What would cause ABS and Tire pressure warning lights to come on?

[Mad Bohemian]

I've got a 97 Grand Prix that is acting weird. When the car is cold, I can accelerate with no issue. Once the car is warm, if I accelerate normally like from a stop sign or light, the "Check Tire Pressure" and the "ABS" light comes on. Tire pressure is fine, brake fluid is up to snuff. If I shut the car off and start it back up the lights are off. Any ideas where to start looking? I thought maybe it was a loose wire, but that wouldn't explain the cold-no problem/warmed up- problem scenario...
Thanks guys!
MB

 

[FordMan77]

Could be a bad ABS wheel speed sensor in a hub. More likely a bad EBCM. Pretty sure ModuleMasters was the place to go for a quality rebuild on those.

If you have a place that can scan for ABS codes that would be a good place to start.

 

[digitalgpbandit]

'97 was a strange year electronic wise. There are no TPMS sensors in the wheels, iirc it measures it through the abs wheel speed sensor by measuring the wheel speed compared to the others or something like that. Your issue is in the ABS system. I would definitely try to find someone with a scanner that can pull abs codes. If you don't have access to one you can put your car up in the air and piggyback a volt meter to the wheel speed sensor. Have someone spin the wheel for you and it should read some voltage. If not that wheel speed sensor is dead. I would also check the wiring. It may be an issue where the wire is making contact while cold, but the engine heat makes it expand just enough to where it loses contact.

I constantly had issues with the abs system on my '95 Grand Am. I ended up living without it, but the way it acted it would always be off once I started. As soon as I went over 5-10mph the abs light would kick on.

Hope this helps

 

[Xerosiv]

If you have an android device, you can get a BAFX adapter and use Chevrosys (free app) to scan for ABS codes.
Could be wires, could be hubs, could be the abs module itself...

I just had my 06 ABS module repaired by this ebay vendor:
modulerepair on eBay

 

[Mad Bohemian]

Thanks guys . I think my brother has a scanner, this gives me a good place to start!

 

[danf]

I had this problem back in September? I think...

I had a wire that was rubbed through on one of the ABS speed sensors. I had zero luck with aftermarket scanners (the non-pro shop type) being able to read the ABS codes. I now have a Tech2 clone, and it told me which sensor was giving faulty readings, inspected all the wiring, and found a bad wire.

 

[Mad Bohemian]

well, here's an update on my issue..... My brother's reader didn't (or couldn't) read any ABS codes. I had been noticing any time I started the car with my foot on the brake I would hear this strange sound like a spring being twanged (is that a word? ) on a piece of plastic. At first it would do it after I drove 5-10feet, only occasionally. Lately I started noticing I would hear it as soon as I took my foot off the brake. My brother confirmed the sound came from my EBCM. So the problem persisted and was getting worse...until I change my startup routine. Now I start the car with my foot OFF the brakes wait for all the dash lights in the startup routine to shut off, then brake/shift and away I go...after about 3 days of doing that, the problem ceased. I can now punch it from a dead stop with no ABS , Tire Pressure lights (hopefully I didn't just jinx myself by posting this!~ ) Does that make any sense, why not pressing the brake during engine start would have that effect..??