Diagnostic Routine A

Diagnostic Routine A

Diagnostic Overview

The Parking Brake Does Not Apply Or Does Not Hold Vehicle

Normal Operation and Fault Conditions

When the parking brake control is pulled, the parking brake equalizer pulls on both rear parking brake cables, which are attached to the parking brake actuators, and applies the brake shoes/pads.

Pinpoint Test

1. CHECK THE PARKING BRAKE CONTROL

1. Pull up the parking brake control handle.

Does the parking brake control move?






2. INSPECT THE FOLLOWING PARKING BRAKE COMPONENTS

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

1. Parking brake control

2. Front parking brake cable

3. Rear parking brake cables and/or equalizer

4. Rear brake caliper actuators

5. Rear brake shoes and/or hardware

Is any damage found or are any components disconnected?






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

1. Disconnect the front parking brake cable from the rear parking brake cable equalizer.

2. Pull up the parking brake control handle.

Does the parking brake control handle move?






4. ISOLATE THE REAR PARKING BRAKE CABLES (DRUM BRAKES)

1. Disconnect the rear parking brake cable from the rear extension cable at the affected wheel end(s).

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

Does the cable slide freely inside the conduit?






5. ISOLATE THE REAR PARKING BRAKE CABLES (DISC BRAKES)

1. Disconnect the rear parking brake cable from the rear brake caliper at the affected wheel end(s).

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

Does the cable slide freely inside the conduit?






6. ISOLATE THE REAR EXTENSION CABLES

1. Remove the brake drum on the affected wheel end(s). REFER to Brake Drum .

2. Disconnect the rear extension cable from the brake shoe actuator lever on the affected wheel end(s) and while holding the rear cable conduit, attempt to slide the rear cable inside the conduit.

Does the cable slide freely inside the conduit?