My car is kicking on the abs /low trac light and the brakes pulse as I come to a stop. when the car is almost completely stopped the abs will pulse for just a second, dry road and a soft normal stop, no reason for the abs to be on. it just started doing this today.

What is causing this? is the ABS wheels sensor going bad? or could it just be the abs relay switch? or something completely different?

 

I am fairly sure that you can have the ABS system scanned for trouble codes. No at home right now to check my manual, but maybe someone else can chime in.

 

yeah the haynes manual says it can be scanned at a dealer, does it read through the ALDL port? I can do that myself, I have a cable and freescan/datamaster but it isn't throwing the SES light.

EDIT: I checked the DTC code list on SHbox's site and there is nothing relating to the ABS.

 

The ABS codes are stored in the EBCM (located above the driver side kick panel) and can only be read using a Tech 1 scan tool via the ALDL port.

 

Check your abs connectors on each wheel (the front has one on the back of each hub and the rear is a single connector ontop of the diff). On mine I had a bad hub on the front and when the car would be coming to a stop only at low speed the Low Trac light would come on and the ABS kick in. Kinda scarey as if I was too close to some one at a red light I could roll right into them with the ABS going off.

 

the damn Stealership is going to charge $97 just to scan the damn thing, $97 for five minutes pushing a button on a scanner lloks like I might be doing an ABS Delete really soon! maybe a line-lock to boot

 

You can pull the fuse to disable the ABS system, but your normal brakes will function.

 

U can actually just unplug one wheel speed sensor and the ecm will see a fault and disable the abs system.

 

Not a good idea. The sensors are expensive, and if you unplug one you leave it open to the elements.

Pulling the fuse is a MUCH better, easier to access, carefree option.

 

Yeah pulling the fuse works but for the fact that the ABS system also controls the brake Bias and if you make back to back stops like I did today with and without there is a noticable difference in brake stopping performance.
You need a proportioning valve. So for the time being I am going to leave the system on with the occasional problem and after the first of the year I am ordering the SJM ABS delete kit since it looks like the best kit for the money.

 

Could you throw us the year and setup ?

 

Obviously something is commanding the valve to start and work, 1 theres a possibly a wiring issue thats showing the ecm that their is no wheel speed, which will command the valve on, From his discription one wheel is seeing a sudden drop in speed that is commanding the valvel on, Make sure all your wiring to your sensors are good a rubbed signal wire back to the ebcm could send false signal that a wheel is locking up. At worst the dealership will have to do a full diagnostic to see which wheel is at fault.

 

i do alot of abs/stability systems work, sounds like one of your wheel speed signals is dropping out. depending on how much the signal is dropping out it won't set a code. you have to drive the vehicle and record the wheel speed data and you will see one of the wheel speed signals drop out (at low speeds most of the time).

 

Have you even read my post as this identical issue happened to me earlier this year and as stated above it was a bad hub/speed/abs sensor. Check them out and you can even get one and replace the front two one at a time and see when the issue goes away. Odds are it's just one and on your rear wheels it's only one sensor and it's mounted on top of the diff. Check those front wheel hubs.

 

I had a problem with my ABS before I tuned my car for the cam swap.

Once I move after I start the car, the ABS INOP light comes on, or after I burn some rubber.

After I uploaded the tune, it never came back again.

Worth trying to reflash the PCM perhaps?

 

Hummm, ABS and PCM operate on completely different computers so I am not sure how reflashing the PCM could help any? An ABS INOP light would have nothing to do with tuning your car or a code thrown from a PCM problem.

 

I was just stating the situation I had and how it ended up going way.

I had the problem before, but after I flashed the PCM with the new tune it somehow disappeared.

I'm no PCM guru

 

DAVEOO hit the nail on the head. 99% of the time when the ABS acts up in this fashion there will be no codes. As far as the ABS computer knows there is nothing wrong except that the one wheel is locking up so it goes into action. Check to see if there is any play in the front wheel bearings. If there is replace it. If there is no play then you have a 50/50 chance of guessing the one thats causing the issue. Or you could have it diagnosed by someone with a scanner that gives live data.

 

The car is a 97 Formula, stock ws6 wheels/brakes
This problem is intermittent, I will pull the wheels this weekend to check for play and wiring issues. if that doesn't work I might end up saking it to the dealer to scan the EBCM
I am not sure if replacing one hub and testing it will work since it isnt a constant problem it might take a day or two to have the problem again?
Dave what you described in your original post is exactly what is going wrong, it is just a money issue or else I would replace both hubs and the rear sensor and be done with it.

Thanks guys I appreciate your suggestions, Gotta love the interwebs!

 

For the same amount of money the stealership is going to charge you, you can pick up a new hub assembly at Advance or AZ. Here are some pics of what the inner workings of the hub look like and how the abs sensor works, just a simple magnetic pickup. I'll bet you have an abs plug or lead loose or what I had which is the rear cover (silver dust cover with the abs sensor plug) was just slightly poped out causing false readings. The only pain is you have to pull the caliper and rotor off to get to the hub, but the hub is only bolted on by 4 bolts and I had em' off in 10 mins flat. Good luck.