power seat/mirror problem

I am starting to troubleshoot a problem with my power seats/mirrors on my '98 Riv. Just posting this to ask if any of you had seen this problem before and if so, what it turned out to be.

The circuit breaker (under the rear seat) is overheating (to the point where it gave me 1st degree burn when I touched it).

So I reckon there's a short somewhere; I pulled the breaker (with pliers) and will find the short. My guess is it may be a problem in the seat/mirror memory box (the mirrors quit working too), the seat controls or a stuck limit switch. My second guess is the self-resetting breaker itself failed, and I plan to start troubleshooting this thing after I get a spare breaker.

Again - Just posting this to ask if any of you had seen this problem before and if so, what it turned out to be; would welcome comments and experiences.

Albertj

Albert,
Do you have or need the wiring diagram?
Is it the C2 25amp breaker in the RH Rear block that blew?

The front section of my power seat went out. Everything else works including mirror. Do I need just a fuse/breaker?



''

What do you mean by Front Section of Power Seat. i don't understand?

Hi Rick

I got my hands on a FSM set, so I think I'll be OK with the wiring unless there were revisions - I understand there were 2 editions for the 1998, I have the first edition.

So hopefully I'll work on it for some hours this weekend - unless Dear SPouse (DS) lets any of the blue smoke out, in which case she'll have to take it to the dealer because I'm out this week.

As to which breaker, yes. I removed the breaker. And I still ahve tender proof it was hot...

anyway...

As for RivParadise's comment, I'd check the wiring and the motor on the seat. Might be easiest to unbolt it and inspect wiring, and connect 12v to the seat (from a battery charger for instance) once you figure out which wires turn which motor, to see if it moves at all.

Albertj

I've got Rev 2 if you think you need it, let me know.
Also, if you look at the diagram, that particular breaker has power to it at all times. So it's possible for the breaker to just go bad and weld itself together.
You may get away easy by just having to replace the breaker and life will be good again, except for the burned fingers...Hope all goes well.

My 95 had a short circuit caused by the drivers door wiring harness rubbing against the window regulator. It rubbed through many wires and I think the power seat acted up sometimes also. I had to look on the inboard side to see the short. I don't know if Buick fixed this on the 98. Hope it helps good luck.

Thanks RIck and Don.

I will check the door harnesses for shorts - actually that makes a lot of sense - I dimly recall a service bulleting about the door harnesses but do not have access to TSBs to check. GM used to allow (free) access .

THinking about it RIck if the breaker is gettign hot there is probably a short - being welded together does not help. In some (low spec) cars for instnace a breaker is used to run automatic windows. The power window switch itself has a breaker - it snaps into position and allows 'window down' and when window reaches the limit the motor stops and current inteh circuit goes way up - causing the switch, acting as a breaker, to open.

So if the breaker is bad and overheating it seems there is a double problem. Part of problem is the breaker is bad. Other part of problem is the short is making the breaker hot. Real hot.

Basically what I learn from this thread so far is to look for shorts in places where wires have to move and maybe rub against stuff. Maybe if that is the case I can make a once-and-done fix by solder/heatshrink splicing and putting on a lyer of wire loom or friction tape.

Any other opinions or experiences?

Albertj

PS my fingers eems better today.

If we are talking about the same circuit breaker, it is hot at all time with B+ and orange wire runs directly from it to the Memory Seat/Mirror Module.
There is nothing in between except automobile.
In Vol.1 of my book it is Pg 8-1039 Body and Accessories Memory Seat Schematics.
CB # C2 (25a)

THanks Rick

So when I get home and troubleshoot, sounds like a good use of time is to find (a) a bum module (b) a bad breaker (c) a chafed wire. Not in that order. I suspect the order is look at module and wiring for physical damage first.

Thanks!

