Diagnosis Procedure

1. Confirm the customer complaint.

2. Determine if vibration is from front or rear (while brakes are still warm from confirmation test driving).

The following procedure will isolate the drum brakes from the rest of the hydraulic system by using the parking brake (PKB).

A. Drive the Tundra along a smooth, level section of road at approximately 40 mph - 50 mph.

B. Slowly apply the PKB while driving until the brake begins to engage and slow the vehicle. Do not apply the PKB past this point of initial engagement.

NOTE:
Remember with a foot PKB (on automatic transmission), the pedal must be pressed a second time to disengage the parking brake.

HINT:
When diagnosing a Tundra with a foot PKB, slowly apply the PKB until the first "click". Then press the PKB pedal a second time so it will disengage when it is released. At this time the PKB can be pressed to the desired level for continued diagnosis.

C. Hold the PKB at this point of initial engagement for a few seconds to slowly reduce the vehicle speed and allow adequate time to monitor the ride condition.

D. Disengage the PKB.

E. If brake vibration is felt during step (C), then it indicates that the rear brake drums are one source of brake vibration on this vehicle.

Refer to TSB No. BR003-02, "Rear Brake Vibration," for parts and repair information relating to Tundra rear brake vibration.

F. If no vibration is felt during step (C), then the front brake assemblies are the most likely cause of brake vibration on this vehicle.





G. Determine if TSB BROO4-02 has already been performed.