controller problems

[Rodney Robinson]

Hello

Thanks to everyone who helped us get started rving with our used Bigfoot two years ago. We got lots of useful advice here.

We are getting ready to rv again aftrer a couple of years off.

My tow vehicle now is a 2002 Yukon XL (flex fuel). It needed a brake controller and that is the beginning of a round of problems.

So everything was fine until I dropped off the Yukon for a Prodigy controller ar Bauers hitch in Minnetonka Minnesota.

Right after installation, some symptoms appeared. First we heard a scrapping noise. It sounded like it was coming from the left front wheel. I don't believe that his was a coinsidence, however at the same time I am wondering why or how could the new noise be connected with the new installation?

Next we heard the controller buzzing. Next everytime the controller buzzed the vehicle brake pedal would push up so hard the Yukon was almost impossible to stop.

Next, the abs light came on.

Now Bauers has installed thousands of hitches and hundreds of controllers.

I took the Yukon back to Bauers and dropped it off with a description of everything that was going on and I instructed them to replace the Prodgy controller with a "tried and true" Activator controller.

I picked up the Yukon last night. The abs light comes on intermittenly. The controller buzzes and pushes back on the brake pedal, but not so hard that I can't properly stop the Yukon. The scrapping noise is still there, it also is intermitten, but much reduced in noise and frequency of occurance.

Bauers said they had put the Yukon on thier computer and found that a wheel speed sensor was out.


Has anyone ever had this happen to them?

Has anyone ever talked to someone who had this happen?

Would someone care to "take a shot" at what all this might be? If so, please do as I am out of options.

Taking it back to Bauers is not an option.

My mechanic checked the front wheels and found shocks and joints to be o k. My mechanic has always been able to repair anything I presented him with, but now even he seems to be at a loss.

I just thought there might be enough controller experience available from the readers of this board to possibly be of some help.

Well thanks for listening.

[Suz]

As a non-mechanic, the first thing I would have done would was disconnect the controller and see if the same symptoms still presented.

I had a Prodigy installed on my 02 Envoy and never had a problem with it.

A quick call to a GM service center might shed a little light on it .. or it may not. Some dealers are better than others, but the call wouldn't cost anything.

If you don't get a definitive answer around here, you might try the Tahoe/Yukon forum

[Rodney Robinson]

Suz. Thank you

Good tip on the disconnect idea. We had to do that on the Prodigy, I guess I will disconnet the Activator as well.

Am going to that Yukon link you provided.

Free is always good. Maybe if I call enough service centers I can get some info.

Anyway you got me moving again after being totally stopped.

Thanks again.

Rodney and Maria

[Byron Kinnaman]

If it were me I'd simply take it back to people that installed the controller and tell them what the problem is. Then tell them to diagnose the problem. My guess it's an installation problem. They probably have grabbed the wrong wire someplace. If installed correctly there is no connection to the TV brake system except on the down stream side of the brake light switch.

[Suz]

If it were me I'd simply take it back to people that installed the controller and tell them what the problem is. Then tell them to diagnose the problem. My guess it's an installation problem. They probably have grabbed the wrong wire someplace. If installed correctly there is no connection to the TV brake system except on the down stream side of the brake light switch.

I'm with you, Byron. But since he stated that "Taking it back to Bauers is not an option" I thought I'd give him a few more.

I still think it was connected incorrectly. First clue is that they both do it. But then, I'm not a mechanic ... but maybe the person that installed it wasn't either.

[Byron Kinnaman]

The other option is as Bauers said something broke at the same time.

[Suz]

The other option is as Bauers said something broke at the same time.

Which a disconnection should confirm or debunk that thought.

[Rodney Robinson]

Thanks for the input Byron and Suz

I have started a simuliar thread at the Yukon site that Suz recommended.

Once the Prodigy was disconnected the brake problems stopped. I can't remember if the noise

stopped then. Seems like it was still making that scrapping noise even though it was disconnected.

Can't go back to Bauers as they had the vehicle twice with loser outcomes both times.

Will now check on Yahoo discussion boards and see if they have a mechanics forum.

Will be back later. Thanks again.

Rodney

[Byron Kinnaman]

I'd talk to a GM dealer service department.

