GUARD AS 3807969 - Caterpillar

control relay.
Restore the wiring to the original configuration.For an electric start control, the correct resistance of the coil is 27.5 Ohms with the coil at 25.5 °C (78 °F).For an air start control, the correct resistance of the coil is 16.5 Ohms with the coil at 25.5 °C (78 °F).If the condition of the coil is suspect, replace the start control relay. Verify that the original condition is resolved.STOP
Not OK - A 677-5 diagnostic code was activated when the jumper wire was installed. The ECM did not detect the short circuit. Proceed to Test Step 5.Test Step 5. Check for Proper Operation of the ECM
Verify that the engine control switch is in the OFF position and that the electrical power is removed from the engine.
Disconnect the J2/P2 ECM connectors.
Fabricate a jumper wire that is long enough to create a test circuit across the ECM connector. Crimp connector sockets to each end of the jumper wire.
Remove the wires from terminal locations P2-17 and P2-19 at the ECM connector. Install one end of the jumper wire into each of these terminal locations.
Connect the J2/P2 ECM connectors.
Restore the electrical power to the engine. Turn the engine control switch to the STOP position.Note: The 677-5 Engine Starter Motor Relay : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the engine control switch is in the STOP position. The output is also off when the output for the crank terminate relay is activated.Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active.
Turn the engine control switch to the OFF position. Remove the electrical power from the engine.Restore the wiring to the original configuration.Expected Result:A 677-5 diagnostic code was not activated when the jumper wire was installed.Results:
OK - A 677-5 diagnostic code was not activated when the jumper wire was installed.Repair: The ECM did not detect the jumper wire that was installed at the P2 ECM connector. There appears to be a problem with the ECM. Perform the following procedure:
Turn the engine control switch to the OFF position. Remove the electrical power from the engine.
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.STOP
Not OK - When the jumper wire was installed, the 677-5 diagnostic code was activated.Repair: The ECM did not detect the jumper wire that was installed at the solenoid connector. The ECM did detect the jumper wire that was installed at the P2 ECM connector. There is an open circuit in the wiring harness 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.STOPTest