3500B and 3500C Locomotive Engines Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with a prelubrication system or if one of the diagnostic codes in Table 1 is active or easily repeated.

The ECM has the ability to automatically lubricate the engine before cranking. This may increase the life of certain engine parts by lubricating the parts before the starting motor is engaged.

The prelubrication system is activated when the start/run/stop switch is turned to the START position. The ECM prevents the starting motor from engaging while the pump builds pressure in the engine oil system. After a short period of time, the starting motor is allowed to engage. The start/run/stop switch must be left in the START position for the duration of the prelube cycle in order to ensure that the engine is properly lubricated before start-up.

A test on Caterpillar Electronic Technician (ET) allows the technician to activate the prelube system. The test is functional only when the engine speed is zero rpm. The test is accessed by selecting the following menus on Cat ET:

• "Diagnostics"

• "Diagnostic Tests"

• "Override Parameters"

Illustration 1	g01259105
Typical schematic

Illustration 2	g01213742
P1 ECM connector (P1-5) Digital return (P1-66) Pressure switch for the prelube system

Illustration 3	g01213744
P2 ECM connector (P2-12) Prelube relay (P2-22) Return for the prelube relay

Illustration 4	g01259107
Connector "A" (Terminal 25) Digital return

Illustration 5	g01234146
Location of ECM connectors

Illustration 6	g01259113
Connector "B" (Terminal 35) Return for the prelube relay (Terminal 36) Drive for the prelube relay (Terminal 37) Pressure switch for the prelube system

Test Step 1. INSPECT THE ELECTRICAL CONNECTORS AND THE WIRING

1. Turn the breaker for the ECM to the OFF position.

2. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the proper procedure for inspecting system wiring.

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

4. Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

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

Expected Result:

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

Results:

• OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.

• Not OK - There is a problem in the connectors and/or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.

  Verify that the repair eliminates the problem.

  STOP

Test Step 2. CHECK FOR ACTIVE DIAGNOSTIC CODES

1. Connect Cat ET to the service tool connector.

2. Turn the breaker for the ECM to the ON position.

3. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

4. Select diagnostic tests from Cat ET.

5. Select the "Override Parameters" screen on Cat ET.

6. Activate the prelube override.

7. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

8. Disable the prelube override.

Expected Result:

No diagnostic codes are active.

Results:

• OK - No diagnostic codes are active, but a problem is suspected in the prelube system. Proceed to Test Step 6.

• Not OK - A -6 diagnostic code is active at this time. Proceed to Test Step 3.

• Not OK - A -5 diagnostic code is active at this time. Proceed to Test Step 4.

Test Step 3. CREATE AN OPEN AT THE PRELUBE RELAY

1. Turn the breaker for the ECM to the OFF position.

2. Disconnect wire F705-PK(Pink) from terminal 86 of the prelube relay.

3. Turn the breaker for the ECM to the ON position.

4. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

5. Select diagnostic tests from Cat ET.

6. Select the "Override Parameters" screen on Cat ET.

7. Activate the prelube override.

8. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

9. Turn the breaker for the ECM to the OFF position.

Expected Result:

A -6 diagnostic code was active for the prelube relay. After creating an open at the prelube relay, a -5 diagnostic code is now active for the prelube relay.

Results:

• OK - A -6 diagnostic code was active before disconnecting the wire. A -5 diagnostic code became active after disconnecting the wire. The harness and the ECM are OK. The problem may be in the prelube relay.

  Repair: Verify that wire A268-BK(Black) is not shorted to another wire in the harness. Check wire A268-BK(Black) for continuity to the ECM. If wire A268-BK(Black) is OK, install a new prelube relay. Verify that there are no active diagnostic codes for the prelube relay. Clear any logged diagnostic codes.

  STOP

• Not OK - A -6 diagnostic code remains active. The short is between the prelube relay and the ECM. Leave the wire F705-PK(Pink) disconnected. Proceed to Test Step 5.

Test Step 4. CREATE A SHORT AT THE CONNECTOR FOR THE PRELUBE RELAY

1. Turn the breaker for the ECM to the OFF position.

2. Install a jumper wire between terminal 85 and terminal 86 of the prelube relay.

3. Turn the breaker for the ECM to the ON position.

4. Select diagnostic tests from Cat ET.

5. Select the "Override Parameters" screen on Cat ET.

6. Activate the prelube override.

7. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

8. Select diagnostic tests from Cat ET.

9. Select the "Override Parameters" screen on Cat ET.

10. Activate the prelube override.

11. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

12. Disable the prelube override.

13. Turn the breaker for the ECM to the OFF position. Remove the wire jumper.

Expected Result:

A -6 diagnostic code is active when the jumper wire is installed. A -5 diagnostic code is active when the jumper wire is removed.

Results:

• OK - A -6 diagnostic code is active when the jumper wire is installed. A -5 diagnostic code is active when the jumper wire is removed. The engine harness and the ECM are OK. The open circuit is in the coil of the prelube relay.

  Repair: Install the new prelube relay. Clear any logged diagnostic codes.

  STOP

• Not OK - The -5 diagnostic code remains active with the jumper in place. The open circuit is between the ECM and the connector for the prelube relay. Proceed to Test Step 5.

