JET AS-PISTON COOLING 3201545 - Caterpillar

Illustration 1 g02257015
Schematic of "Left Rear Wheel" speed sensor
This diagnostic code is recorded when the ECM compares certain machine conditions to the data received from the speed sensor of the left rear wheel. The ECM will issue this diagnostic code if the sensor data is not within specific parameters.
The speed sensor has failed.
The speed sensor is out of adjustment.
The supply circuit is open.
The return circuit (GND) is open.
The signal circuit (wire 769-BU(Blue)) is open.
The signal circuit (wire 769-BU(Blue)) is shorted to ground.
The signal circuit (wire 769-BU(Blue)) is shorted to the + battery.
The Brake ECM may have failed, but this situation is unlikely.Note: Check for other related diagnostic codes before performing the following diagnostic code procedure. If a diagnostic code for the data link exists, correct the diagnostic code. View the status of the other diagnostic codes and correct the other active codes.Test Step 1. CHECK THE VOLTAGE AT THE SENSOR
Turn the key start switch and the disconnect switch to the ON position.
Disconnect the machine harness from the speed sensor.
At the connector for the speed sensor, measure the voltage between contact A and frame ground.Expected Result:The voltage is 10 VDC.Results:
YES - The voltage is 10 VDC. Proceed to Test Step 3.
NO - The voltage is less than 10 VDC. Proceed to Test Step 2.Test Step 2. CHECK THE SUPPLY CIRCUIT.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness from the Brake ECM.
Measure the resistance from the sensor supply J1-69 (wire 799-WH(White)) at the ECM to contact A (wire 799-WH(White)) at the sensor.Expected Result:The resistance should measure 5 ohms or less.Results:
YES - The expected resistance measurement is observed. Proceed to Test Step 3.
NO - The resistance measured is greater than 5 ohms. The supply circuit (wire 799-WH(White)) in the machine harness has excessive resistance (open).Repair: Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK THE ADJUSTMENT OF THE SENSOR.
Check the speed sensor adjustment. See Testing and Adjusting, "Speed Sensor - Adjust".
Reconnect the machine harness to the speed sensor.
Operate the machine.
Check that the diagnostic code is active.Expected Result:The diagnostic code is no longer active.Results:
YES - The diagnostic code is no longer active. Adjustment of the speed sensor corrected the diagnostic code.STOP
NO - The diagnostic code remains active. Proceed to Test Step 4.Test Step 4. CHECK THE RETURN CIRCUIT.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness from the speed sensor.
At the machine harness connector for the sensor, measure the resistance between contact B (wire J765-BU(Blue)) and frame ground.Expected Result:The resistance should measure 5 ohms or less.Results:
YES - The resistance should measure 5 ohms or less. The return circuit is correct. Proceed to Test Step 5.
NO - The resistance measured is greater than 5 ohms. The return circuit (wire J765-BU(Blue)) in the machine harness has excessive resistance (open).Repair: Repair the machine harness or replace the machine harness.STOPTest Step 5. CHECK THE SIGNAL CIRCUIT FOR AN OPEN IN THE MACHINE HARNESS.
Place a jumper wire between contact B