Pinpoint Test B: The Parking Brake Will Not Release
Parking Brake
Pinpoint Tests
Pinpoint Test B: The Parking Brake Will Not Release
Normal Operation
When the parking brake release handle is pulled, the ratchet mechanism in the parking brake control releases the tension on the parking brake cables and conduits. The front parking brake cable conduit and the springs on both rear cables provide the force necessary to return the brake shoes to their released position.
This pinpoint test is intended to diagnose the following:
- Parking brake cable(s) and conduit
- Parking brake control
- Parking brake control release handle
- Brake shoes and hardware
PINPOINT TEST B: THE PARKING BRAKE WILL NOT RELEASE
-------------------------------------------------
B1 CHECK THE PARKING BRAKE CONTROL RELEASE HANDLE
- Verify that the release handle is connected to the parking brake control.
- Is the release handle connected?
Yes
GO to B2.
No
CONNECT the handle and TEST the system for normal operation.
-------------------------------------------------
B2 ISOLATE THE PARKING BRAKE CONTROL
- Disconnect the RR cable and conduit from the body bracket, then disconnect the front cable from the connector.
- Disconnect the front parking brake cable conduit from the LR cable.
- Does the parking brake release?
Yes
INSTALL a new parking brake control. REFER to Parking Brake Control Service and Repair. TEST the system for normal operation.
No
GO to B3.
-------------------------------------------------
B3 CHECK THE FRONT PARKING BRAKE CABLE
- While holding the front cable conduit, attempt to slide the front cable inside the conduit.
- Does the cable slide freely inside the conduit?
Yes
GO to B4.
No
INSTALL a new front cable. REFER to Parking Brake Cable - Front Parking Brake Cable - Front. TEST the system for normal operation.
-------------------------------------------------
B4 CHECK THE REAR BRAKE SHOES AND HARDWARE
- Remove the rear brake drum, refer to Drum Brake System. Drum Brake System
- Inspect the brake shoes, hardware and backing plate.
- Are the shoes, hardware and backing plate in good condition?
Yes
GO to B5.
No
INSTALL new components as necessary. TEST the system for normal operation.
-------------------------------------------------
B5 ISOLATE THE REAR PARKING BRAKE CABLES
- Remove the brake shoes, refer to Drum Brake System. Compress the rear parking brake cable conduit locking tabs and pull the cable assembly through the brake backing plate. Drum Brake System
- While holding the rear cable conduit, attempt to slide the rear cable inside the conduit.
- Does the cable slide freely inside the conduit?
Yes
GO to B4.
No
INSTALL a new rear cable. REFER to Parking Brake Cable - Rear, RH Parking Brake Cable - Rear, RH and/or Parking Brake Cable - Rear, LH Parking Brake Cable - Rear, LH. TEST the system for normal operation.
-------------------------------------------------