Test Step 5. TEST THE OPERATION OF THE ECM

1. Turn the breaker for the ECM to the OFF position.

2. Fabricate two jumper wires that are long enough to create a test circuit at the ECM connector. Crimp a connector socket to one end of each of the jumper wires.

3. Disconnect the J2/P2 ECM connector.

4. Remove the wire for the prelube relay from the P2 ECM connector.

5. Install the jumper wire into the terminal location for the prelube relay at the ECM connector.

6. Connect the ECM connector.

7. Check the operation of the ECM by creating an open at the ECM connector:

   1. Hold the loose end of the jumper wire away from any components in order to create an open circuit condition.

   2. Turn the breaker for the ECM to the ON position.

   3. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active -5 diagnostic code.

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

   4. Select diagnostic tests from Cat ET.

   5. Select the "Override Parameters" screen on Cat ET.

   6. Activate the prelube override.

   7. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

   8. Disable the prelube override.

8. Check the operation of the ECM by creating a short circuit at the ECM connector:

   1. Short the jumper wire in the socket for the prelube relay to engine ground.

   2. Turn the breaker for the ECM to the ON position.

   3. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

   4. Select diagnostic tests from Cat ET.

   5. Select the "Override Parameters" screen on Cat ET.

   6. Activate the prelube override.

   7. Monitor the active diagnostic code screen on Cat ET. Check the prelube system for an active diagnostic code.

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

   8. Disable the prelube override.

9. Turn the breaker for the ECM to the OFF position. Restore the wiring to the original configuration.

Expected Result:

A -5 diagnostic code is active when the wires from the prelube relay are open at the ECM connector. A -6 diagnostic code is active if the wires from the prelube relay are shorted at the ECM connector.

Results:

• OK - The ECM is operating properly. The problem is in the wiring between the ECM and the prelube relay.

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

  STOP

• Not OK - One of the following conditions exists: The -5 diagnostic code is not active when the wire for the prelube relay is disconnected. The -6 diagnostic code is not active when the wire jumper is installed.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP

Test Step 6. CHECK THE VOLTAGE TO THE COIL OF THE PRELUBE SWITCH

1. Disconnect wire 150-OR(Orange) from terminal 4 on the prelube switch.

2. Connect a voltmeter between wire 150-OR(Orange) and engine ground.

3. Turn the breaker for the ECM to the ON position.

4. Proceed to the "Diagnostic Overrides" screen on Cat ET.

5. Activate the prelube override.

6. Measure the voltage between wire 150-OR(Orange) and engine ground.

7. Turn the breaker for the ECM to the OFF position.

8. Replace all wires to the original configuration.

Expected Result:

The voltage measures 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.

  Repair: Perform the following steps.

  1. Remove wire 150-OR(Orange) from terminal 30 on the prelube relay. Activate the prelube override and measure the voltage between terminal 30 on the prelube relay and engine ground. If voltage is present on terminal 30 on the prelube relay, repair the wire 150-OR(Orange).

     If 24 ± 3 VDC is not present on terminal 30 on the prelube relay, measure the voltage to terminal 87 on the prelube relay. If 24 ± 3 VDC is not present on terminal 87 of the prelube relay, verify that the wiring between the battery and the prelube relay is OK.

  2. If 24 ± 3 VDC is present on terminal 87 on the prelube relay, replace the prelube relay and retest the prelube system.

  STOP

Test Step 7. CHECK THE VOLTAGE AT THE PRELUBE MOTOR

1. Disconnect the wire to the prelube motor from the prelube switch.

2. Connect a voltmeter between the wire and engine ground.

3. Turn the breaker for the ECM to the ON position.

4. Proceed to the "Diagnostic Overrides" screen on Cat ET.

5. Activate the prelube override.

6. Measure the voltage between the wire and engine ground.

7. Turn the breaker for the ECM to the OFF position.

8. Replace all wires to the original configuration.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 8.

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

  Repair: Perform the following steps.

  1. Remove the wire from terminal 2 of the prelube switch. Activate the prelube override and measure the voltage between terminal 2 and engine ground. If voltage is present on terminal 2, repair the wire between terminal 2 and the prelube motor.

  2. If voltage is not present on terminal 2, verify that the wire 229-BK(Black) has continuity to engine ground. If wire 229-BK(Black) has continuity to engine ground, measure the voltage on terminal 1 of the prelube switch. If 24 ± 3 VDC is present on terminal 1 of the prelube switch and the wire 229-BK(Black) is not open, replace the prelube switch and retest the prelube system.

  3. If 24 ± 3 VDC is not present on terminal 1 of the prelube switch, repair the wiring between the battery and the prelube switch.

  STOP

Test Step 8. CHECK THE OPERATION OF THE PRELUBE MOTOR

1. Turn the breaker for the ECM to the OFF position.

2. Connect one side of a suitable piece of 10 AWG wire to the +Battery terminal.

3. For one second, connect the other end of the wire to the positive terminal of the prelube motor.

Expected Result:

The prelube motor starts while the wire is connected to the positive terminal of the prelube motor.

Results:

• OK - The prelube motor starts. There is a problem in the wiring harness at the prelube motor.

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

  STOP

• Not OK - The prelube motor did not start.

  Repair: Verify that the wire to ground at the prelube motor has continuity to engine ground. If the wire to ground is OK, the problem is in the prelube motor. Install a new prelube motor. Verify that the problem is no longer present.

  STOP