VALVE ASSEMBLY 3S4904 - Caterpillar

Illustration 1 g00883387
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect the J1/P1 ECM connector and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Note: Refer to the Electrical System Schematic for further information about the machine wiring.Expected Result:All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Shorts in the Harness
Illustration 2 g00699950
ECM connector P1
Disconnect the J1/P1 ECM connector.
Disconnect all modules from the Cat Data Link.
Disconnect Cat ET from the service tool connector.
Measure the resistance between P1:8 (Cat Data Link +) and P1:9 (Cat Data Link −).
Measure the resistance between P1:8 (Cat Data Link +) and chassis ground.
Measure the resistance between P1:9 (Cat Data Link −) and chassis ground.Expected Result:The resistance should be greater than 20,000 Ohms for each measurement.Results:
OK - Proceed to Test Step 3.
Not OK - There is a short circuit in the harness or connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 3. Check Resistance Through the Harness
Illustration 3 g00699950
ECM connector P1
Use a suitable piece of wire to short J62:D (Cat Data Link +) and J62:E (Cat Data Link −) at the service tool connector.
Measure the resistance between P1:8 (Cat Data Link +) and P1:9 (Cat Data Link −).
Measure the resistance across the Cat Data Link at the other modules.Expected Result:The resistance should be less than 10 Ohms for each measurement.Results:
OK - The Cat Data Link is OK.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - There is an open circuit or excessive resistance in the harness or connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOP