DRIVE GP-FINAL 1102655 - Caterpillar

Illustration 1 g01958525
Connections of the shift rail position sensor 1 on a CX31-P600 with a dropbox
This diagnostic code is associated with the shift rail position sensor 1. This diagnostic code is recorded when the ECU reads the signal from the sensor as being shorted to the +battery. The sensor produces a PWM signal.Possible causes of the diagnostic code are listed:
The supply circuit to the sensor is open.
The return circuit is open.
The signal circuit is shorted to the +battery.
The signal circuit is open or the sensor is disconnected.
The sensor has failed.
The ECU has failed. This is unlikely.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 1823 FMI 03 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE VOLTAGE AT THE SENSOR.
Turn the disconnect switch and the key start switch to the ON position.
Disconnect the sensor from the machine harness.
At the machine harness connector for the sensor, measure the voltage between contact A (wire 709-OR(Orange)) and contact B (wire J765-BU(Blue)). Expected Result:The voltage should measure approximately 8 VDC.Results:
OK - The voltage is approximately 8 VDC. Proceed to test step 4.
NOT OK - The voltage is not approximately 8 VDC. Repair: There is a problem with the machine harness or the ECU has failed. It is unlikely that the ECU has failed.Proceed to test step 2.Test Step 2. CHECK FOR AN OPEN IN THE SUPPLY CIRCUIT.
The key start switch and the disconnect switch remain in the ON position.
The sensor remains disconnected from the machine harness.
At the machine harness connector for the sensor, measure the voltage from contact A (wire 709-OR(Orange)) to ground. Expected Result:The voltage should measure approximately 8 VDC.Results:
OK - The voltage measurement is approximately 8 VDC. Proceed to test step 3.
NOT OK - The voltage does not measure approximately 8 VDC.Repair: The supply circuit is not correct. Repair the circuit or replace the circuit.STOPTest Step 3. CHECK FOR AN OPEN IN THE RETURN CIRCUIT.
Turn the key start switch and the disconnect switch to the OFF position.
The sensor remains disconnected from the machine harness.
Disconnect the machine harness connector J1 from the ECU.
At the machine harness connector for the sensor, install a jumper wire from contact B (wire J765-BU(Blue)) to ground.
At the machine harness connector for the ECU, measure the resistance from contact J2-63 (wire J765-BU(Blue)) to ground. Expected Result:The resistance measurement should measure less than 5000 ohms.Results:
OK - The resistance measurement is less than 5000 ohms. The harness is correct.Repair: Check the circuit again. It is unlikely that the ECU has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECU. Prior to replacing an ECU, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, KENR8291, "Electronic Control Unit