C4.4 Generator Set Engines Caterpillar

This procedure tests that the correct voltage is being supplied to the Electronic Control Module (ECM).

Use this procedure to troubleshoot the system when one of the following diagnostic codes is active or easily repeated:

• 0168-00 Electrical System Voltage high

• 0168-01 Electrical System Voltage low

• 0168-02 Electrical System Voltage erratic, intermittent, or incorrect

• 1834-02 Ignition Keyswitch loss of signal

The engine ECM receives electrical power (battery voltage) through the wiring from the Engine Interface Module (EIM). Unswitched battery+ voltage is supplied through P1: 7, 8, 15, 16 and 40. The battery- is supplied through P1: 1, 2, 3, 9 and 10. When the "RUN" push button is pressed, a relay in the EMCP3 control panel allows power to energize a relay in the EIM. This relay then supplies power to the Battery+ terminals on the ECM. When the engine ECM detects battery voltage at these inputs, the engine ECM will power up. When battery voltage is removed from this input, the engine ECM will power down.

The cause of an intermittent power supply to the engine ECM can occur on either the positive side or on the negative side of the battery circuit. The connections for the unswitched battery+ are routed through a 25 Amp fuse in the EIM.

Battery power to the diagnostic connector is available and the battery power to the data link connector is independent of the control panel. If power is required for the engine ECM without operating the engine, a wire must be installed between terminal 7 and terminal 3B in the box for the control panel.

For intermittent faults such as intermittent shutdowns that could be caused by the wiring on the genset, temporarily bypassing the wiring on the genset may be an effective means of determining the root cause. If the symptoms disappear with the bypass wiring, the wiring on the machine is the cause of the fault. A means of bypassing the wiring in the machine is explained in this test procedure.

Illustration 1	g01637188
Schematic for the battery supply circuit on engines with an EMCP3 control panel

Illustration 2	g01501393
Pin locations for the ignition keyswitch and battery supply circuit on the P1 connector (1) Battery- (2) Battery- (3) Battery- (7) Battery+ (8) Battery+ (9) Battery+ (10) Battery- (15) Battery- (16) Battery- (40) Ignition key switch

Test Step 1. Check for Active Diagnostic Codes or Logged Diagnostic Codes

1. Make sure that the emergency stop push button is reset to the normal position.

2. Connect the electronic service tool to the diagnostic connector.

3. Install a wire between terminal 7 and terminal 3B in the box for the control panel.

   Note: The installation of the wire will provide power to the engine ECM without starting the engine.

4. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes or logged diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

5. Remove the temporary wire between wire 7 and wire 3B in the box for the control panel.

Expected Result:

One of the following diagnostic codes is active or logged:

• 168-0 Electrical System Voltage high

• 168-1 Electrical System Voltage low

• 168-2 Electrical System Voltage erratic, intermittent, or incorrect

• 1834-2 Ignition Keyswitch loss of signal

Results:

• OK - Diagnostic codes 168-00, 168-01 or 168-2 or diagnostic code 1834-02 is active or logged. Proceed to Test Step 2.

• Not OK - No diagnostic code is active.

  Repair: The fault is no longer present. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

Test Step 2. Inspect Electrical Connectors And Wiring

1. Thoroughly inspect ECM engine harness connector P2, the connector on the control panel and the connections on the EIM. Refer to Troubleshooting, "Electrical Connectors - Inspect".

2. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector, the connector on the control panel and the EIM that are associated with the active diagnostic code.

   Refer to illustration 1.

3. Verify that the latch tab of the connector is correctly latched. Also verify that the latch tab of the connector has returned to the fully latching position.

4. Check the screw for the ECM connector for the correct torque of 5.0 N·m (44 lb in).

5. Check the harness for abrasions and for pinch points from the sensor to the ECM.

Expected Result:

All connectors, pins, and sockets should be completely coupled and/or inserted. The harness should be free of corrosion, abrasion, and pinch points.

Results:

• OK - Proceed to Test Step 3.

• Not OK - Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are completely coupled. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault. If the fault has not been eliminated, proceed to Test Step 3.

Test Step 3. Bypass the Machine Wiring

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Batteries give off flammable fumes which can explode. To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.

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NOTICE
Do not connect the bypass harness to the battery until all of the in-line fuses have been removed from the Battery+ line. If the fuses are not removed before connection to the battery, a spark may result.

