VALVE GP-MAIN CONTROL 2851341 - Caterpillar

Illustration 1 g00825311
Schematic of the Primary Steering Pressure SwitchCID 0793 FMI 04 diagnostic code can only be recorded if the optional secondary steering system is installed. The primary steering pressure switch is connected to two inputs of the ECM. One contact is open and the other contact is grounded during proper operation.This FMI 04 means that the ECM has determined that both contacts are grounded.
Table 1
Primary Steering Pressure Switch    
Switch Position    417-GY Circuit
N/O
J2-10    484-YL Circuit
N/C
J2-6    
Low Pressure     Open     Closed    
High Pressure     Closed     Open    Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0793 FMI 04 is active before performing this procedure.Test Step 1. CHECK THE SWITCH
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the switch.
Turn the key start switch and the disconnect switch to the ON position.Expected Result:The CID 0793 FMI 04 has been replaced by CID 0793 FMI 03.Results:
OK - The CID 0793 FMI 04 has been replaced by CID 0793 FMI 03. The machine harness and the ECM are correct. Proceed to Test Step 3.
NOT OK - The CID 0793 FMI 04 is still active. Proceed to Test Step 2.Test Step 2. CHECK THE HARNESS
Turn the disconnect switch and the key start switch to the OFF position.
The machine harness remains disconnected from the switch.
Disconnect the machine harness connector(s) from the ECM.
At the machine harness connector for the ECM, measure the resistance from contact J2-6 (wire 484-YL) and contact J2-10 (wire 417-GY) of the machine harness to all the contacts that are used in the machine harness connectors for the ECM.Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
YES - Each resistance measurement is greater than 5000 ohms. The ECM has failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Testing And Adjusting, "Electronic Control Module (ECM) - Replace". Stop.
NO - One or more of the measurements were less than 5 ohms. There is a short in the machine harness.Repair: The short is between wire 484-YL and the circuit with the lowest resistance measurement, or the short is between wire 417-GY and the circuit with the lowest resistance measurement. Repair the machine harness or replace the machine harness. Stop.Test Step 3. CHECK THE OPERATION OF THE SWITCH (LOW PRESSURE)Note: Do NOT run the engine during this Test Step. This will cause low system pressure to the primary steering pressure switch.
Remove the jumper that was installed in the previous Test Step.
The machine harness remains disconnected from the switch.
Connect one lead from a multimeter to contact A (wire 962-OR) of the harness connector for the switch.
Connect the other lead from a multimeter to contact B (wire 417-GY) of the harness connector for the