Pinpoint Test B: The Parking Brake Will Not Release
Parking Brake
Pinpoint Tests
Pinpoint Test B: The Parking Brake Will Not Release
Normal Operation
A ratcheting mechanism in the parking brake control keeps the parking brake applied until the release handle is pulled. When the release handle is pulled, the ratcheting mechanism in the parking brake control is released and the return springs in the parking brake shoes, and on the parking brake cables, return the system to the released position.
This pinpoint test is intended to diagnose the following:
- Parking brake cable(s)
- Parking brake control
- Parking brake control release handle
- Parking brake shoes and hardware
PINPOINT TEST B: THE PARKING BRAKE WILL NOT RELEASE
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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. TEST the system for normal operation.
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B2 ISOLATE THE PARKING BRAKE CONTROL
- Disconnect the front cable from the intermediate cable at the cable union.
- Does the parking brake release?
Yes
GO to B4.
No
GO to B3.
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B3 CHECK THE FRONT PARKING BRAKE CABLE
- Disconnect the front parking brake cable conduit from the parking brake control and from the frame bracket, then pull the front cable conduit through the opening in the vehicle floor.
- While holding the front cable, attempt to slide the front conduit on the cable.
- Does the conduit slide freely on the cable?
Yes
INSTALL a new parking brake control. REFER to Parking Brake Control Service and Repair. TEST the system for normal operation.
No
INSTALL a new front cable. REFER to Parking Brake Cable - Front Parking Brake Cable - Front. TEST the system for normal operation.
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B4 ISOLATE THE INTERMEDIATE PARKING BRAKE CABLE
- Disconnect the LH and RH rear cables from the intermediate cable equalizer.
- While holding the intermediate cable conduit, attempt to slide the intermediate cable inside the conduit.
- Does the intermediate cable slide freely inside the conduit?
Yes
GO to B5.
No
INSTALL new intermediate brake cable. REFER to Parking Brake Cable - Intermediate Parking Brake Cable - Intermediate. TEST the system for normal operation.
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B5 ISOLATE THE REAR PARKING BRAKE CABLES
- Disconnect the rear parking brake cables from the brake shoe actuators.
- While holding the rear cable conduit, attempt to slide the rear cable inside the conduit.
- Does the rear cable slide freely inside the conduit?
Yes
GO to B6.
No
INSTALL new rear brake cable(s). REFER to Parking Brake Cable - Rear, LH Parking Brake Cable - Rear, LH and/or Parking Brake Cable - Rear, RH Parking Brake Cable - Rear, RH. TEST the system for normal operation.
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B6 CHECK THE REAR BRAKE SHOES AND HARDWARE
- Remove the rear brake disc.
- Inspect the parking brake shoes, hardware and backing plate.
- Are the shoes, hardware and backing plate in good condition?
Yes
The system is operating normally at this time. The concern may have been caused by a seized or binding component. CLEAN and LUBRICATE the brake backing plate using the specified cleaner and grease. CONNECT all cables and INSTALL all components.
TEST the system for normal operation.
No
INSTALL new components as necessary. REFER to Parking Brake Shoes Service and Repair. TEST the system for normal operation.
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