GEAR (40 Teeth) 7L7839 - Caterpillar

Illustration 1 g02139702
Connections of the steering position sensors
This diagnostic code is associated with steering position sensor 1. The FMI 04 diagnostic code is activated when the ECM detects the voltage of the input signal is below the acceptable range.Multiple position sensors are required for correct operation of the steering control. Each sensor provides an input signal to the ECM that indicates the position of the steering control handle. The signal 1 receives power from the 8 VDC power supply circuit and the 8 VDC return circuit from the ECM. The position sensor sends a PWM input signal to the Power Train ECM. The position sensor is a PWM sensor that operates at a frequency of approximately 500 80 Hz. The voltage of the signal range is from 0 to 5 VDC. The duty cycle of the signal varies from approximately 10 percent at the full forward position to approximately 90 percent at the full rearward position. When the steering control handle is at the center position, the duty cycle is approximately 50% and the voltage is approximately 2.5 VDC.The possible causes of this diagnostic code are listed:
The signal circuit is shorted to a ground source.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely. Check for an active MID 113 - CID 0041 - FMI 04 diagnostic code. A problem with the 8 VDC supply can cause this diagnostic code to be active. If the diagnostic code is active, perform the MID 113 - CID 0041 - FMI 04 procedure and clear the diagnostic code before performing this procedure.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. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1471 - FMI 04 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. Check the sensor
Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
Disconnect the machine harness connector from the sensor. Observe the status of the active FMI 04 diagnostic code. Expected Result:The FMI 04 diagnostic code remains active when the harness connector is disconnected. An FMI 03 diagnostic code has not been activated by the ECM.Results:
YES - The FMI 04 diagnostic code remains active when the harness connector is disconnected. The sensor is not causing the problem. Proceed to Test Step 2.
NO - The FMI 04 diagnostic code is no longer active when the harness connector is disconnected from the