SEGMENT 4V1228 - Caterpillar

Illustration 1 g03159457
Schematic of the parking brake pressure sensor circuit
This diagnostic code means that the Power Train Electronic Control Module (ECM) has determined that the parking brake pressure sensor voltage is above normal.This sensor is a Pulse Width Modulated (PWM) sensor that uses a frequency of approximately 500 Hz. The duty cycle operates from a range of 10% to 90%. See Systems Operation, "Sensors" for information regarding the operation and location of the sensor.Possible causes of this diagnostic code are:
Sensor signal circuit is open
Sensor signal circuit is shorted to +battery
Sensor failure
Power or ground circuit failure
ECM failure. The ECM is unlikely to failNote: The following test procedure may create other diagnostic codes. Ignore these codes, correct the original code, then clear these created codes. Ensure that the CID 2976 FMI 03 is active before performing this procedure.Note: Use a calibrated digital multimeter for this procedure.Test Step 1. CHECK FOR POWERThe sensor remains connected to the harness.
Turn on the disconnect switch and the keyswitch.
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along voltage supply wire (117-OR(Orange)) at contact 1.
Measure the voltage from contact 1 to frame ground. Expected Result:The voltage is 8 V.Results:
YES - The voltage is 8 V. Proceed to Test Step 2.
NO - The voltage is not 8 V. The +battery circuit in the harness has failed.Repair: Correct a tripped circuit breaker.If a circuit breaker has not tripped, replace or repair the harness.STOPTest Step 2. CHECK FOR GROUNDThe sensor remains connected to the harness.
Turn off the keyswitch and the disconnect switch.
Remove the 7X-1710 Multimeter Probe from the voltage supply wire (117-OR(Orange)).
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along sensor return wire (C241-OR(Orange)) at contact 2.
Measure the resistance from contact 2 to frame ground. Expected Result:The resistance is less than 5 ohms.Results:
YES - The resistance is less than 5 ohms. Proceed to Test Step 3.
NO - The resistance is greater than 5 ohms. The ground circuit has failed.Repair: Replace or repair the harness.STOPTest Step 3. CHECK FOR AN OPENThe switches remain off.
Disconnect the harness from the sensor.
At the harness connector for the sensor, connect a jumper wire between contact 2 (C241-BK(Black)) and contact 3 (K491-WH(White)).
Disconnect the harness connectors from the ECM.
At the harness connector for the ECM, measure the resistance between contact J2-40 (wire C491-PU(Purple)) and contact J1-45 (wire 118-OR(Orange)). Expected Result:The resistance is less than 5 ohms.Results:
YES - The resistance is less than 5 ohms. Proceed to Test Step 4.
NO - The resistance is greater than 5000 ohms. The harness is open.Repair: Repair or replace the harness.STOPTest Step 4. CHECK FOR A SHORT TO THE +BATTERY CIRCUITThe switches remain off.The sensor remains disconnected from the harness.The harness connectors remain disconnected from the ECM.
Remove the jumper wire that was installed in the previous step.
At the machine harness connector for the ECM, measure the resistance from the signal contact J2-24 (wire K491-WH(White)) of the harness to all contacts in the harness connectors for