Note: This bypass harness is only for test applications. This bypass harness must be removed before the machine is returned to service. The bypass harness can be used in order to determine if the cause of the intermittent problem is interruptions in battery power to the ECM.

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Illustration 3	g01637713
Schematic for the bypass application harness

2. Disconnect P1 from the ECM connector.

3. Connect a bypass harness to the ECM.

4. Remove the fuses from the Battery+ wires of the bypass harness and connect the Battery+ and the Battery- wires directly to the battery terminals.

5. Install the in-line fuses in the Battery+ wire of the bypass harness.

   Note: This bypass directly connects the circuit for the keyswitch to the ECM. The ECM will remain powered until the connection to the unswitched battery+ line is disconnected. Remove the fuses from the in-line fuse holders to power down the ECM. Do not connect the bypass to the battery terminals or do not remove the bypass from the battery terminals without first removing the in-line fuses.

6. Connect the electronic service tool to the diagnostic connector and verify that communication can be established.

   Note: Remove the bypass harness and restore all wiring to the original condition after testing.

Expected Result:

Installing the bypass eliminates the fault.

Note: The status of the "Ignition Keyswitch" will always indicate ON while the bypass harness is installed.

Results:

• OK - The symptoms disappear when the bypass harness is installed. Also, the symptoms return when the bypass harness is removed. Proceed to Test Step 4.

• Not OK -

  Repair: Perform the following procedure:

  1. Use a suitable multimeter to check the voltage at the battery terminals. If necessary, charge the battery and then check that the fault has been eliminated.

  2. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  3. Use the electronic service tool to check for active diagnostic codes.

  4. If a diagnostic code is still active, contact the technical communicator at a Caterpillar dealer.

     Note: This consultation can greatly reduce the repair time.

  5. If necessary, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  6. Use the electronic service tool in order to check that the fault is eliminated.

  7. If the fault is not eliminated, reinstall the original ECM.

  8. If the fault is eliminated with the test ECM, reconnect the suspect ECM. Verify that the active diagnostic code returns.

  9. If the active diagnostic code returns with the suspect ECM, replace the ECM.

  STOP

Test Step 4. Test the Engine Interface Module (EIM)

1. Disconnect wire 3A from terminal 8 on the EIM.

2. Use a suitable multimeter to measure the resistance between terminal 8 and terminal 7 on the EIM. The resistance should be approximately 73 Ohms.

3. Reconnect wire 3A to terminal 8 on the EIM.

4. Install a wire between terminal 7 and terminal 3B in the box for the control panel.

5. Use a suitable multimeter to measure the voltage between terminal 3A on connector 1 on the EIM and ground. The reading should be approximately 12 Volts DC.

6. Remove the temporary wire between terminal 7 and terminal 3B in the box for the control panel.

Expected Result:

The multimeter readings confirm that the EIM is operating correctly.

Results:

• OK - The multimeter readings confirm that the EIM is operating correctly. Proceed to Test Step 5.

• Not OK - The EIM is not operating correctly.

  Repair: Replace the EIM. Confirm that the fault has been eliminated.

  STOP

Test Step 5. Test the Wiring

1. Disconnect the connector from the control panel.

2. Disconnect connector 1 from the EIM.

3. Use a suitable multimeter to check for continuity between pin 48 on the connector for the control panel and pin 3A on connector 1 on the EIM. Reconnect the connector on the control panel.

4. Disconnect connector P1 from the engine ECM.

5. Use a suitable multimeter to check for continuity between the positive terminal on the battery and pin 5 on the EIM.

6. Use a suitable multimeter to check for continuity between pin P1:7 on the connector for the engine ECM and pin 53A on connector 1 on the EIM.

7. Use a suitable multimeter to check for continuity between pin P1:1 on the connector for the engine ECM and the negative terminal on the battery.

8. Use a suitable multimeter to check for continuity between pin 5 on connector 1 on the EIM and the negative terminal on the battery.

9. Use a suitable multimeter to check for continuity between P1:1 on the ECM and the negative terminal on the battery.

10. Reconnect connector 1 to the EIM.

11. Reconnect connector P1 to the engine ECM.

Expected Result:

All the tests show continuity in the wiring.

Results:

• OK - All tests provide continuity in the wiring. Repeat the procedure from Test Step 1.

• Not OK - One of the continuity tests indicates an open circuit in the wiring.

  Repair: Repair the wire with the open circuit or replace the wire with the open circuit.

  Confirm that the fault has been eliminated.

  STOP