TUBE-AIR 3560368 - Caterpillar

Illustration 1 g01045123
Schematic of the brake accumulator oil pressure switch for brake application
This diagnostic code is associated with the brake accumulator oil pressure switch for brake application. This diagnostic code is recorded when the Power Train/Chassis Electronic Control Module (ECM) reads the voltage of the switch as being above normal.Possible causes of this diagnostic code are listed:
(Wire X779-GY(Grey)) is shorted to the +battery.
The switch has failed.
The ECM has failed.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1612 FMI 03 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.System Response:The system will indicate low brake accumulator oil pressure. The parking brake will be forced to the engaged position. The parking brake will operate properly after the diagnostic code has been corrected.Test Step 1. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO THE +BATTERY CIRCUIT
Turn the key start switch and the battery disconnect switch to the OFF position.
Disconnect the switch with the diagnostic code from the machine harness.
Disconnect the machine harness connectors J1 and J2 from the ECM.
At the machine harness connector J1 and J2, measure the resistance from contact J1-38 (wire X779-GY(Grey)) to all possible sources of the +battery. Expected Result:Each resistance should be greater than 5 ohms for each measurement.Results:
YES - The resistance is correct for each measurement. The machine harness is correct. Proceed to Test Step 2.
NO - There is a short in the machine harness. The short is between signal contact J1-38 (wire X779-GY(Grey)) and the circuit with the low resistance measurement.Repair: Repair the harness or replace the harness. STOPTest Step 2. CHECK THE SWITCH
Turn the battery disconnect switch and the key start switch to the "ON" position.
Access the service mode. Place the CID 1612 FMI 03 on hold. Ensure that the diagnostic code is active.
Observe the status of the diagnostic indicator. Disconnect the machine harness from the switch. If the switch is not