trac light and Anti lock light
 

I noticed a month ago when i was hitting some bumps that my trac light and anti lock brake came on and flickered. It has probably only happened 3 times now. But today both lights are stuck on now, so what do i need to check? and how much is it going to cost...lol

Probably a wheel speed sensor or a connection to one of them.

Have the chassis codes scanned and it will tell you which wheel it is.

The most likely cause would be a bad wheel speed sensor. As it is intermittent, start by checking the connections and wires at each wheel hub.

I agree with both responses, above. The cost?......... About $90 for a GM dealer to scan ABS codes. Once the defective speed sensor is ID'd you can purchase a new hub bearing on the net for as low as $85 or so. Can you handle a "wrench" pretty well? Will save you a ton of bread.

Autozone will do it for free. Or find someone in your area with AutoTap, HPTuners, LS1edit, etc, that can scan things for you.

Like above, sounds like either a loose connection in the pigtail to the wheel speed sensor, or a bad pickup on the reluctor. They're fairly easy to replace as it's all one piece with the wheel bearing/hub. Fronts are a little different from the rears as you have to remove the drive axle nut. You can put a drift punch or screwdriver through the inspection hole on the caliper to hold the rotor still. Disconnect the pigtail, unclip it from the shield, then you can remove the hub bearing. Upon reinstall, torque the hub/bearing bolts to 70 lb/ft I believe.

With the rears, all you gotta do is remove the braking system (caliper & rotor), disconnect the pigtail, remove the 4 hub bearing bolts from the control arm, remove the hub bearing. Upon reinstall, I think the torque rating for the hub/bearing bolts is 50 or 52 lb/ft.

I've been having the same problems with mine. The low trac light comes on for a second and then the trac off and ABS lights come on right after and stay on till the car is turned off. And sometimes they both light up without the low trac light coming on first.

But I took my car to autozone and used the scan tool and got nothing. No errors or codes, just the all clear. But I just recently replaced the front drivers side wheel hub and I think the sensor has come loose or is bad.

I read somewhere that you have to use the "tech 2?" scanner that the dealership has to pull up those codes. But I could be wrong.

Any OBDII scanner can "read" (and subsequently clear) the codes. I read them with the software on my laptop. However a Tech 2 can read the PCM, write to the PCM with either updated flash/bios/ or other programming patches, command components on/off, do cycling tests, and run pretty much any diagnostic that the PCM allows. It can store vehicle specific information, then can be plugged into a terminal in any service department and communicate with the tech center in Warren, MI to download any VIN specific updates/changes.

But to simply get codes, any OBDII, GM ready scanner will get them.

The code readers at Autozone, Advance, etc. can only read the generic power train codes so, unfortunately in this case, they won't be any help.

You need a tech 2 or maybe a snap on scanner to read/clear chassis codes.

You dont notice any vibration or noise coming from one of the hubs when you turn the wheel?
Try driving slowly over a speed bump in a parking lot while turning the wheel, you might feel or hear something then?

Not true. I pick up BCM and other chassis codes with my software on my laptop. A lot depends on the type class of the DTC and what is supported in the PCM. Not all PCM's run the same parameters, allowing for certain support. But yes, for everything a Tech2 or Snap-On scanner works best.

A lot also depends on the type of DTC, or more commonly referred to as the type definition.

Type A is your main emissions related codes. These are primarily all your PXXX codes. The MIL will set on a first trip a fault occurs. It'll store a history DTC, freeze frame data, failure record, and will update the failure record each time the fault occurs upon test by the PCM.

Type B is also emissions related but here is the difference. The code is enabled after the first fault BUT is disabled if the second time it's run, it passes. It'll request the MIL be turned on on the second fault. Everything else thereafter is the same as a Type A

Type C1 is non emissions related, will request the "service vehicle" light (NOT THE MIL), on first fault. It stores the history DTC, DOES NOT store freeze frame data, stores a failure record upon fault, and updates the failure record each fault thereafter.

Type C0 is also non emissions related is the same as C1 EXCEPT it does not request any light on.

Most of your chassis related functions are gonna be a Type B or C1 code. There is a Type X code also, but that's more for diagnostic table information.

With that said, I do not know how OBDII CAN compliant vehicles (Which our Bonneville's are not) will run these DTC type definitions. Some '04 & '05 vehicles (GM, ford, Toyota)are CAN compliant but by 2008 all vehicles for sale in the U.S. must run CAN. CAN stands for Controlled Area Network and from my brief knowledge of it, it allows the subcontrollers to run their own tests and fualt codes that then report up to the PCM. This way the PCM isn't using all it's power to run everything. But that could be a vague and foggy description of it.

Yes, my AutoEnginuity scanner will read them also, but a general code reader such as is used by Autozone, etc. will only read the "P" codes. Let's try to keep this on topic of fixing their problem.

Victim here <raising hand>... I had the same exact thing happen to me... the lights would come on only after going over rough terrain....eventually, they would come on as soon as the car started...intermittantly, of course. Finally, the abs would kick on for no reasonable reason.

I didn't bother scanning it, after talking with my brother who works for an auto parts distributor... they sell a TON of new wheel bearings (hubs). I had both front hubs replaced last weekend at NEBF... problem is gone. This is an expensive fix if you go to a garage... Brianj spent $450 to have both done. Cost of the bearings alone are $115 (made in China) - $230 (made in USA) each in my area.

Because of the cost, it may be wise to have it scanned to see which one is acting up. I opted to replace both since I had access to members willing to do the work for me.

All of these answers are going the hard way and confusing. The solution is easy ...find which wheel bearing is bad and replace it. Problem solved. Original equipment is more reliable than rebuild parts typically.

yeah well back at home (3hours away), we have a shop back there that basically only charges for the parts and labor is free. So i just might get both replaced.

Ok, everyone else is probably right, but I can think of one other option that could cause this. Check your ABS connections at your rear wheels. If they were lose- they could have been disconnected as they rattled over bumps. They would trigger traction and brake lights- although I could be off on the thinking they trigger the exact two you are talking about.

I know this because I accidently disconnected one when I did my rear brakes once- and when i got back in the traction control wouldn't come on, brake and traction control lights were on. Might just need to be clicked in place. I could be wrong.

I was wondering if anyone had a picture of where that sensor is on the HUB..

Here's how to replace the front hub which shows the wiring for the speed sensor. As I stated way back when...check the wiring and connections first. The rear hub will have similar connections.
Wheel Bearing/Hub Replacement - Front

ok thanks, I'll have to check the connections tomorrow.

Ahem! That was for ONE side not both! After watching Don and Boosty change Tracy's at NEBF I'd say even a layman like me could do the switch....as a matter of fact if my pass side goes I'll be the one changing it this time saving me at least $300! Look at the pics I posted in Your Ride of NEBF of the work being done on Tracy's car. ;) http://www.bonnevilleclub.com/forum/...r=asc&start=80