CHANGEOVER AR. 3H7176 - Caterpillar

Table 4
Troubleshooting Test Steps     Values     Results    
8. Check for Proper Operation of the ECM
A. Turn the engine control switch to the OFF position. Remove the electrical power from the engine.
B. Disconnect the J2/P2 ECM connectors.
C. Remove the wires from terminal locations P2-17 and P2-19 at the ECM connector.
D. Connect the J2/P2 ECM connectors.
E. Restore the electrical power to the engine. Turn the engine control switch to the STOP position.
F. Turn the engine control switch to the START position for at least 10 seconds. Then turn the engine control switch to the STOP position.
The 677-6Engine Starter Motor Relay : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the engine control switch is switched from the STOP position to the START position. The output remains on during engine cranking.
G. Use Cat ET to look for an active 677-6 diagnostic code.
H. Turn the engine control switch to the OFF position. Remove the electrical power from the engine.
I. Restore the wiring to the original configuration.
   
677-6    
Result: When the wiring was disconnected from the ECM, a 677-6 diagnostic code was not activated.
There is a problem with the wiring that is between the ECM connector and the harness connector that is for the start control relay. Repair the wiring. Verify that the repair resolves the original problem.
Result: When the wiring was disconnected from the ECM, a 677-6 diagnostic code was activated.
There appears to be a problem with the ECM. Perform the following procedure:
1. Turn the engine control switch to the OFF position. Remove the electrical power from the engine.
2. Temporarily install a new ECM. Refer to Testing and Adjusting, "ECM - Replace" for details.
If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM.