Traction control...

[chev2002]

Quick question, which sensor sends the wheel slippage data to the EBCM? Does the ABS sensor play a dual roll?

I have a 2002 Impala LS, and my issue is that the traction control will crap out after driving for a bit. It will send a warning "service traction control" and disable itself as well as the ABS. If I turn off the traction control manually before I start to drive, it will not fail, but it will also no turn off the ABS system as it would with a normal failure. I am trying to pin this down to a sensor issue or computer issue. My new ODB2 reader is coming in soon since the crappy one I had broke, so I figured I would get some info in the mean time...

[Gems]

I'm no expert but I do know that there are speed sensors in each front wheel hub that send information to the EBCM... I must have one sensor going bad because every once in a while the "Traction Control" light comes up on the dash for a few seconds... I'm told I will need to replace the front wheel hub assembly that has the bad sensor... The question is how do I determine which hub has the bad sensor...

[tractorboy]

Gems I think that is normal, when your wheel starts to slip , traction control is displayed , showing that it was just employed. ....unless your wheel is not slipping, like in snow, sand, wet....etc. Those wheel bearings i would imagine are expensive. I had to replace one on my Celebrity and from GM it was $250 and that did not have a sensor.
chevy2002 what scan tool did you get ?

I was just thinking, if you have the option where you have the warning that your tire is going flat. That uses the same sensor. Apparently as your tire goes flat, it turns slower. So i would think that if the sensor is going bad you would have false " flat tire " warnings. Unless for the flat tire it uses a larger time base for sensing to cancel out wheel slipage.

[Gems]

I don't mean to hijack this post... Let me just reply quickly... There was no wheel slippage when my trac control light went on... The 2 times it happened I was slowly pulling out from a parking spot on dry pavement... I was going 5MPH max...

[billyo69]

My 01 has been doing it for 20,000 miles.I dont know which hub it is.But i read on this site that it has to be a front hub .I am not sure if that is true. I did change both my front hubs at 150k. I now have 178k.They tell me the dealer can scan it to see which hub it is.But i also dont know if that is true.

[BNaylor]

Originally Posted by billyo69

They tell me the dealer can scan it to see which hub it is. But i also dont know if that is true.

Thats correct. The GM dealer's Tech II will have no problems detecting flaky ABS sensors or properly reading ABS or traction control system DTC error codes. Also, scanners like the SnapOn MT2500 can do the same. The scanner must have the capability read GM ABS/Chassis codes.

Another thing you can do DIY is check is the electrical connector at the wheel sensor located in the hub. Look for corrosion or moisture, Also, with a multimeter measure across the wheel sensor terminals and look for a resistance value of around 1K ohms. Check all four wheels.

[chev2002]

I have the Equus 3030, it should be in soon to replace the other one I had.

http://www.iequus.com/item.asp?cid=7&pid=3030

It can read manafactrer DTC codes as well....I will see what it tells me.

I figured it would be the hubs, I just replaced the front ones a few days ago. I am going to check the abs sensor connects when the weather clears up this weekend. Hopefully the scan tool is in this weekend too....

[BNaylor]

Originally Posted by chev2002

I have the Equus 3030, it should be in soon to replace the other one I had.

http://www.iequus.com/item.asp?cid=7&pid=3030

It can read manafactrer DTC codes as well....I will see what it tells me.

I figured it would be the hubs, I just replaced the front ones a few days ago. I am going to check the abs sensor connects when the weather clears up this weekend. Hopefully the scan tool is in this weekend too....

It looks like a good scanner for its intended purpose and cost. Very similar to my Actron CP9145. However, you may encounter problems reading GM ABS/Chassis codes with these type scanners and the translation may be incorrect. I did not see in the specs where it definitely was ABS capable.

GM ABS/Chassis codes for a typical "W" body car running a ABS VI or higher system starts at C1211 and end around C1363 not counting serial data codes.