From you're latest post it sure points to the controller NOT wired into the Yukon correctly.

[Bigfoot Mike]

Have you called Prodigy? FREE 800 number.
<blockquote>Prodigy Brake Controller
101 Spires Parkway
Tekonsha, Michigan 49092
Telephone: 1-800-STOP-YOU
http://www.tekonsha.com/faqprodigy.html
</blockquote>

[Brian B-P]

Yes, definitely check with Cequent (Tekonsha, the Prodigy people).

There are only four wires on these things, and although all of them should be done through GM-provided pre-wiring on this type of vehicle the vehicle may not have the desired pre-wiring, and even if it does the installation may still have been incorrect. I agree that the brake light signal is the likely culprit, as there are usually multiple wires which might work (from the controller's point of view), and only one which is correct (for the vehicle). I had four to choose from in my Sienna when I connected my Prodigy (which has no problems and causes no problems for the van).

Cequent sells Brake Control Accessories including...

O.E.M. Style Wire Harness for GM models equipped with trailer tow option. Harness includes GM connector, 3ft. leads and connector for hookup to Tekonsha® P3™, Prodigy®, Primus™ Brake Control

The one listed for a 1999 to 2002 model is part # 3025. If the Yukon has the tow package - and thus the built-in prewiring - this seems like the obvious and reliable way to go.

If tracing the wires myself, I would consider the Brake Control Wiring Harness Chart from Tekonsha; it didn't apply to my Sienna because it is not pre-wired (the Toyota listing in the chart is for the trucks and some SUVs).

I wouldn't get near a GM dealer with this until consulting with Cequent and personally checking all connections, as I would not have any faith that the GM tech would understand the problem... although they might be able to look up (in their service manual) the function of the wires to which the controller is currently attached.

It is sad - but not surprising - that the idiot at the shop happily connected another controller to the same wrong wires and didn't realize that the resulting behaviour was unacceptable. The different model of controller will likely place a somewhat different load on the truck's circuits (likely the one used for the brake light signal), and thus it's not surprising to me that the degree of the adverse effect is a little different.

[Rodney Robinson]

Thanks to all

Webguy, I made some progress by talking to Paul at Prodigy tech support. He immediately identified the noise as ABS (automatic brake system )

related. Also he connected the dots as to my wheel sensor and brakes pushing back and vehicle not stopping (without trailer). He said the Prodigy uses infromation from that sensor and so if the sensor has problems, maybe the Prodigy will not perform as planned.

Of course there is a lot still up in the air as I changed out the prodigy for an Activator 2, which is producing all of my original symptoms, plus abs light is on now too.

So thanks much for that Prodigy 800 number.

I will now focuss on that wheel sensor and replace it. Then go from there.

I have to say I have gotten a lot of help either directly for people here or from links and phone numbers I was gioven here.

Thanks again

Rodney

[jerry l elven]

If you run out of options as to the solution to your problems I would give Uhaul a call they are pretty helpful. At least when I ran into problems They were most informative.
Good luck Jerry.

[Byron Kinnaman]

I guess I'm a bit confused here. When I look at the wiring diagram (here) I see it connected to the brake light switch. I also see a warning about some Ford trucks with ABS braking. From that it would appear that it should NOT be wired into the ABS system.

[Rodney Robinson]

Jerry thanks for your input. I have gotten some help over the phone today, so not a bad idea.

Brian, I just spotted your post. I copied all the posts including yours and emailed them to my mechanic, I also filled him in on this GREAT site.

Brian's last sentence said to not go near a GMC service center, which I agree with. I emailed my mechanic, Scott, a Dunwoody grad, and asked if he wouldn't look closely at Brians ( and all the other ) post (s). Scott has wired up all my trailers, bucket trucks, cars, and SUV's and I expect to make some real progress tomorrow once he has slept on all he will be reading.

Brian also made the comment that he wasn't surprised by the somewhat changed behavior of the Yukon once the second controller was installed and he painted this picture of a worker, happily making the same mistake a second time, and this makes me feel that with all of you peoples help I just might get out of this mess after all.

Thanks Brian for that detailed response and thanks again to all.

