3512C and 3516C Engines Caterpillar

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

The ECM has the ability to automatically prelube the engine before cranking. This prelubrication may increase the life of certain engine parts. The ECM will prelube the engine, when the Engine Control Switch (ECS) is placed in the START position. The ECM will prelube the engine, when the ECS is placed in the AUTO position and the remote start/run/stop switch is closed. The length of time for the prelube cycle can be programmed by the customer. The prelube cycle will end when the pressure switch for the prelube system closes or if the customer programmed time ends. The engine speed must equal zero rpm before the prelube will begin.

The prelube cycle has the following status codes.

"OFF" - The ECM is powered and the ECS is in the STOP position.

"ON" - The ECM is powered and the ECS is in the START position.

"COMPLETED" - The prelube has timed out or the prelubrication pressure switch has activated.

"DISABLED" - The engine prelube duration is programmed to 0.

The prelube function will be aborted when one of the following conditions occur:

• The pressure switch for the prelube system is activated.

• The user defined engine prelube duration has been reached.

• The operator activates the prelube override switch.

When the ECM senses the ECS in the START position, the ECM will activate the output driver for the "PPR1" relay. When the "PPR1" relay energizes, the normally open contacts of the "PPR1" relay close. This allows current to flow to the prelube motor. The prelube motor activates the prelube pump. The prelube pump builds pressure in the engine's lubrication system. When the pressure switch for the prelube system closes as a result of the increased pressure, the ECM input for the pressure switch is taken low. The ECM then knows that the pressure in the system is adequate. The ECM will begin the starting sequence.

A test on Caterpillar Electronic Technician (ET) allows the technician to activate the prelube system. The test is functional when the engine speed is 0 rpm. The test is accessed by selecting the following menus on Cat ET:

• "Diagnostics"

• "Diagnostic Tests"

• "Override Parameters"

Illustration 1	g01241988
Typical schematic

Illustration 2	g01241989
P1 ECM connector (P1-5) Digital return (P1-66) Prelube override switch

Illustration 3	g01241990
P2 ECM connector (P2-12) Driver output for Prelube (P2-66) Digital return

Illustration 4	g01241992
Customer connector (Terminal i) Prelube override switch (Terminal y) PPR2 contacts (Terminal z) PPR2 contacts

Illustration 5	g01234146
Location of ECM connectors

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the ECS to the OFF position.

2. Thoroughly inspect the ECM connectors. Inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

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 ECM connector (allen head screw) 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 are 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. Restore power to the ECM.

3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

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

5. Activate the prelube override.

6. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

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 06 diagnostic code is active at this time. Proceed to Test Step 3.

• Not OK - A 05 diagnostic code is active at this time. Proceed to Test Step 4.

Test Step 3. Create an Open Circuit at the PPR1 Relay and at the PPR2 Relay

1. Remove power from the ECM.

2. Disconnect wire F705-BK(Black) from terminal 3 of PPR1 and from terminal 86 of PPR2.

3. Restore power to the ECM.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

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

6. Activate the prelube override.

7. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

8. Remove power from the ECM.

Expected Result:

A 05 diagnostic code is now active for the prelube relay.

Results:

• OK - A 05 diagnostic code is now active for the PPR1 relay. The wires between the ECM and the PPR1 relay are OK.

  Repair: Replace the PPR1 relay. Reconnect all wires to the original configuration. Recheck the prelube system with the prelube override. If a 05 diagnostic code is active, replace the PPR2 relay. Recheck the prelube system with the prelube override. If a 05 diagnostic code is no longer active, reinstall the old PPR1 relay. Clear any logged diagnostic codes.

  STOP

• Not OK - A 06 diagnostic code remains active. There is a short between the PPR1 relay and the ECM. Leave the wires for the PPR1 relay disconnected. Proceed to Test Step 5.

Test Step 4. Create a Short Circuit at the PPR1 Relay and at the PPR2 Relay

1. Remove power from the ECM.

2. Disconnect wire F705-BK(Black) from terminal 3 of PPR1 and from terminal 86 of PPR2. Install a jumper wire between wire F705-BK(Black) and engine ground.

