3508B Engine for 854G Wheel Dozers and 992G Wheel Loaders Caterpillar

Use this test only when there are active or there are logged occurrences of CID-FMI: 168-00, 168-01 and 168-02. Use this test if there are intermittent engine shutdowns or if a difficulty in starting is not accompanied by loss of electrical accessories. Engine shutdowns that are accompanied by a loss of other electrical accessories indicate a problem in the keyswitch or in the load reduction relay circuit. This does not indicate a problem in the wiring at the engine's Electronic Control Module (ECM). Verify that there are no problems with the starting system or the charging system before you use this test.

There are two + Battery and there are two - Battery lines to the ECM in order to reduce resistance at the harness. The ECM continuously receives battery voltage through a 15 Amp Breaker. When the ECM senses the battery voltage at the keyswitch, the ECM turns ON. When the voltage is removed from the keyswitch, the ECM turns OFF. The current draw from the batteries is approximately 3 Amp when the keyswitch is in the ON position and the engine is running. The current draw from the batteries is zero when the keyswitch is in the OFF position.

Illustration 1	g00909055
Typical example

Test Step 1. Check for Connector Damage

1. Turn the circuit breaker for the engine to the OFF position.

2. Turn the keyswitch to the OFF position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

4. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

5. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the wiring for abrasion and for pinch points.

Expected Result:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - The connectors and wiring are okay. Proceed to test step 2.

• Not OK - The connectors and/or wiring need repair.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 2. Check the Voltage at the Battery Post.

1. Turn the circuit breaker for the engine to the ON position.

2. Turn the keyswitch to the ON position. The engine should be off.

3. Measure the voltage at the battery posts.

Expected Result:

The voltage should be 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to test step 3.

• Not OK - The voltage is not 24 ± 3 VDC.

  Repair: There is a problem with the batteries or the charging system. Refer to Testing and Adjusting, "Charging System".

  Stop.

Test Step 3. Check the Voltage to the ECM.

1. Turn the keyswitch to the OFF position. The engine should be off.

2. Turn the circuit breaker for the engine to the OFF position.

3. Remove ECM connector J1/P1.

4. Turn the circuit breaker for the engine to the ON position.

5. Turn the keyswitch to the ON position. The engine should be off.

6. Measure the voltage between P1-4 and P1-11 at the ECM connector P1.

7. Measure the voltage between P1-6 and P1-5 at the ECM connector P1.

Expected Result:

The voltage should be ± 1 VDC from the voltage at the battery terminals.

Results:

• OK - The voltage should be ± 1 VDC from the voltage at the battery terminals. The voltage at the ECM is okay. Proceed to test step 4.

• Not OK - The voltage should be ± 1 VDC from the voltage at the battery terminals. The voltage is not correct at the ECM.

  Repair: There is an open circuit or excessive resistance in the wiring or connections between the batteries and the ECM. Verify that the breaker for the Engine Control is not tripped. Verify that the connection for the engine ground is clean and tight. Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 4. Check the Voltage at the Input for the Keyswitch at the ECM.

1. Measure the voltage between wire 113-OR from ECM connector P1-23 and wire 229-BK from ECM connector P1-11.

2. Turn the keyswitch to the OFF position. The engine should be off.

3. Turn the circuit breaker for the engine to the OFF position.

4. Reconnect all wires and connectors.

Expected Result:

The voltage should be 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to test step 7.

• Not OK - The voltage is not 24 ± 3 VDC. Proceed to test step 5.

Test Step 5. Check the Voltage at the Keyswitch.

1. Turn the circuit breaker for the engine to the ON position.

2. Turn the keyswitch to the ON position. The engine should be off.

3. Measure the voltage between terminal R and engine ground at the keyswitch.

4. Turn the keyswitch to the OFF position. The engine should be off.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to test step 6.

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: Check for 24 ± 3 VDC at terminal B of the keyswitch. If voltage is present on terminal B of the keyswitch, replace the keyswitch. If voltage is not present on terminal B of the keyswitch, verify that the breaker for the keyswitch is not tripped. Repair the wiring and/or terminals between the keyswitch, the key circuit breaker and the Battery.

  Stop.

Test Step 6. Check the Voltage at the Main Power Relay.