Rodney

[Bigfoot Mike]

If you run out of options as to the solution to your problems I would give Uhaul a call they are pretty helpful. At least when I ran into problems They were most informative.
Good luck Jerry.

Rodney started at Bauer’s, his local U-Haul Franchise.

He wrote:
<blockquote>“Taking it back to Bauers is not an option.”
</blockquote>

[Brian B-P]

I didn't realize that Bauer's is a U-Haul franchise, but the conflict between this experience and positive recommendations for U-Haul doesn't surprise me at all: as franchises, they can be quite inconsistent. No matter what the U-Haul company knows about towing, the person at the franchise could have any level of knowledge or skill.

...I made some progress by talking to Paul at Prodigy tech support. He immediately identified the noise as ABS (automatic brake system) related. Also he connected the dots as to my wheel sensor and brakes pushing back and vehicle not stopping (without trailer). He said the Prodigy uses infromation from that sensor and so if the sensor has problems, maybe the Prodigy will not perform as planned.

I'm not sure that Paul's assessment made it through entirely clearly. The only information from the tow vehicle which is used by the Prodigy is a simple on/off indication of whether the brakes are being applied - which is intended to be from the brake light circuit - and the controller's use of this signal should not affect the tow vehicle.

• No matter what a wheel speed sensor is doing, or how the ABS is responding, this signal should be "on" continuously whenever the Yukon's brake pedal is pushed down.
• No matter what the Prodigy (or other controller) does, the ABS should not be affected by it.

Vehicle stability control systems (and even some distance-measuring cruise controls), which may apply the brakes even when the driver is not touching the pedal, make the "[b]are we really braking" question more complex, so with those features it is even more important to get the right wire. I don't have either of those in my tug.

Maybe I should have mentioned this earlier, but the [b]brake pedal pushing back is an expected result of the ABS relieving hydraulic pressure to the vehicle's brakes, and pushing the pedal back up to make up for the lost fluid - otherwise as the ABS took action the brake pedal would work its way to the floor. As a fortunate side effect, it makes the driver aware that the ABS is taking action.

[Rodney Robinson]

Was busy last night and we were gone fron this morning until now.

I can't believe it. We just used the Yukon for quite a few miles this morning and THERE ARE NO MORE SYMPTOMS AT ALL.

The ABS light is out. No scrapping noise. No buzzing noise and no brake pedal pushing back. Nothing. Yukon drives and acts like it

usually did before the controller installation.

With all the input and help I recieved here I feel obligated to come to some king of cure or resolution.

No one unplugged the latest controller, and Scott didn't come over and find a cure early this A M.

So to recap, I had all the negative symptoms for the last two or three or more days. Even with the changing out of controllers the

symptoms were still there. Today from the first there were no negative symptoms at all. Which is so so strange.

The only thing that happened was that yesterday was warmer than a number of previous days. That is the only thing that is different.

I have been telling everyone I have come into contact lately about this site and all the constructive help I recieved here.

I will continue to "test drive" the Yukon to see if any of the symptoms return.

In the meantime many thanks again for all the responses and all the effort everyone contributed.

If it ever comes to light, what it was that was causing all my problems, I will stop back here and give a full report.

I guess the best I can do for now to repay all of you is to "pay it forward" when ever I can.


Thank You

Rodney

[Byron Kinnaman]

One wonders if your brakes will still go into ABS. You might want to try to lock up the brakes on a gravel or dirt road.

[Brian B-P]

Scott (the trusted mechanic) probably has an On Board Diagnostics (OBD) code reader. Plugging that into the Yukon will show any stored diagnostic codes for the limited set of conditions which are covered by the OBD system; there are standard trouble codes, plus more specific to the manufacturer which are readily available for GM. One nice feature of OBD is that codes can be stored even after the problem conditions goes away, so there might be an informative indication still available.

Cars don't heal, but sometimes car computers work around problems, so it seems like the problem isn't there anymore. Like Byron, I would be a little concerned that there might still be an issue, even though there are no longer outward signs.

By the way, we don't need gravel or dirt to test ABS around here in this season; my whole drive to work is a demonstration of computerized traction control, and I can exceed available braking traction and trigger ABS at will for a significant part of that.