3) 174-1428 Electrical Converter (Voltage) (4) Mounting latch for the Converter Control

14. Install the 174-1428 Electrical Converter (Voltage) under the 9X-9591 Electrical Converter (Pulse Width Modulated). The top of the converter will be on the left. The metal mounting latch will be on the lower side of the converter. See illustration 6. Use two 5S-9105 Screws and washers in order to retain the 9X-9591 Electrical Converter (Pulse Width Modulated). Turn the screws enough to retain the voltage converter. The screws will be fully tightened in a later step. Use a small screwdriver to check the torque of the screws on each of the small green connectors. Reinstall the three green connectors on the voltage converter. The connectors are keyed in order to prevent the connectors from being improperly connected.

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Illustration 4	g00614939

15. Position the converter according to the illustration. Apply thread lock to the threads of the screws that are retaining the electrical converter. Tighten the screws in order to secure both converters.

16. Connect the leads for 24 DCV of the voltage converter to the terminals for 24 DCV on the electrical converter.

17. Disconnect any existing leads on pin 1, pin 2 and pin 3 of the electrical converter. Connect the three leads "PWM-1", "PWM-2" and "PWM-3" to the respective pins on the electrical converter.

18. Locate the customer connector "C" on the bottom of the EIP. Route the 174-1434 Wiring Harness to the connector. Position the connector pins at the customer connector and the ferrule ends at the newly installed Converter Control .

19. Insert the connector pins into the interior side of the connector until the pins lock in place. The conductor "F890C" goes to pin 1 and the conductor "G807B" goes to pin 2.

    Note: There is a possibility that the small white dust plugs must be removed before the pins are inserted.

20. Route the other end of the harness to the resistor assembly on the Converter Control. Insert the ferrule on the conductor "F890C" into the terminal block "R1A". Tighten the retaining screw on the terminal. Insert the ferrule on the conductor "G807B" into the terminal block "R2A". Tighten the retaining screw on the terminal. "F890C" is the positive current lead and "G807B" is the negative current signal. The 0 to 200 mA signal that is provided is connected to these two pins.

    Note: If this harness is not used, the 0 to 200 mA signal can be routed directly to the terminal blocks "R1A" and "R2A" on the Converter Control. The positive lead of the control signal is connected to "R1A". The negative lead of the control signal is connected to "R2A". DO NOT MAKE FINAL CONNECTIONS OF THE 0 TO 200 MILLIAMPERE SIGNAL AT THIS TIME. FINAL CONNECTIONS WILL BE MADE IN ""OPERATIONAL CHECK" ".

21. Locate pins 1 and 2 on the low idle switch. The switch is mounted inside the EIP. Remove the terminal lug on pin 1 of the switch F707-GN. Connect the terminal to pin 2 of the switch. This action shorts out the low idle switch. Remove the label "Low Idle Switch" that is located next to the switch.

    Note: The low idle switch should remain installed in the EIP. The switch is required if the engine is returned to the desired speed operation instead of direct fueling.

Software Installation

Use the WinFlash utility within the Caterpillar Electronic Technician (ET). Flash software file "176-6176.fls" into the engine ECM. The "Direct Fueling Configuration Parameter" must be changed to "ON" in order to activate the direct fuel feature. A factory password must be generated in order to proceed. This is accomplished by contacting a Caterpillar dealer. Once the password is received, enter the password and change the parameter to "ON".

Note: This software part number is compatible with 3512B engines only. For 3508B engines, use "178-9617.fls" for flashing. For 3516B engines, use "178-9164.fls". Check with 3500 Customer Service in order to verify the most recent version of this software.

Operational Check

1. Be sure to follow this procedure when you are connecting all the wires.

2. Ensure that the Emergency Stop Button is in the reset position.

3. Ensure that the Engine Control Switch is in the OFF position.

4. Connect the 0 to 200 mA signal to pin 1 and pin 2 of the customer connector or connect the signal to "R1A" and "R2A" of the Converter Control .

   Note: The external engine control system is now in control of the engine speed. Any increase in the current flow in the signal line will increase the engine speed. Ensure that the external engine control is adjusted in order to provide a proper engine speed when the engine is started.

5. Apply 24 DCV to the engine.

6. Start the engine and observe the engine speed.

7. Stop the engine by turning the Engine Control Switch to "OFF".

8. Start the engine and observe the engine speed. The external engine control system will increase engine speed by increasing the control current.

9. Operate the engine at various loads. Some adjustments to the external control system may be necessary to optimize the response.

10. Stop the engine by turning the Engine Control Switch to OFF.

Final Assembly

1. Secure any loose wires in the EIP with tie straps.

2. Ensure that all fasteners are tightened to proper torque levels.

3. Close and secure the door to the EIP.

Maintenance

Theory of Operation

Inductor "L1" and resistors ("R1" and "R2") replace the standard load for the actuator. The control signal for the analog speed was originally designed to drive this load. The 0 to 200 mA speed controller must be connected to this impedance. If the speed controller is not connected then the controller may not work correctly for the following reasons:

• Some controllers operate by using a switched voltage that requires the 50 mH inductance from the rack actuator.

• Some controllers operate by supplying a voltage that requires the rack actuator's 30-50 Ohm resistance to regulate the current.

Resistor "R2" converts the 0 to 200 mA signal into a voltage for the voltage converter. This converter provides isolation between the analog speed control and the engine ECM. The 9X-9591 Electrical Converter (Pulse Width Modulated) converts the analog voltage signal from the voltage converter into a PWM signal for the engine ECM. This signal sets the engine fuel rack. The expected conversion of the fuel control hardware is shown in Table 4. Resistor "R3" provides a bias voltage that is used as the negative reference for the output for the voltage converter. This bias voltage sets the minimum duty cycle of the electrical converter to 5%. The engine ECM uses the signal from the electrical converter to control the duration of injection.

Troubleshooting

Table 4 shows the expected values for the voltage and the PWM duty cycle. Most difficulties can be resolved by comparing Table 4 to the measurements that were taken for the voltages and the duty cycles. If the duty cycle is out of the 5% to 95% range, the engine ECM will generate a diagnostic code of CID 091 FMI 08.

Illustration 5	g00616513
Schematic of the Converter

Illustration 6	g00616557
Location of the Mounting Holes (1) Upper Right Hand Corner Of The EIP Subpanel (2) New Holes For Converter Control (3) New Hole For Inductor