HARNESS AS-CEM 4877354 - Caterpillar

Note: The operator present switch provides two inputs to the Implement ECM and to the Transmission/Chassis ECM. If one ECM has activated the diagnostic code and the other ECM has not activated the diagnostic code, it is likely that the switch is operating correctly. This condition would indicate that there is a problem in the machine harness. In either case, perform this procedure in order to find the cause of the problem.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Test Step 1. CHECK THE INPUT CIRCUITS OF THE SWITCH FOR AN OPEN
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the connector of the machine harness from the switch.
At the connector of the machine harness for the switch, connect a jumper wire between the normally open (N/O) contact C (wire U767-BU) and the normally closed (N/C) contact B (wire U766-BR).
Disconnect the connectors of the machine harness J1 and J2 from the "Transmission/Chassis ECM".
At the machine harness connector of the "Transmission/Chassis ECM" J1, measure the resistance between N/C contact J1-63 (wire U766-BR) and N/O contact J1-64 (wire U767-BU).Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The input circuits to the switch are not open in the machine harness. Proceed to Test Step 2.
NOT OK - The resistance measurement is greater than 5 ohms. One of the input circuits to the switch is open or has a poor connection in the machine harness. Repair: There is an open or a poor connection in input wire to the switch U766-BR or input wire to the switch U767-BU. Check each input circuit of the switch individually in order to determine the circuit that has the problem. If the ECM modules have active diagnostic codes, a bad connection on the switch side of the splice connection for the signal wire is likely.If one ECM has an active diagnostic code, a bad connection on the ECM side of the splice connection for the circuit wire is likely.Refer to the complete Electrical System Schematic of the machine. Verify that all connection points in the suspected part of the circuits are clean. Confirm that all connections are secure. Observe that all connections are in good condition. Repair the machine harness or replace the machine harness. STOPTest Step 2. CHECK THE SWITCH GROUND CIRCUIT FOR AN OPENThe disconnect switch and the key start switch remain in the OFF position. The machine harness connectors remain disconnected from the Implement ECM and the switch.
At the machine harness connector for the switch, connect the jumper wire that was used in the last test step between the common ground contact A (wire A296-BK) and the normally closed contact B (wire U766-BR).
At the machine harness connector for the Implement ECM J1, measure the resistance between common ground contact J1-23 (wire A296-BK) and contact J1-63 (wire U766-BR).Note: Repeat the