08 Uplander Parking Brake Warning Light and Bell

My 2008 Uplander started showing the brake warning light in the dash with an exclamation mark through it some time ago when my wife was driving it. It never did that when I was driving it until today. The light comes on all the time now. When the vehicle is stopped (like at the traffic lights) it shows the annoying light without any noise. But when the vehicle is in motion the bell comes on continuously (same bell as when the seat belts are not bucked up). I suspect it may be some sensor that is dirty or malfunctioning because the feel of the van when driving it is normal.

I had a similar problem with a Ford van years ago, for which the dealer wanted to correct the problem for $100! Then I found out where the culprit sensor was for that and cleaned it - everything returned to normal. So this appears to be the same thing.

Can anyone comment on this issue, and if it is a sensor, where to find that sensor?

TIA,

quickcurrent

Have you checked the brake fluid level?

Thanks gmtech1.

Had not, just did. It was about 1/8" low in the master cylinder, just topped it up, but I doubt that is the cause of the problem!

Any other thoughts?

There is an electrical connector going to the master cylinder on the passenger side of the master cylinder. Could that be the sensor I am looking for?

That is the fluid level sensor for the master cylinder. If the light stays on. unplug the sensor and see if the light goes out. If so, the sensor is bad, or the float in the resivoir is stuck.

Pulled the sensor, no luck. The problem remains the same. Is there another sensor at the wheels?

Not that will turn on the red brake light. There is a switch for the park brake will turn on the light. You can check it by looking at it when you apply and release the park brake.

Thanks again gmtech1, I solved the problem with the bell coming on and the red brake light coming on.

When I applied the parking brake, the light went off. When I released it it cane back on!

So I went down looking for the switch you mentioned and didn't find the switch but found a wire with a blue sheath and a copper colored terminal with an L end that was dangling loose. My wife must have moved that connector over to the left so it touched metal in the area of the parking brake cable and shorted something causing my problem!

The question now is what is that blue sheathed wire doing there? Should it be connected to something or is it one of those wires for future/other feature not included in my Uplander, meaning that I should just put some electrical tape on it and tuck it out of the way? If you need it, I took a photo of it.

A pic would be good. It sounds like that is the wire for the park brake switch, and maybe the switch broke, leaving the terminal in the connector. When the connector contacts the the park brake assy, its is grounded and turns the light on.

OK, here is a photo of the wire

http://www.mediafire.com/download.php?7g4uui7p6rz6uw3

Thanks again bud.

Looked at the pic, and that is what happened. You'll need to replace the switch on the park brake assy.

Is this the part I need? (It's rather difficult to get in there to see what the switch looks like)

http://www.autopartsexpress.com/searchitem.epc?lookfor=SLS336

I'm not sure how that goes on there, but will no doubt be able to figure it out once I get the correct part.

Thanks again, gmtech1. You have been of tremendous help.

quickcurrent

Does not look like the ones I have seen, GM part# is 1264464, about 18.00. Hope this helps.

Thanks, I'll get one of those.

I tried getting one of those switches from the dealer and they had none in stock so I let it go ensuring that the end of the wire did not come in contact with any metal surfaces and all was OK until a few days ago, when three warnings started coming on:

Service ABS system
Service T/C system
Service Stability system

I thought it was that darned switch wire that had shifted, so I got down on my knees and had a look at what was there with a flashlight. I looks like the switch wasn't broken at all, just a copper part that the connecting wire hooks up to had come out of the plastic housing. So I took the bolt off to remove the switch housing and pulled the copper piece off the connector (wire) to figure out how to reassemble the switch. With a picture from the net I was able to put it all together, then re-installed it.

Now in addition to the above warnings I also get:

Parking Brake is on

Not bad, I've gone from 3 to 4 warnings!!!

So now I am wondering if all these warnings are being caused by the way I installed the park brake switch? Is the copper part of the switch that sticks out supposed to make contact with the parking brake pedal either when the parking brake is on or off? How is this switch supposed to work?

Or could these warnings be caused by something else? I've tried my OBD II reader but it gives me nothing. I think I may need a different device to read the codes causing these warnings! :-(

The ABS, Traction control and Stability lights are probably a seperate issue from the red brake light. You are correct, you will need a different scanner to read the ABS codes, a basic code reader will only read PCM/ECM codes. Would go ahead and order the new park brake switch and just be done with that part of it.

