966G Wheel Loader and 972G Wheel Loader Power Train Caterpillar

CID 0794 FMI 07 Pressure Switch (Secondary Steering) Improper Mechanical Response - Test

Usage:

972G 1EW

CID 0794 FMI 07 service code can only be recorded if the optional secondary steering system is installed. The secondary steering system must be energized in the power train electronic control module (ECM) software via the Caterpillar Electronic Technician (ET) configuration screen. The power train ECM does this function with the pressure sensor switch inputs, a test switch, and a relay driver. CID 0794 FMI 07 service code is recorded if the power train ECM is commanding the secondary steering relay ON or the test switch ON, and there is not any pressure indicated by the secondary steering pressure switch. This is not an electronic fault. This is just an indication that the secondary steering system is not responding as intended.

Check the status of the fault.
1. If the CID 0794 FMI 07 service code is active, then it cannot be inactivated until the secondary steering system is activated and the secondary steering pressure switch indicates that there is pressure in the system.
1. After the engine is running, press and hold the secondary steering test switch for five to ten seconds in order to see if the CID 0794 FMI 07 service code changes to inactive.
  Expected Result: The CID 0794 FMI 07 service code does not change to inactive while the secondary steering test switch is depressed.
  Result:
  - OK - CID 0794 FMI 07 service code stays active. Proceed to Step 2.
  - NOT OK - CID 0794 FMI 07 service code does change to inactive while the test switch is depressed. STOP.

Check for other recorded service codes.
1. Other recorded service codes may indicate the reason for the improper operation of the secondary steering system.
  Expected Result: There are NOT any other recorded diagnostic service codes.
  Results:
  - OK - There are NOT any other recorded diagnostic service codes. Proceed to Step 3.
  - NOT OK - There are other recorded diagnostic service codes. Exit the CID 0794 FMI 07 procedure. Perform and correct the other recorded diagnostic service codes. Return to the CID 0794 FMI 07 procedure after the other recorded diagnostic service codes are corrected. STOP.

Check the battery voltage.
1. Check the battery voltage. The secondary steering motor requires a large amount of current. A weak battery may effect the operation of the motor.
  Expected Result: The battery voltage is correct.
  Results:
  - OK - The battery voltage is correct. Proceed to Step 4.
  - NOT OK - The battery voltage is NOT correct. Correct the cause of the low battery voltage and verify that the battery voltage is correct. If the conditions are not resolved, continue. STOP.

Check the secondary steering test switch.
1. Check the secondary steering test switch input to the power train ECM. If the switch is failed to ground, then the power train ECM believes that the operator is manually turning on the secondary steering system. If the pressure switch for the secondary steering system is not indicating pressure, then the CID 0794 FMI 07 service code will be active.
  Expected Result: The secondary steering test switch is correct.
  Results:
  - OK - The secondary steering test switch is correct. Proceed to Step 5.
  - NOT OK - The secondary steering test switch is NOT correct. Repair the harness or the cause of the failed circuit. STOP.

Check the circuit for the relay.
1. Check the circuit after the secondary steering relay from the power train ECM. The power train ECM does NOT drive the final relay that turns ON the secondary steering motor. There are wires from this relay for the intermediate secondary steering to a second relay which in turn drives the motor for the secondary steering. The power train ECM CANNOT distinguish if these wires are failed.
  Expected Result: The circuit after the relay from the power train ECM is correct.
  Results:
  - OK - The circuit after the relay from the power train ECM is correct. Proceed to Step 6.
  - NOT OK - The circuit after the relay from the power train ECM is NOT correct. Repair the harness or replace the harness. STOP.

Check the secondary steering pressure.
1. Check the secondary steering pressure.
  Expected Result: The secondary steering pressure is correct.
  Results:
  - OK - The secondary steering pressure is correct. Check the secondary steering pressure switch. Exit this procedure. Use the procedure for CID 0794 FMI 03 and CID 0794 FMI 04 in order to verify that the secondary steering pressure switch is operational. STOP.
  - NOT OK - The secondary steering pressure is NOT correct. Repair the cause of the incorrect secondary steering pressure. STOP.