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new memeber abs light tsc light brakes failed to engage completely today plz help

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veni85

New member
Ok guys i am new to this forum but work on cars frequently I bought my wife a 1999 pontiac grand prix gtp 3.8 super charged 232k miles almost everything new under the hood new transmision rebuilt super charger rebuilt block and heads

the abs light on the cluster is on the tsc on the center console display is always showing off OBD2 code says traction control torque request circuit malfunction code #P1571

today my wife went out washed the car started it to move it from the drive way pressed the brake pedal it had great pressure like normal she went to slip the shifter into reverse and the car took off once reverse engaged the brakes never once tried to catch once she stopped the vehicle turning off the key it sat for maybe a minute or less she started the car up and the brakes worked fine but the way in which the car took off and never even tried to stop pumping the pedal or slamming it to the floor scares me this is her dream car please any help is greatly appreciated as far as i have checked all vacuum lines are good wiring looks unbroken and not arching and pcm has been checked and comes back functioning properly

please guys this is my wifes dream car and she loves it but it almost got her killed today and i cant let her in this thing if its unsafe
 


The ABS/TCS light is likely due to a bad hub assembly, or one of the front wiring harnesses that comes from the hub to the main loom (follows the control arm- can't miss it) is damaged. These are the 2 leading causes of ABS issues.

As far as the brakes not engaging at all, well that would seem like a mechanical failure of the master cylinder. Did the pedal go all the way to the floor or was it stiff? Even with ABS disabled (which is currently is due to the ABS light) the brakes should function normal. I would check all lines for leaks and be sure the master cyl. is full of fluid.
 
master cylinder is full of fluid and no leaking brakes lines that was my first thoughts as well but the pedal stayed stiff when the brakes didnt engage as if the abs kept it from engaging at all but it had full pressure in the pedal still confused the heck out of me because as soon as the car was turned off and turned back on the brakes engaged just fine and have since

but on the hub assembly did a shake down on the front end all the bearings seem fine no loose wobble in it and its not making any kind of noise or vibration and theres no odd tire wear on the front tires so im wondering if there is a bad connection or broken wire or possibly a hub that is going bad but isn't showing the normal signs like a bearing grind or anything

is there another way to check the hubs besides just doing a shake down on it or driving it for a bit than taking the wheel off and checking it for excessive heat build up??
 
You can use a multimeter to check if the hubs are generating a signal. Basically just disconnect the harness at the hub, set meter to DC voltage and then spin the tire. If you get a reading then the hub is ok and you can start tracing the harness back from there. If the hub checks out then don't be surprised to find a bad/corroded wire a foot or more back into the harness. Happens a lot. If you find green or black colored copper wire showing then there is the issue. I think since it's a 99 the harness is 2 pieces and can be replaced from the hub to the main loom conenction up front. I know my 00 GP GT is like this as I went through the exact same thing.

But like Scotty said, if the EBCM is taking a dump then I'd start there.
 
She just washed it? How seriously did she wash the wheel area? Most likely excess wate on the discs getting dried off. Had she pressed harder it would have stopped.
 


no it was not a water issue on the rotors or calipers and the car has done it again with me behind the wheel and im 200lbs and smashing the pedal to the floor even with full pressure doesnt stop it i have spoken to one of the dealer guys hes checking in to see if its a recall issue with the ebcm and anti locks to see if theres a issue with abs keeping the car from engaging the calipers

the second time it happened my ase master tech buddy came over with a vacuum bleeder to see if there were any potential air bubbles in the brake system and after bleeding the brakes and getting full pressure sure enough it only happens on initial start up and doping into gear if its left sitting for a minute or so it doesnt do it

unplugging ebcm probably tomorrow car is temprorairily parked in the till weather breaks a bit


koRnhead said:
She just washed it? How seriously did she wash the wheel area? Most likely excess wate on the discs getting dried off. Had she pressed harder it would have stopped.
Click to expand...

theres not enough water in the world that could of kept the calipers from gripping the rotor completely but ty for your reply regardless
 
There is enough water to do what happened take it thru the car wash. First time you step on the brakes it will do that almost every time. But hey be a douche about it.
 
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