Would go ahead and order the new park brake switch and just be done with that part of it.

I'd do that but it looks like the park brake switch has nothing wrong with it, it had just come apart. I see nothing broken on it, no metal and no plastic has broken, so it's probably not going to do anything different with a new switch! What I am wondering is whether the switch is supposed to physically interact with the parking brake pedal at all when the brake is applied! (it has that piece of copper sticking out that looks like it should interact with the pedal!) When I just install it back without touching the brake pedal, I get the same Parking Brake Warning Light and Bell that I got before.

The switch is open when the pedal is released (not applied) the pedal assy contacts the switch at this time and "opens" it, you can watch this happen. When the pedal is applied, the switch contacts close, completing the circut and turning on the light. The switch is gounded through the park brake housing when it is bolted to it.

Thanks bud, that's what I needed to know.

I'll adjust it a bit later.

OK, I hadn't noticed it before, but the park brake switch actually has a small pin that goes into the floor to line it up properly as well as the bolt that secures it in place. That part is working fine now.

The other three warnings, I am still trying to figure out what to do about them.

I read that someone paid about $500 to have a similar problem fixed. At that cost, I'll remove the ABS fuse and live without ABS, T/C and Stability System, lol!

It seems that the ABS code reader isn't exactly easy to get and some don't support certain vehicles! Is there a way to methodically go about diagnosing the problem without an ABS code reader? I read about someone using a multimeter wired to the wire terminals of the sensors to find out which sensor was causing the fault. I've also read that, on this vehicle, the sensors are incorporated into the hub assembly (all of which has to be replaced to fix this problem - what a dumb ass design if that's the case!) and hence the $500 cost to get the problem fixed!

BTW, the fuse for the ABS on this vehicle is fine.

Any guidance to get me started would be appreciated.

Do the lights come on everytime? You can disconnect the speed sensor connectors and and measure the resistance, should be around 13k ohms, compare them side to side. If one is MUCH high than the other, its bad. Have seen lots of problems with the speed sensor harnesses. They break inside the insulation where it loops up from the lower control arm to the connector.

Really need to get the codes scanned to do a accurate diag though.

In Canada, we don't have the option of going to Autozone, there isn't one here. I'd pick up an ABS code reader if I knew where to get one at a reasonable price that will work on the 08 Uplander, but that doesn't appear to be an option either. :-(

So my next best option is to use the resistance trick since I have a multimeter sitting around. I'll have to do two wheels at a time as I only have two jack stands, but that shouldn't be an issue to compare them side to side. BTW, the warnings cycle on continuously one after another, like a ticker tape across the display on the dash.

If all else fails, I can break down and take it to the service garage, or, like I indicated before, just pull the ABS fuse and drive it without the frills. I've managed driving lots of cars without the frills in the past. But I'd prefer to get these systems restored if I can.

Thanks, gmtech1.

quickcurrent

Oops, just re-read my post, readings are usually around 1.3k ohms, not 13k. Sorry. Still, they should be the same side to side.

OK, I finally got around to jacking up the front end of this Uplander and had a look.

The brakes are mechanically fine with about half of the wear left on the pads, all pads evenly worn.

I found the small plate that used to be attached to the brake back plate loose and dangling behind the right wheel. On the left side it was still attached but quite rusty. I temporarily attached the small plate to the larger plate on the right side with a couple of small clips.

After disconnecting the sensor connectors I wasn't quite sure what resistance I was supposed to be measuring - across each pair of connectors coming from the ABS control module (with ignition to on or off) or across the connectors coming from the sensors inside the wheel hubs. I figured current is needed to have a resistance, so I must need to measure the resistance across the wires coming from the ABS control module with the ignition turned to on. Not sure how that measures anything about the sensors since they are disconnected at that time, unless information was stored in the ABS control module about them when they were connected! It would help to have a basic understanding of how this thing works.

Anyways, I cannot reach the connectors on the sensor side with my multimeter as the two probes do not physically fit in the connector together to reach the wires. So I measured the resistance across the connector wires coming from the ABS control module and they both flashed something over 1000 very briefly then started at around 550 and counted upwards to settle in at around 560 ohms. Neither gave me the 1.3 Kohms I was looking for, so I don't know if I didn't measure the resistance correctly or what I was supposed to do next, so I put everything back because I need to drive the van. I have not looked at the back wheels.

