ALTERNATOR GP-CHARGING 2591904 - Caterpillar

Illustration 1 g01127915
Key Start Switch circuit
This diagnostic code is recorded when the ECM reads the signal voltage of the key start switch and the voltage is too low. The possible causes of this failure are listed here:
The signal circuit in the machine harness is shorted to ground.
The ECM has failed. This is unlikely. The diagnostic code of CID 1834 FMI 04 will be logged in the internal memory of the ECM.Test Step 1. CHECK THE HARNESS.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the wire (wire 306-GN(Green)) from the keyswitch.
Disconnect the J1 and J2 machine harness connectors from the ECM.
At the keyswitch, measure the resistance between wire (wire 306-GN(Green)) and frame ground. Expected Result:The resistance is greater than 5000 ohms. Results:
OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. The ECM may have failed. Repair: It is unlikely that the ECM has failed. Exit this procedure, and perform this procedure again. If the failure is not found, replace the ECM. See Troubleshooting, "Electronic Control Module (ECM) - Replace". STOP
NOT OK - The resistance is less than 5000 ohms. The machine harness has failed. There is a short between frame ground and the signal circuit in the machine harness. Repair: Repair the machine harness or replace the machine harness. STOP