"TCS OFF" "ABS INOP" lights come one for no reason...?

**barberjd** · 02-16-2011, 09:16 PM

I have a 1999 Trans Am auto. When I first start up the car there are no lights or any issues that come on. I'll get down the road a little ways and all of a sudden, my TCS OFF and ABS INOP light up on my dash. Any suggestions where to start diagnosing a problem?

BTW... i push the TCS button and it will not respond and the light is off.

**Y2KPewterSS** · 02-16-2011, 09:19 PM

Have you changed tires recently?

**silverWS6** · 02-16-2011, 09:21 PM

Check the wheel speed sensors ( I think that's what they are called), small sensors behind the wheel/brake caliper area. One of the wires might be torn or almost tearing and that's when the pcm doesn't read it then it sends off the signal and those lights come on.

**98maro** · 02-16-2011, 09:27 PM

It could be a speed sensor. Or the ABS block. Mine had both problems.

If you are running bigger tires
Or you went for gears on the rear end.
That could be the reson,

**barberjd** · 02-16-2011, 09:31 PM

It was ran off the road and could have had something pull or tear the sensors. I will check tomorrow and see if anything looks unusual.

**Too Fast** · 02-17-2011, 02:22 AM

Wheel speed sensor/wiring is the vast majority of this cause. Just have to find out which one. Should be a relatively easy fix.

**laserredgt** · 02-17-2011, 02:27 AM

on my last car i had the brake inop light come on and it turned out being a brake hose that was torn and leaking...

**Too Fast** · 02-17-2011, 02:35 AM

Originally Posted by laserredgt

on my last car i had the brake inop light come on and it turned out being a brake hose that was torn and leaking...

And you didn't notice anything bad with the brake pedal? Must've been a real small leak.

**FutureWS6** · 02-19-2011, 09:29 PM

it means go fast.....right now

**02transamce** · 04-03-2011, 03:49 PM

mine came on today after going over a rough patch of asphalt.i guess i should check the rear wheels first or does that not matter?

**purplebat66** · 04-03-2011, 04:54 PM

i had my abs lights go on and i spent a fortune on a 1997 transam convertible that i had.The problem was the wire of the speed sensor please check that before anything, good luck.

**reaper ws6** · 04-03-2011, 08:56 PM

mine does the same thing. i just both a 01 trans am and wen i drive for a bit out of nowhere my tcs light comes on and the brake light and abs light. Also wen this happen's my tcs button does not respond. If you find the problem please let me know what it was.

**pajeff02** · 04-04-2011, 08:32 AM

Has anyone had their car checked with a brake scanner? The codes will not report on a regular scanner. I would head to the local parts store while the light is on and see if a code has been set.

**02transamce** · 04-04-2011, 08:38 AM

I scanned it with my basic scanner and got no codes.advance and the zone use the same scanner I have so I didn't bother with them
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**WICKEDLS1** · 04-04-2011, 09:58 AM

had the same problem a few days ago it ended up being that the bolt that holds the ground down on the dr. side front fender was loose. i tightened it up and havent had a problem since

**wooddaniel** · 04-04-2011, 12:20 PM

Mine did this intermittently for the entire time I owned the car... I never did figure out why it was doing it. Didnt really bother me though. No codes with a scanner here either. And even though my ABS light was on the ABS still worked.

**pajeff02** · 04-04-2011, 01:31 PM

Originally Posted by 02transamce

I scanned it with my basic scanner and got no codes.advance and the zone use the same scanner I have so I didn't bother with them
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A regular scanner does not read brake codes.

**SSwt00SS** · 04-04-2011, 02:25 PM

check the speed sensors. the dealership has a scan tool specifically to read them. it will tell you which one(s) are bad.

since the speed senors are discontinued, you will have to splice in the new connector to the one that came on the car. the guy at the parts desk can help you with that. take in the entire connector for reference. costs like $20 per connector (so no more than $80 if all 4 are bad). i had to do this to my '98 Ws6 that I used to have (passenger side front was bad).

it's pretty simple and straight forward.

**bberretta** · 04-04-2011, 08:52 PM

One thing to check is how much brake dust is built up on the sensor. Pull the 10mm bolt holding the sensor in and pull the sensor out. Clean it up and stick it back in. Too much interference with the magnetic sensor will cause it to misread.

Mine now trips only when I'm going down the interstate over long distances but that's because I've changed the rear, upped the gear, and put bigger tires on it. Tried my damndest to keep it close but evidently its just enough to trip both lights.

**MrKid** · 04-05-2011, 03:19 AM

Mine comes on and off. I read the codes with HPT and got 4 "restraint" codes. I can't remember what they all were, but one was a l/f speed sensor. Hasn't come on in three days, so not really concerned.