I've contacted the dealer about warranty coverage and was told that if the problem is within the wheel hubs, then it's covered under the drive train warranty, anything outside the wheel hubs is not. The sensors on the front wheels are definitely inside and an integral part of the wheel hubs, so if I can ascertain that it is a sensor, I'll get the dealer to do the work under warranty.

Any feedback on this would be appreciated.

On another note, I have the Uplander version with steel wheels and wheel covers. As all who have this type of fitting on their Uplander knows the wheels whoosh like crazy. Last year, before the vehicle went out of warranty I took it to the dealer 7 times (yes 7 times) to have them correct this noise and they were unable to do it. They reversed the tires on the rims, they replaced the wheel covers, they used the little plastic bits GM calls insulators, they conferred with the boys at GM Tech Support, and eventually they gave up and I ultimately gave up because I was sick of running back to them to fix something they didn't have a clue about, so I figured I'd live with the noise. The dealer was great about it, they tried everything they could, but GM failed me on that. Amazing that after 100 years in the business, they still can't design a proper wheel cover! Has anyone ever come up with a fix for that, short of replacing the steel wheels with alloys?

Anyone?

Check the Ohms of the wheel hub sensors AT the sensor connector. You may have to build some jumper wires to reach the terminals if you cannot get the meter leads to reach. Key off to check Ohms. Does not really matter though on the hubs, since they are disconected anyway.

Thanks, gmtech1, I'll try that even though I don't understand how that can work. I'll have to come up with a contraption to attach to the meter probes that will reach the connector terminals. It does make more sense to check the ohms across the wires coming from the sensors as that measures resistance by the sensors, but how do we get a measure of resistance if there is no current (since they aren't connected to any power source once the connectors are pulled)? V=IR; no V, no I, therefore no R !!!

Thanks, gmtech1, I'll try that even though I don't understand how that can work. I'll have to come up with a contraption to attach to the meter probes that will reach the connector terminals. It does make more sense to check the ohms across the wires coming from the sensors as that measures resistance by the sensors, but how do we get a measure of resistance if there is no current (since they aren't connected to any power source once the connectors are pulled)? V=IR; no V, no I, therefore no R !!!


Your meter actually provides a small amount of current when measuring resistance. You will get the results you need when you measure the sensor this way.

Your meter actually provides a small amount of current when measuring resistance. You will get the results you need when you measure the sensor this way.

Thanks, bud, I didn't realize the batteries in the meter powered anything but the meter itself. That should work then.

Tried again today to take readings from the sensor side but no luck. All I could get was a reading of 1 (same as when nothing is connected to the multimeter) from each sensor. So either this method doesn't work, the meter is not sending current to the sensors, or both are bad! I know I made good contact with the terminals on the sensor connector because the one on the right side of the vehicle comes apart so I could see the connector pins and touched the wires from the meter to them both, first in one polarity then the other to make sure I wasn't using the wrong one only. I attached thick braided wires to the probes of the meter so they made good contact there, so I am certain my method was sound. If the connectors are well attached to the brake cover plate this job is very tricky to do because one has to look from underneath and unless the vehicle is jacked up so that there is a good six inches between the bottom of the tires and the ground, there is no room to get one's head in there to look.

So now, I need to find a relatively inexpensive ABS code reader to take this any further as I've given up on reading resistances.

If anyone has any ideas, please let me know.

Are you sure your leads are good? This is the same process I use every day to check resistance in these sensors. Set the meter on Ohms and touch the two probes together, should read at or near 0.

Yes, that's what I get too, gmtech1, when I touch the leads, first it goes to some large negative number, jumps around for a couple of seconds, and finally settles in at 0.

I've used this meter for a few other jobs before with success, most recently this past summer to check the current output from a pool heater pilot generator. It just gives me nothing on the Uplander sensors' resistance. So it's likely it is not sending enough current (if any) to the sensors to get a resistance reading, I think.

Can anyone advise what abs diagnostic tools are known to work well on this vehicle?

TIA

OK, let me ask the question another way.

Has anyone used an Equus 3150B or 3160B or an Actron CP9580 or CP9580A AutoScanner Plus with success on an 08 Uplander to get ABS codes? I have read too many posts of people trying to get codes and getting nothing, so I am looking for a level of comfort that, if I go through the motions of buying one of these, I won't have to return it.

Anyone?