3126B and 3126E On-highway Engines Caterpillar

Use this procedure under the following situation:

Use this procedure to determine if the circuit for the change oil lamp is operating properly. There are no diagnostic codes for this circuit.

Output 1 can operate as a change oil lamp or as a PTO switch on lamp. The parameter "Change Oil Lamp" must be programmed to "J1/P1:30" in order to use "Output 1" as a change oil lamp. The change oil lamp illuminates when the engine oil change interval has been exceeded.

The following parameters determine when the Engine Control Module (ECM) will illuminate the change oil lamp.

• "Maintenance indicator mode"

• "PM1 interval"

• "PM1 engine oil capacity"

If "Maintenance Indicator Mode" is programmed to "Manual - Distance" or "Manual - Hours", the parameter "PM1 Interval" must be programmed. If "Maintenance Indicator Mode" is programmed to "Automatic - Distance" or "Automaitc - Hours", the parameter "PM1 Engine Oil Capacity" must be programmed.

Electrical Connections of the Lamp

One terminal of the lamp must be connected to battery voltage through the vehicle wiring. The other terminal is connected to the ECM at the vehicle harness connector J1/P1-30.

The ECM provides a path to ground that will turn on the lamp.

The following components can cause problems with the circuit for the change oil lamp:

• Wiring or an electrical connector

• Lamp

• ECM

The most likely cause of a problem is the wiring or a connector. The least likely cause is a problem with the ECM.

Illustration 1	g01152388
Circuit schematic for the change oil lamp

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

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Illustration 2	g01146374
Left side engine view (typical example) (1) J1/P1 ECM connectors

2. Thoroughly inspect ECM vehicle harness connector J1/P1, the firewall bulkhead connector, and the terminals for the change oil lamp.

   Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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Illustration 3	g01152390
P1 connector (P1-30) Change oil lamp (P1-52) Unswitched +Battery (P1-65) -Battery

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

4. Check the allen head screw for the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.

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

Expected Result:

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

Results:

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

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

  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 Normal Operation of the Change Oil Lamp

1. Turn the keyswitch to the ON position. Monitor the change oil lamp. The ECM will illuminate the lamp for 5 seconds.

2. Turn the keyswitch to the OFF position.

Expected Result:

The change oil lamp illuminates for five seconds after the keyswitch is turned to the ON position.

Results:

• OK - The change oil lamp is operating normally.

  Repair: There may be an intermittent problem with the wiring and/or the connectors. Repair the lamp circuit or send the vehicle to the OEM dealer for repairs.

  Stop.

• Not OK - The lamp does not turn on. Proceed to Test Step 3.

Test Step 3. Test the Change Oil Lamp Circuit

1. Fabricate a jumper wire that can be used to test the circuit. Crimp connector pins to each end of the jumper.

2. Disconnect the J1/P1 ECM connectors.

3. Insert the jumper into terminal P1-30 (change oil lamp).

4. Insert the other end of the jumper wire into terminal P1-52 (-Battery).

5. While the lamp is being watched, insert the jumper wire and remove the jumper wire from terminal P1-65.

6. Remove the jumper wire from the ECM connector.

Expected Result:

Result 1 The change oil lamp turns on while the jumper is connected. Also, the change oil lamp turns off when the jumper is removed.

Result 2 The change oil lamp does not turn on while the jumper is connected to both sockets.

Result 3 The change oil lamp remains on while the ECM connector is disconnected.

Results:

• Result 1 - The lamp turns on and off when the ECM is bypassed. The circuit for the change oil lamp is OK. Proceed to Test Step 4.

• Result 2 - The change oil lamp does not illuminate when the ECM is bypassed.

  Repair: The vehicle's lamp circuit is not functioning properly. The lamp is probably burned out or there is a problem in the lamp circuit from the cab to the ECM. Check if the circuit protection for the vehicle has been tripped. Repair the lamp circuit or send the vehicle to the OEM dealer for repairs.

  Stop.

• Result 3 - The change oil lamp remains on while the J1/P1 ECM connectors are disconnected.

  Repair: The circuit between the ECM and the lamp is shorted to chassis ground. Repair the circuit or send the vehicle to the OEM dealer for repairs.

  Stop.

Test Step 4. Check the Operation of the ECM Output for the Change Oil Lamp

1. Fabricate a jumper wire with a socket terminal on one end.

2. Remove terminal 30 (change oil lamp) from the P1 connector. Insert the jumper wire (socket terminal) into P1-30.

3. Connect the J1/P1 ECM connector.

4. Connect one lead of a test lamp to the jumper wire. Connect the other lead of the test lamp to the positive terminal of the vehicle's battery.

5. Connect Caterpillar Electronic Technician (ET) to the service tool connector.

6. Turn the keyswitch to the ON position.

7. Access the "Change Oil Lamp" test in the special test menu.

8. Activate the "Change Oil Lamp" test. Observe the test lamp. The lamp should turn on when the test is active. Also, the lamp should turn off when the test is inactive.

9. Turn the keyswitch to the OFF position.

10. Return the wiring to the original configuration.

Expected Result:

The test lamp turns on and the test lamp turns off per the above description.

Results:

• OK - The test lamp illuminated during the "Change Oil Lamp" test.

  Repair: The lamp circuit and the ECM appear to be functioning properly. There may be an intermittent problem. Return the vehicle to service. If the problem persists, retest the circuit or send the vehicle to the OEM dealer for repairs.

  Stop.

• Not OK - The test lamp did not illuminate during the "Change Oil Lamp" test.

  Repair: Temporarily connect a test ECM. Check the output circuit of the ECM that supplies power to the change oil lamp when the test ECM is installed. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.

  Stop.