I am having trouble recently with my cav. I just drive regularly and then for no reason the SERVICE, ABS, and TRAC OFF lights come on. I checked all the speed sensors and put it on my diagnostic computer but no codes came up. The brake fluid is full so this leaves me totally stumped. Does anyone have any ideas as to what may be causing this dilemma? Any help would be greatly appreciated.

Thanks
Patrick

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2003 Cavalier LS Sport "SHOCKWAVE"

Usually when these lights come on the problem is with one of the sensors on the front wheels.Either the sensor or connector. How did you check the sensors? Also you won't get ABS codes with an OBD11 code reader.

thats what i was thinking but i wasn't to sure. i checked the sensors by just wiggling them i know that don't do much but i just wanted to see if it made any difference. obviously it doesn't

We Ride Together, We Die Together...... J-Bodies For Life!
SPONSORED BY: Showstopper Tuning, JM Graphics
2003 Cavalier LS Sport "SHOCKWAVE"

Check resistance with ohm meter. Should be between 1500 and 2500 roughly. My experience with these sensors is usually just a bad connection at the plug, and a little wiggle like you said usually does the trick. If this does it put some dielectric grease on the plug also.

not trying to hijack here, but can you get to the sensor easily without removing the wheel? the reason i ask is id like to do this wiggle test on my gf';s car, but its freezing outside, and id like to just wiggle it and then drive/check it..
thanks in advance
kevin

I would say definitely a wheel sensor only because this happened on my '05. Exactly the same symptoms and the scanner said LF wheel sensor intermittent signal. You can get to the sensor from the back of the wheel. I second the motion to wiggle and clean and grease the plug. That solved my problem. Just be careful of breaking the plastic when you wiggle or remove the plug. If it's freezing outside, that plastic gets very brittle.

Check yopur charging system first......make sure your battery holds up to a load test and check alt. output...i have seen cars in that past with the same lights your are getting all to find out that the battery was original and was crap ( failed load test horribly ) ....if you ask me the OEM delco batteries are crap IMO....or are least were i live..

i have a brand new optima yellow top so that ain't the problem, and i pulled the front sensors, clened them with sand paper and checked the front ring gears but the dam things still come on so now i have no idea should i just buy 2 new sensors?


We Ride Together, We Die Together...... J-Bodies For Life!
SPONSORED BY: Showstopper Tuning, JM Graphics
2003 Cavalier LS Sport "SHOCKWAVE"

Check em with the ohm meter first. Also you should get low AC voltage just by spinning your wheel slowly

patrick myers wrote:I am having trouble recently with my cav. the SERVICE, ABS, and TRAC OFF lights come on. I checked all the speed sensors and put it on my diagnostic computer but no codes came up. Does anyone have any ideas as to what may be causing this dilemma? Any help would be greatly appreciated.

Thanks
Patrick

What did you used to check the codes with? the only way to get ABS codes is with a Tech II and connect to the ABS Module. I have a 2000 Sunfire and an 2002 Alero and when those lights come on you have lost a speed sensor in the wheel bearing Assembly (just checked this on my Sunfire and have to replace a rear bearing)

Stp

Could it be a grounding fault, similar faults were on two cars


http://www.j-body.org/forums/read.php?f=11&i=118227&t=118227

http://www.j-body.org/forums/read.php?f=11&i=118862&t=118862



Alont

To the one poster?

Why would you just buy two sensors, could be one of the back sensors as well. Could be a lot of things, broken tooth on the reluctar wheel causes ABS light to go on, bad sensor can, bad module, any problem with the ABS soleniods, or pump, there are a ton of other reasons to.

If your so deteremined to do it yourself, have a shop diagnose the problem, than you just replace the part.

PS if it is a broken tooth on a reluctar wheel, you might as well have a shop do it, because it involves a new hub assembly on most GM vehicles.
The axle nut is on there at 150ft I do believe, and the four bolts holding the hub on are torqued pretty tight, you almost need an impact for those to.




- 2004 Cavalier - 124k, owned since new

i thought it was a front wheel sensor because the problem occured about 3 weeks after i instaled new front brakes and rotors. there are no broken teeth on the relucter wheels. i was thinking of just going to a junk yard and pulling the front sensors just to see if that helped at all.


We Ride Together, We Die Together...... J-Bodies For Life!
SPONSORED BY: Showstopper Tuning, JM Graphics
2003 Cavalier LS Sport "SHOCKWAVE"

I'm with Alont on this one as I experienced the same exact problem with the same symptoms.

Check the main ground wire that goes from the negative side of the battery to the battery tray. The clip that bolts to the battery tray causes a break in the insulation, which allows the grounding cable to corrode. Your problem may be fixed by running a dedicated ground wire directly from the negative battery post to the stock grounding bolt on the transmission. If you have a multimeter, you can measure the resistance across that wire to check its condition.

You can buy a grounding cable with a side post terminal on it. You'll just need to fit a lug onto the other end.

I would try this before I went switching speed sensors and looking into changing CV shafts to change reluctor wheels.

[quote=Steve CardwellWhat did you used to check the codes with? the only way to get ABS codes is with a Tech II and connect to the ABS Module. I have a 2000 Sunfire and an 2002 Alero and when those lights come on you have lost a speed sensor in the wheel bearing Assembly (just checked this on my Sunfire and have to replace a rear bearing)

Stp

There are a lot of things that can only be diagnosed with the Tech II but my MT2500 with the new programmable cartridges do almost as much. Start up, go to domestic, ABS, put in the VIN and go.