LEVER 4B0133 - Caterpillar

Illustration 1 g03111856
Connections of the EH Pump Displacement Sensor 1The CID 3778 diagnostic code is associated with the EH Pump Displacement Sensor 1. The position sensor is a PWM sensor that operates at a frequency of approximately 500 100 Hz. The position sensor sends a PWM input signal to the ECM. The duty cycle of the signal will vary from 8% to 92%.The value of the sensor duty cycle is approximately 92 in the negative rotation position. The value of the sensor duty cycle is approximately 8% in the positive rotation position. The FMI 04 diagnostic code means that the transmission ECM has detected the voltage to be below normal.The possible causes of this diagnostic code are listed here:
The sensor has failed.
The signal circuit in the machine harness is shorted to ground.
The ECM has failed. The ECM failing is unlikely. Test Step 1. CHECK THE SENSOR
Disconnect the machine harness from the sensor.Expected Result:The diagnostic code changes from CID 3778 FMI 04 to CID 3778 FMI 03.Results:
OK - The diagnostic code changed from CID 3778 FMI 04 to CID 3778 FMI 03. This condition indicates that the failure is no longer present. The sensor has failed.Repair: Replace the sensor.STOP
NOT OK - The diagnostic code remains. The failure remains present. The sensor is not causing the failure. Proceed to test step 2.Test Step 2. CHECK THE HARNESS
The sensor remains disconnected from the machine harness.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connectors from the ECM.
At the machine harness connector for the sensor, measure the resistance between the signal contact 3 (wire 746-PK) 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: If the cause of the active diagnostic code is not found, the ECM may have activated this diagnostic code in error. Verify that all possible causes have been investigated. If the cause of the failure is not found, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect the repair.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