BREATHER GP 3920634 - Caterpillar

Illustration 1 g06113735
Schematic for the glow plug starting aid circuit
Not all connectors are shown. Refer to the appropriate Electrical Schematic.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Check that the fuses are not blown.
B. Inspect the terminals on the glow plug start aid relay and then inspect the connector on the flying lead from the relay. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Inspect the bus bar for the glow plugs. Ensure that the nuts that secure the bus bar to each glow plug are tightened to a torque of 2 N m (17 lb in). Ensure that the bus bar is not shorted to the engine.
D. Perform a 45 N (10 lb) pull test on each of the glow plug starting aid wires in the ECM connector.
E. Check the screw for the ECM connector for the correct torque of 6 N m (53 lb in).
F. Check the harness for abrasion and pinch points from the glow plugs back to the ECM.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring.
Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. The fuses are not blown. The bus bar is secured to the glow plugs and not shorted to ground.
Proceed to Test Step 2.
2. Check for Active Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Turn the keyswitch to the ON position.
Note: Do not start the engine.
C. Use the electronic service tool to select the "Glow Plug Start Aid Override Test" to turn on the power for the glow plugs.
D. Check for active diagnostic codes or recently logged diagnostic codes that are listed in Table 1.
Diagnostic codes
Result: No diagnostic codes are present.
There may be an intermittent fault in an electrical component between the ECM and the glow plugs. The problem may be inside an electrical connector. Refer to Troubleshooting, "Electrical Connector - Inspect" to identify intermittent faults.
There may be a fault in the glow plug switched power circuit. The ECM does not monitor the status of this condition.
Proceed to Test Step 5 to test this circuit.
Result: Diagnostic code 676-6 (2246-6) is active or recently logged.
Proceed to Test Step 3.
3. Create an Open Circuit at the Relay
A. Turn the keyswitch to the OFF position.
B. Disconnect the glow plug start aid relay.
C. Use the electronic service tool to select the "Glow Plug Start Aid Override Test" to turn on the power for the glow plugs.
D. Use the electronic service tool to check for active diagnostic codes. Wait at least 30 seconds for activation of the diagnostic codes.
Diagnostic codes
Result:A 676-5 (2246-5) diagnostic code is active with the relay disconnected.
Repair: Install a replacement glow plug start