RETAINER 0028639 - Caterpillar

Illustration 1 g02139504
Connections of the speed sensor for the steering motor
This diagnostic code is associated with signal 2 of the speed sensor for the steering motor. The sensor supplies two PWM signals to the ECM.The output of the sensor signals varies between 0 to 5 VDC. When a gear tooth passes close to the sensor, each sensor signal will register one period (1 hz). The voltage of the sensor signal will be dependent on the frequency and the duty cycle of the PWM signal. The ECM will monitor sensors signals in order to determine the speed and direction of the steering motor.The ECM expects the frequency and the duty cycle of each of the speed sensor signals to be similar. The FMI 08 means the ECM has determined the signal is not conforming to the cycle periods or patters.The possible causes of this diagnostic code are listed below:
The speed sensor is not mounted properly or the mount is loose.
An intermittent open circuit exists in the sensor signal circuit.
An intermittent short circuit exists in the sensor signal circuit.
The speed sensor has failed.
The ECM has failed. An ECM failure is unlikely.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 the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1470 - FMI 08 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. Check the sensor mountA proper mount for the sensor is critical for correct operation of the sensor.
Turn the key start switch and the disconnect switch to the OFF position.
At the sensor, check the condition of the mount. The sensor must be mounted properly and the mount must be secure. Expected Result:The mount for the sensor is loose.Results:
YES - The mount for the sensor is loose.Repair: Remove the sensor from the mount. Clean the mounting surfaces and install the sensor on the mount. Ensure that the sensor is correctly installed.Operate the machine in order to determine if the diagnostic code is still active. If the problem has not been corrected, proceed to the next Test Step.STOP
NO - The mount for the sensor is not loose. There does not appear to be a problem with the sensor mount. Proceed to Test Step 2.Test Step 2. Check the sensor circuits for an openThe disconnect switch and the key start switch remain in the OFF position.
Disconnect the machine harness connector from the sensor.
Disconnect the J2 machine harness connector from the ECM.
At the machine harness