Diagnostic Routine A

Diagnostic Routine A

Diagnostic Overview

The Parking Brake Does Not Apply Or Does Not Hold Vehicle

Normal Operation

When the parking brake control pedal is pressed, the pedal should move a short distance, with more pressure needed to apply the pedal as it gets closer to the floor, until the parking brake is fully applied. When the parking brake control is pressed, tension is applied to the front parking brake cable. This tension pulls on the RH (Right Hand) rear parking brake cable, which is attached to the RH (Right Hand) rear parking brake actuator, and applies the RH (Right Hand) rear brake caliper. At the same time, the tension in the front cable causes the RH (Right Hand) cable conduit to attempt to straighten out. This straightening effect causes tension that pulls the LH (Left Hand) rear cable, which is attached to the LH (Left Hand) rear parking brake actuator, and applies the LH (Left Hand) rear brake caliper.

Pinpoint Test

This pinpoint test is intended to diagnose the following:

- Front parking brake cable and conduit

- Parking brake control

- Rear parking brake cables and conduits

- Rear brake calipers

1. CHECK THE PARKING BRAKE CONTROL

1. Press the parking brake control pedal.

Does the parking brake control move?






2. CHECK FOR BROKEN CABLES

NOTE: Have an assistant press and release the parking brake pedal to help isolate disconnected cables or cables that do not move.

1. Inspect the following items for damage and correct connections:

2. Parking brake control

3. Front cable

4. LH (Left Hand) rear cable

5. RH (Right Hand) rear cable

6. Cable equalizer

7. Rear brake caliper actuators

Is any damage found or are any components disconnected?






3. ISOLATE THE PARKING BRAKE CONTROL AND FRONT PARKING BRAKE CABLE

1. Disconnect the front cable from the RH (Right Hand) cable at the cable union by releasing the locking tab.





2. Press the parking brake control pedal.

Does the parking brake control pedal move?






4. ISOLATE THE REAR PARKING BRAKE CABLES

1. Disconnect the LH (Left Hand) and RH (Right Hand) parking brake cables from the subframe brackets and the brake calipers.

2. While holding the cable conduit, attempt to slide the cable inside the conduit.

Does the cable slide freely inside the conduit?