1. Turn the keyswitch to the ON position. The engine should be off.

2. Measure the voltage between the fuse for the "VIMS/Payload Monitor" and the engine ground.

3. Turn the keyswitch to the OFF position. The engine should be off.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Verify that the fuse for the Monitor is not tripped. Repair the wiring and/or connectors between the fuse for the Monitor and the input for the keyswitch at the ECM.

  Stop.

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: Verify that 24 ± 3 VDC is present at the Main power relay on wire 106-RD and on wire 308-YL. If voltage is not present on wire 308-YL, repair the wire 308-YL. If voltage is not present on wire 106-RD, verify that the Main breaker and/or the Alternator circuit breaker are not tripped. Check the wire 200-BR for continuity to ground from the Main Power Relay. If the wire to ground is okay and 24 ± 3 VDC is present on the wires 106-RD and 308-YL at the Main power relay, replace the Main Power Relay.

  Stop.

Test Step 7. Check for "ACTIVE" Diagnostic Codes.

1. Turn the circuit breaker for the engine to the ON position.

2. Turn the keyswitch to the ON position. The engine should be off.

3. Connect the Caterpillar Electronic Technician (ET) to the cab service tool connector J42. Start the Cat ET.

4. Check for active diagnostic codes 262-03 and/or 262-04.

5. Check for active diagnostic codes 263-03 and/or 263-04.

Expected Result:

The diagnostic codes 262-03 and/or 262-04 should not be active. The diagnostic codes 263-03 and/or 263-04 should not be active.

Results:

• OK - The diagnostic codes 262-03 and/or 262-04 are not active. The diagnostic codes 263-03 and/or 263-04 are not active. Proceed to test step 8.

• Not OK - The diagnostic codes 262-03 and/or 262-04 are active.

  Repair: Perform the diagnostic functional test Troubleshooting, "Analog Sensor Supply".

  Stop.

• Not OK - The diagnostic codes 263-03 and/or 263-04 are active.

  Repair: Perform the diagnostic functional test Troubleshooting, "Digital Sensor Supply".

  Stop.

Test Step 8. Check the Analog Sensor Power Supply.

1. Turn the keyswitch to the OFF position. The engine should be off.

2. Turn the circuit breaker for the engine to the OFF position.

3. Remove the analog supply wire 997-OR from ECM connector P1-36. Install a wire jumper into the socket for P1-36.

4. Remove the analog return wire 993-BR from ECM connector P1-30. Install a wire jumper into the socket for P1-30.

   Note: Disconnecting the common sensor wire from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor common. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

5. Turn the circuit breaker for the engine to the ON position.

6. Turn the keyswitch to the ON position. The engine should be off.

7. Measure the voltage between the wire jumpers in P1-36 and in P1-30.

8. Turn the keyswitch to the OFF position. The engine should be off.

9. Turn the circuit breaker for the engine to the OFF position.

10. Remove the jumper wires and reconnect all wires.

Expected Result:

The voltage should be 5 ± 0.2 VDC.

Results:

• OK - The voltage is 5 ± 0.2 VDC. Proceed to test step 9.

• Not OK - The voltage is not 5 ± 0.2 VDC.

  Repair: Replace the ECM with a new ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.

Test Step 9. Check the Digital Sensor Supply.

1. Remove the digital supply wire A700-OR from ECM connector P1-35. Install a wire jumper into the socket for P1-35.

2. Remove the digital return wire 998-BR from ECM connector P1-29. Install a wire jumper into the socket for P1-29.

   Note: Disconnecting the common sensor wire from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor common. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

3. Turn the circuit breaker for the engine to the ON position.

4. Turn the keyswitch to the ON position. The engine should be off.

5. Measure the voltage between P1-35 and P1-29.

6. Turn the keyswitch to the OFF position. The engine should be off.

7. Turn the circuit breaker for the engine to the OFF position.

8. Remove the jumper wires and reconnect all wires.

Expected Result:

The voltage should be 8 ± 0.4 VDC.

Results:

• OK - The voltage is 8 ± 0.4 VDC.

  Repair: The Electrical Power Supplies are operating correctly. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

• Not OK - The voltage is not 8 ± 0.4 VDC.

  Repair: Replace the ECM with a new ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.