For example a left wheel sensor that is flaky may show a DTC error code of C1225 (Left Front Excessive Wheel Sensor Variance) with the proper scanner.

My Actron as good as it is will not read that code out properly.

At the Equus web site there is a place to input a DTC error code. Type in C1225 and see what you get. It is not in the Equus database which is the same programmed into their scanners.

Hopefully it works but there is no guarantee it will accurately diagnose GM ABS and traction control problems.

[Gems]

Originally Posted by bnaylor

Another thing you can do DIY is check is the electrical connector at the wheel sensor located in the hub. Look for corrosion or moisture, Also, with a multimeter measure across the wheel sensor terminals and look for a resistance value of around 1K ohms. Check all four wheels.

Thanks!! I will do that this weekend...

[billyo69]

Thanks bnaylor.I did check all the connections already.Is it true that it has to be one of the FRONT bearings to get the (service trac lite). The reason i ask is because i already changed the front hubs. The rears have 178k miles.The fronts have 20k miles.

[BNaylor]

Originally Posted by billyo69

Thanks bnaylor.I did check all the connections already.Is it true that it has to be one of the FRONT bearings to get the (service trac lite). The reason i ask is because i already changed the front hubs. The rears have 178k miles.The fronts have 20k miles.

Front hub/bearings only? Not according to the GM service manual. Any one of the wheels sensors at any wheel can give you the service traction control and ABS lights. However, the front ones are the most likely suspects. Because of the FWD the front end gets more of a pounding or wear n tear than the rear. I've seen a rear wheel sensor cause it but that was a wiring problem. A tech while installing struts damaged the wiring going to the wheel sensor. What brands hubs did you use on the front end?

[maxwedge]

Originally Posted by billyo69

Thanks bnaylor.I did check all the connections already.Is it true that it has to be one of the FRONT bearings to get the (service trac lite). The reason i ask is because i already changed the front hubs. The rears have 178k miles.The fronts have 20k miles.

As Bob said a Snap on mt 2500 will give you abs codes, also they have a troublehooter cartridge for the abs to narrow the problem down. A std mt2500 will allow you to monitor wheel speed sensor inputs. Careful with the codes, I have seen this and other scanners read false codes. Focus on the speed sensor inputs first, correct that issue, clear the codes and see what happens.

[billyo69]

I've seen a rear wheel sensor cause it but that was a wiring problem. A tech while installing struts damaged the wiring going to the wheel sensor. What brands hubs did you use on the front end?[/quote]


I put in ones made in mexico.The first ones had noises after 10 miles.They replaced them.Then these seemed OK but i suspect that i should have put in GM hubs. These mexico ones are garanteed for a year but i hate to keep replacing them.And now im not even sure if its the front ones.

[BNaylor]

Originally Posted by billyo69

I put in ones made in mexico.The first ones had noises after 10 miles.They replaced them.Then these seemed OK but i suspect that i should have put in GM hubs. These mexico ones are garanteed for a year but i hate to keep replacing them.And now im not even sure if its the front ones.

The only hubs I've used or trusted are the GM/AC Delco, BCA-Federal Mogul or Timken brands.

As suggested the best thing to do is run it on an ABS capable scanner to see which wheel sensor is flaky or at least narrow it down.

[josephk300]

I had the whole enchilada of issues with the traction contol system on my 01 Impala LS, 105,000 mi, starting with the warning lights, hearing the ABS come on from a stop for no apparent reason (i.e., good traction on clear pavement), traction system going into disable mode etc.. When it first started (around 95K), the dealer did not find any codes. I checked the ohms at each sensor and came up with the 1K ohms bnaylor recomlmended looking for, but still problems. After going back to the dealer at 105, they did find a code for bad ABS sensor in the right front. I ended up doing the job for less than 1/2 of the dealer price. I used BCA hub/bearing assy which is made by Federal Mogul vs the OE by AC Delco (also about 1/2 the price). Problem is completely gone, as well as a quieter ride (I guess the bearings were going too). Hopefully the BCA product holds up.