3. Restore power to the ECM.

   Note: Monitor the "Active Diagnostic Codes" screen on Cat ET after installing the jumper wire.

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

5. Activate the prelube override.

   Note: Monitor the "Active Diagnostic Codes" screen on Cat ET.

6. Wait at least 15 seconds for activation of the 06 diagnostic code.

7. Remove power from the ECM. Remove the wire jumper.

Expected Result:

A 06 diagnostic code is active when the jumper wire is installed. A 05 diagnostic code is active when the jumper wire is removed.

Results:

• OK - The engine harness and the ECM are OK.

  Repair: Temporarily connect a new PPR1 relay. Verify that there are no active diagnostic codes for the prelube relay. Clear any logged diagnostic codes.

  STOP

• Not OK - The 05 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. Check the Operation of the ECM

1. Check the operation of the ECM by creating an open at the ECM.

   1. Disconnect the J2/P2 ECM connector.

   2. Remove wire F705-BK(Black) from P2-12.

   3. Install a wire jumper into the socket for P2-12.

   4. Reconnect the ECM connector.

   5. Restore power to the ECM.

      Note: Monitor the "Active Diagnostic Codes" screen on Cat ET.

   6. Wait at least 15 seconds for activation of the 05 diagnostic code.

2. Check the operation of the ECM by creating a short at the ECM.

   1. Install a wire jumper between the wire jumper in P2-12 and engine ground.

   2. Restore power to the ECM.

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

   4. Activate the prelube override.

      Note: Monitor the "Active Diagnostic Codes" screen on Cat ET.

   5. Wait at least 15 seconds for activation of the 06 diagnostic code.

3. Remove power from the ECM. Reconnect all wires to the original configuration.

Expected Result:

A 05 diagnostic code is active when the wire from the prelube relay is removed from the ECM connector. A 06 diagnostic code is active when the wire jumper in P2-12 is connected to engine ground.

Results:

• OK - The ECM is operating properly. The problem is in the wiring between the ECM and the connector for 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 05 diagnostic code is not active when the wire for the prelube relay is disconnected. The 06 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 Output Voltage to the Prelube Motor from the "PPR1" Relay

1. Turn the ECS to the OFF/RESET position.

2. Remove wire G705-BK(Black) from terminal 2 of the "PPR1" relay.

3. Connect one end of the voltmeter to the −Battery terminal.

4. Connect the other lead of the voltmeter to terminal 2 of the "PPR1" relay.

5. Turn the ECS to the STOP position.

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

7. Activate the prelube override.

8. Monitor the voltage on the voltmeter.

9. Disable the prelube override.

10. Remove power from the ECM. Reconnect 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 7.

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

  Repair: Verify that voltage is present on terminal 1 of the PPR1 relay. If voltage is present on terminal 1 of the PPR1 relay, verify that the breaker for the prelube is not tripped. If voltage is present at the breaker for the prelube, repair the wire K708-BK(Black) between the PPR1 relay and the breaker for the prelube.

  STOP

Test Step 7. Check the Voltage at the Prelube Motor

1. Turn the ECS to the OFF/RESET position.

2. Remove wire G705-BK(Black) from the prelube motor.

3. Connect one end of the voltmeter to wire G705 at the prelube motor.

4. Connect the other end of the voltmeter to the −Battery terminal.

5. Turn the ECS to the STOP position.

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

7. Activate the prelube override.

8. Monitor the voltage on the voltmeter.

9. Disable the prelube override.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. There is a problem in the prelube motor. Proceed to Test Step 8.

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

  Repair: There is a problem with the wire G705 between the prelube motor and terminal 2 of the PPR1 relay. Repair wire G705.

  STOP

Test Step 8. Check the Operation of the Prelube Motor.

1. Turn the ECS to the OFF/RESET 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 +Battery terminal of the prelube motor.

Expected Result:

The prelube motor starts.

Results:

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

  Repair: Inspect the connectors at the prelube motor.

  STOP

• Not OK - The prelube motor did not start.

  Repair: Verify that wire H705 has continuity between the prelube motor and the breaker for the prelube. If wire H705 is OK, replace the prelube motor with a new prelube motor. Verify that the problem is no longer present.

  STOP