PISTON & ROD GP 1072198 - Caterpillar

Illustration 1 g01444757
Key Start Switch circuitThis 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 key start switch may have failed.
The signal circuit in the machine harness is shorted to ground.
The battery voltage of the machine is low.
The ECM may have failed. This is unlikely. The diagnostic code of CID 1834 FMI 04 will be logged in the internal memory of the ECM.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Test Step 1. CHECK THE CIRCUIT FOR THE SWITCH.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the J1 machine harness connector from the ECM.
At the J1 machine harness connector, measure the resistance from contact J1-34 (wire 585-YL) to contact J1-35 (wire 586-BR) with the switch in the Engaged position and the Disengaged position.Expected Result:The measurement of the resistance should be between 5 ohms and 5000 ohms for each switch position.Results:
YES - The resistance is correct for each measurement. The ECM may have failed.Repair: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace"STOP
NO - The measurement of the resistance is greater than 5000 ohms for one or both measurements. The harness or the switch has failed. Proceed to test step 2.Test Step 2. CHECK THE HARNESS.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the wire (308-YL) from the keyswitch.
Disconnect the J1 and J2 machine harness connectors from the ECM.
At the keyswitch, measure the resistance between wire (308-YL) 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: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "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