LINK AS 3W8401 - Caterpillar

Which Generate This Code:The sensor supply is a power supply that is internal to the ECM. The sensor supply provides 8 VDC in order to operate the sensors. The control module shall monitor sensor supply voltage for a low voltage condition. If the voltage drops below 7.5 VDC, an active diagnostic code is generated. If the voltage drop continues for 5 seconds, a diagnostic code is generated. The delay will prevent a diagnostic code from being logged when the machine is started. The diagnostic code will be cleared when the voltage is above 7.5 VDC for 5 seconds. The following sensors use 8 VDC: right track speed, left track speed, center brake pedal and decelerator pedal.This diagnostic code will be recorded when the ECM reads the voltage for the circuit of the sensor supply as being below normal.The results of this diagnostic code are listed:
All of the associated sensors will also log diagnostic codes.
The action lamp and the action alarm is ON.
This diagnostic code will cause the transmission to shift to NEUTRAL position until the diagnostic code is corrected.The possible causes of the diagnostic code are listed:
The supply circuit (8 VDC) is shorted to the ground circuit in the machine harness.
The ECM has failed. This is unlikely.Test Step 1. CHECK THE SENSOR.
Ensure that the diagnostic code is present. The diagnostic code should be active.
Observe the status of the diagnostic code.
Disconnect the machine harness from the sensor.Expected Result:The diagnostic code is NO longer active. Results:
OK - The diagnostic code is NO longer active.Repair: The sensor has failed. Replace the sensor.STOP
NOT OK - The diagnostic code remains active. The sensor is NOT causing the diagnostic code. Proceed to test step 2.Test Step 2. CHECK THE REMAINING SENSORS.
Ensure that the diagnostic code is present. The diagnostic code should be active.
Observe the status of the diagnostic code.
One at a time, disconnect the machine harness from the remaining sensors.Expected Result:For one of the remaining sensors, the diagnostic code is NO longer active when the harness is disconnected.Results:
OK - For one of the remaining sensors, the diagnostic code is NO longer active when the harness is disconnected. The sensor has failed.Repair: Replace the sensor.STOP
NOT OK - The diagnostic code remains active. The sensors are NOT the cause of the diagnostic code. Proceed to test step 3.Test Step 3. CHECK FOR SHORT TO GROUND
The sensor remains disconnected from the machine harness.
Turn the disconnect switch to the OFF position.
Disconnect the machine harness from the ECM.
At the ECM, measure the resistance between the contact of the sensor supply voltage and frame ground.Expected Result:The resistance that is measured should be greater than 5000 ohms. Results:
OK