Front Brake Calipers Locking

Hello, My '97 Camry sudenly started having problems with both front calipers locking up. When the car is stopped and recranked the calipers release and it can be driven normally. The car has ABS. I can understand one caliper going bad, but both locking at once. I don't want to replace everything (calipers, rotors, pads) and have it all happen again if something besides the calipers are the real problem. Any help will be greatly appreciated. Jeff

Maybe an issue with the vacuum booster. In a safe area with plenty of room to stop and preferable nothing to run into remove/block the hose or pinch off the hose that goes to the booster and see if the calipers still lock up. You will dramatical reduce your braking efficiency and will have to press a lot harder on the pedal to stop but it should help you narrow down the possibilities.

Another option is the combination valve is sticking and not releasing the brake line pressure, though honestly can't understand how shutting the engine off and on would reset it...sounds more like an electrical issue...tied to the ABS system perhaps?

Are you able to adjust the brake pressure to the point where they lock up (i.e. is there a particular brake pedal position where lock up occurs)? Can you feel the ABS system engage? If it does engage does it stay engaged until you are stopped?

Hi JD,
I'm not familiar with the combination valve (maybe by another name). How would I go about diagnosing whether it's the problem or not?

Thanks,
Jeff

Hi JD,
I'm not familiar with the combination valve (maybe by another name). How would I go about diagnosing whether it's the problem or not?

Thanks,
Jeff
There is also a repair manual for your vehicle stickied at the top of the forum. Or go to www.camrystuff.com

Good luck,

Sam

It's also called a proportioning valve. You also don't mention if you have all-disc brakes. The valve is not well diagnosed in the repair manuals and you need brake pressure gauges to test the pressures at the master cylinder versus the wheel cylinder.

I'd first check that the brake pedal is returning to its full height, the is the proper amount of pedal free play, and that the brake booster and master cylinder are not sticking in the bore. The pressure cant be released from the system if it doesn't fully return. Good luck!

i just put new master cyl on a car and it was from autozone and both front wheels locked up. come to find out i got another one from nappa it cured it. i knew both front rubber brake lines never colapsed at the same time. get them to lock up and jack it up and see if you can turn tires. but if both rubber lines have a split in the top you need to replace them anyway but i say master cyl.

First, thank you to all who contributed suggestions. They were all helpful in making a decision about what to do.

I waited several months since I made the repair before letting everyone know which part was the culprit so as to make sure that the solution I tried actually solved the problem. But it seems the master cylinder was what caused both front calipers to lock up at the same time. I think the piston was occasionally sticking in the bore.

Again, thanks for all the help.

Jeff

Great news. Thanks for posting the fix.