BASE AS 1451770 - Caterpillar

Illustration 1 g03794008
Schematic of the parking brake oil pressure sensorThis diagnostic code is associated with the parking brake oil pressure sensor. This diagnostic code is recorded when the Power Train/Chassis Electronic Control Module (ECM) reads the voltage of the sensor circuit as being abnormal. The circuit is shorted to +battery circuit.The possible causes of this diagnostic code are listed:
Wire G756-YL is shorted to the +battery circuit.
The sensor has failed.
Wire G756-YL or wire 202-BK is open.
The ECM has failed. Failure of the ECM would be unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0627 FMI 03 is active before performing this procedure.System Response:Warning category 3 is shown on the Caterpillar Monitoring System display.Test Step 1. CHECK THE SENSOR
Turn the battery disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
At the machine harness connector for the sensor, place a jumper wire from contact 4 (wire G756-YL) to contact 3 (wire 202-BK).
The status of the diagnostic code is active as the jumper wire is installed, and is not active as the jumper wire is removed.Expected Result:If the sensor is not the cause of the diagnostic code, the diagnostic code remains active. If the sensor has failed, the diagnostic remains not active.Results:
YES - The diagnostic code remains active the sensor has not failed. Proceed to Test Step 2.
NO - The diagnostic changes from an active state to an inactive state. The sensor has failed.Repair: Repeat this test "CHECK THE SENSOR" in order to verify that the sensor has failed. Replace the sensor.STOPTest Step 2. CHECK FOR AN OPEN CIRCUIT
Turn the key start switch and the battery disconnect switch to the OFF position.
Disconnect the J1 and J2 machine harness connectors from the ECM.
The jumper wire that was installed in the previous Test Step remains in place.
At the J2 machine harness connector for the ECM, measure the resistance from the signal contact J2-23 (wire G756-YL) to frame ground. Expected Result:The resistance that is measured is less than 5 ohms.Results:
YES - The resistance that is measured is less than 5 ohms. Proceed to Test Step 3.
NO - The resistance measurements is greater than 5 ohms. There is an open in the machine harness.Repair: Repair the machine harness or replace the machine harness. Verify that the diagnostic code is no longer active.STOPTest Step 3. CHECK FOR A SHORT TO THE +BATTERY CIRCUIT
The key start switch and the battery disconnect switch remain in the OFF position.
Remove the jumper wire that was previously installed.
The J1 and J2 machine harness connectors remain disconnected from the ECM.
At the J2 machine harness connector for the ECM, measure the resistance from the signal contact J2-23 (wire G756-YL) to all possible sources of +battery.Expected Result:The resistance for each measurement should be greater than 5 ohms.Results:
YES - Each resistance measurement is greater than 5 ohms. The harness is correct. The ECM