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Dj
Dj, ASE Certified Technician
Category: Toyota
Satisfied Customers: 1910
Experience:  ASE Master Tech, 30+ years in automotive repair.
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Toyota Tundra: DJ. 2002 Tundra Ext cab 4.7 2wd. 95K miles.

Customer Question

Hi DJ. 2002 Tundra Ext cab 4.7 2wd. 95K miles. Back up or set parking brake. Release brake and travel forward. Brake pedal feels as if there is no or low brake boost. Bring it to a stop and press hard on brake pedal. A loud bang from the firewall area and now brakes feel fine. Sometimes comes back on its own sometines not???
Submitted: 1 year ago.
Category: Toyota
Expert:  Dj replied 1 year ago.
Thank you for requesting me.
Did you bleed and flush the brakes because of this problem or did the problem start after bleeding and flushing the brakes?
How rapid is the banging? Like a machine gun or less frequent, like banging a drum?
Does it only make this noise when you back up, then move forward? Will it make the noise under any other circumstances?
DJ
Customer: replied 1 year ago.
This situation has existed for the better part of a year. Almost forgot about it after the last time brakes were cleaned, inspected and adjusted. Now it is back and the brake fluid change was only performed, last week due to the age and color of the fluid. It is a single large bang or bump heard from the area of the firewall/booster at which point the brake pedal drops a bit and has " feel" to it. It is just a single bump or bang.
As I explained initially this bang or bump is heard under two circumstances. A, if I back up, top and then move forward and B,
If I set the parking brake, release it and travel forward or backwards. In either case the pedal feels like it has no boost or little boost, no progressive " feel " to it. Press the pedal harder and the aforementioned " bump" or " bang" is heard and felt, then brakes resume a normal feel. This may or may not occur again whether or not I back up or set parking brake
Expert:  Dj replied 1 year ago.
This is a weird one.
It sounds like a problem with the brake booster, but I can't see where backup up would make any difference.
If it were a problem with the ABS, the ABS light would come on and normally it would be more like a harsh rattle.
I'm out of ideas on this one. I'm going to put your question back into the expert pool. Hopefully someone has some recent experience with a problem like this.
Customer: replied 1 year ago.
A local garage is suggesting we replace the booster and master cylinder but again this truck has a mere 95K miles and it is 13 years old. I'm not in favor of throwing parts at it until we fix it. So, could it be master cylinder, could it be load leveler brake circuit. This is a system under the rear axle that senses the load in the bed and adjusts brake bias accordingly?