Buick Riviera Traction Control Engaging

Traction control kicks in when you have no traction. If you have traction you can move forward/backward. If the front wheels are spinning you don't have traction. Then what the traction control does is cut a power going to the drive wheels until it regains traction then the traction control'll stop doing it's job for that moment in time. I remember driving a 98 Z28 with traction control and it gave a limited amount of slipping before it kicked in, the Riviera may be doing the same thing. It sounds like it's working how it was designed to.

Like I said in my post, the wheels ARE NOT slipping. Dry pavement, mellow acceleration, car moves a bit and the system kicks in... That's not how it's desinged to work. Also, the brakes are applied on this system - the FSM tell me so. :)

Dave

Approximately 11/16/03 18:13, Dave Barkley uttered for posterity:

Does it tell you how to check the wheel sensors to see if they are detecting slippage when they shouldn't be? If it ain't the sensors, the control unit would be suspect. Too bad you ain't in Kalifornia, all smog test stations now have dyno's where you should be able to trigger traction control at will. Otherwise dyno time tends to be a bit expensive.

Nah nah nah, you never explicitly said that they weren't slipping. In that case I agree that's not how it's supposed to work. Like you said before with the back sensors, I'd probably check those out...but then the back ones could be working right and the front ones might be reporting a higher spin rate. Time to check out the FSM. I'd like to hear what comes of this.

Ya got me... I didn't say that originally. I knew what I ment! :P When I get a chance I'm going to check out the rear sensors. I winder if I can hook up a DMM and check them out that way. If I read it correct, the system monitors the voltage (current?) that is produced at a pickup coil on each wheel. The frequncy of pulses (waveform?) is what conveys rotation speed. It'd be nice if it's just rusty parts that need a good scrubbin'. I also know where there's a riv in a boneyard that may have a donor brake control module. I'll let this group know my progress but I'm still hoping for a GM tech to say "oh yeah, I know what causes that".

Dave

It sounds like you maybe able to use a DMM but you're going to have to watch the display closely and have someone spin the tires. If I remember right the waves'll have a high and a low and from watching it you can see how rapidly the numbers change on the DMM. It'd most likely be easier on an oscilloscope, IMO. Maybe you could try disconnecting each one until you find the trouble one. Say it's one of the back ones and you have disconnected both of the front ones then it shouldn't happen anymore. Good luck.

Well, if you disconnect any of them, it's not going to happen anymore because it will detect the open circuit and disable the traction control..

Actually, I can't disconnect any part of the system... if I do the test that occurs at startup will detect component failure and disable the entire system.

As for the DMM, I have one that will display frequency... my goodness, try and watch the voltage change! Are you insane man! LOL

Dave

just want to mention that reading frequency can bite ya real easy on wheel speed sensors, you are better off reading the a/c voltage... your meter, like mine reads frequency very easily, with small peak to peak differences... I don't know why, but the abs modules are no where near as sensitive and have problems reading speed when a meter reads frequency no problem.Simply put the car in the air and measure the a/c voltage of the wheel speed sensors while turning it by hand...compare left and right only, not front to rear...I am almost sure you will find a problem in one of the front ones not reading at low speeds... makes the other wheel look like it's spinning and engaging traction control... I don't remember, but can you see the reluctor wheels on the front sensors???? look amd inspect them for damage if you can see them..... Bobo

This is great info... The problem is more intermittent lately. For a while it went away entirely but it's back. Your point is interesting because I've been suspecting the rear wheels, however I have might have good reason to suspect the front right. I'm not 100% sure of the time line however it seems this problem may have begun after I had the front right wheel bearing replaced. The bearing assembly for the Riviera includes the wheel sensor. The sensor may be borderline and if you're correct the voltage might reveal the problem. Theoretically, the voltage should be the same at all four wheels regardless of speed, and speed only effecting frequency. Resistance of the coil might also account for the problem as current differences might fault the system.

Fortunately the sensor system is sealed so debris cannot get in there however it also makes it where I can't inspect for physical faults.

I'm going to remove the front wheels and document the V, I & f, and make sure that the sensor wire is twisted properly to reduce the chance of noise... I know I should have got to this sooner but I'm trying to paint a new baby room! :)

No

The wheel speed sensor is an AC generator. The voltage and frequency will go up as wheel speed go up.