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Pinpoint Test B: The Parking Brake Will Not Release and/or Parking Brake Shoe Drag




Parking Brake

Pinpoint Tests

Pinpoint Test B: The Parking Brake Will Not Release and/or Parking Brake Shoe Drag

Normal Operation

When the parking brake release handle is pulled, the ratchet mechanism and return spring in the parking brake control releases the tension on the parking brake cables and conduits. The LH rear parking brake cable conduit and the springs on both rear cables provide the force necessary to return the parking brake shoes to their released position.

This pinpoint test is intended to diagnose the following:
- Parking brake control release handle
- Front parking brake cable and conduit
- Rear parking brake cable and conduit
- Parking brake shoes and hardware
- Parking brake control

PINPOINT TEST B: THE PARKING BRAKE WILL NOT RELEASE AND/OR PARKING BRAKE SHOE DRAG

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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 and TEST the system for normal operation.

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B2 CHECK THE REAR PARKING BRAKE CABLES

- Disconnect the LH cable from the RH conduit equalizer.
- Disconnect the front parking brake cable from the RH rear parking brake cable at the cable union.




- Disconnect the rear parking brake cables from the rear parking brake cable extension unions.
- 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 B3.

No
INSTALL a new rear brake cable. REFER to Parking Brake Cable - Rear Parking Brake Cable - Rear. TEST the system for normal operation.

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B3 CHECK THE REAR PARKING BRAKE SHOES AND HARDWARE

- Remove the rear brake disc. Refer to Rear Disc Brake Brake Disc.
- Inspect the parking brake shoes, hardware and backing plate.
- Are the shoes, hardware and backing plate in good condition?

Yes
GO to B4.

No
INSTALL new components as necessary. REFER to Parking Brake Shoes Parking Brake Shoes. TEST the system for normal operation.

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B4 ISOLATE THE FRONT PARKING BRAKE CABLE

- NOTE: The parking brake control take-up spool tab may need to be bent aside to allow the cable to be removed.

- Disconnect the front parking brake cable and conduit from the parking brake control.




- While holding the cable conduit, attempt to slide the cable inside the conduit.
- Does the cable slide freely inside the conduit?

Yes
INSTALL a new parking brake control. REFER to Parking Brake Control Parking Brake Control. TEST the system for normal operation.

No
INSTALL a new front cable. TEST the system for normal operation.

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