Albertj

Albert,
As I'm sure you know but I will offer my 2 cents here.
The breaker will only be commanded to close when you operate something connected to it's circuit such as the power seat, etc. So, when you push the power seat button the breaker closes, it is at this point that a breaker can fail and the internal contacts will weld shut, thus overheating the breaker and possibly melting some wires as the current is continuing to flow with a high resistance. That's the scenario for a breaker that has gone bad with everything else being O.K.. But you could also have the switch that commanded the breaker in the first place stick and cause the breaker to fail/overheat. Also, a possible shorted wire and lastly a Bad Module. You really can't start trouble shooting this problem until you get a new circuit breaker as the old one is definitely welded shut. Insert new breaker and feel if it clicks to engage, if so, remove immediately and find out what switch might be stuck or trace for short to ground.
Hopefully you will get away with just replacing the breaker and all will be good. But.......you know how these things sometimes go.

Thanks. I dont' have experience with self resetting breakers and I did not look at the wiring diagram yet (I'm not home this week) but it'll make a heck of a lot more sense to me now that you pointed this out. It sounds like you are talking about a relay in your note. I think it will make more sense, again, once I see that wiring diagram.

I would have thought the breaker was normally closed until it overheated, after all it only has 2 leads and is just a thin metal can. The relays (same fuse panel) have 4 leads and are marked as to which lead does what.

What I wonder is does the PS/PW memory module use SCRs to run the seats, in parallel with the seat switches, and did maybe an SCR fail giving me a short.

On my way home, or some time Friday, I"ll get a couple of those self-reset breakers (I brought the one with me that I pulled). If I put the new breaker in circuit and there is some problem elsewhere there's a chance (not a certainty) that I will fry the new one whilst figuring out what the root cause of my problem is.

Thanks again!

Albertj

The back end of the seat as well as the recline works. It doesn't work when you engage the front of the switch which does the up and down for the front of the seats. The back half of the switch still engages the back section of the seat. Won't work on the front. Thanks.

Albert,
Your right about me confusing the thermal breaker with the action of a relay. I had my head up my ass I guess. Disregard most of what I said, But I would get at least one new breaker for troubleshooting purpose's and replacement of the old one. The thermal breaker should have opened before it got that hot and it didn't.
Sorry for the confusion, when you get home and look at the wiring diagram the rest will make sense, hopefully. I didn't know you were out of town. Sorry,
Rick

Rick - I seriously doubt the cranial inversion and thank you again for your help. Rock Auto shows those breakers under "extras" for like $3.00 each, not a big deal and they are probably hanging on the racks at Autozone with the fuses.

Samuel - I suspect you have a dead motor or busted wire. There's no fuse for just the seat bolster only - unless some genius spliced one into the seat circuit, which is almost 100% unlikely. If I was you I'd set aside 2 - 4 hours to pull the seat out, unplug the wires and test things, then put 'em back together. My guess is you won't need that long, though, and that you will find (a) it jammed because the adjusting mechanism got dirty/rusty (b) something that someone jammed under the seat messed up the wiring or stuck in the adjuster (c) the motor just quit for some reason. Then having figured it out put it back together and find the replacement parts needed.

About that motor - the power seat and power window motors are 'permanent magnet' motors and depending on who actually made the motor, the magnets are glued or riveted in place. If glued, after a (long) while the glue can let go, then one or more of the magnets slip and the thing quits. What I do not know is if you can just replace the motor or if you're in for replacing all or part of the seat frame. By taking it apart you can start to make some good guesses about that. If you are not going to do the work yourself, if I was you I'd want to take your car to a relatively small independent body shop where you've seen one or more '60s or 70's era GM muscle cars (chevelle, GTO, whatever) in some state of repair or restoration - OR a dealer body shop. The point is that you are at the point where you are going to have to take it apart yourself or 'bite the bullet' and have it fixed and the problem there is that some dealer body shops are not going to want to bother.

As for me, I suspect I am calling Ed Morad for a replacement PS/PM memory module, unless I can take the module apart and repair the electronics. But I won't know until I take stuff apart. Rick has been more than generous with his time and comments and no doubt will keep me from really messing things up on this job. Thanks again.

Albertj

PS - for those of you curious about waht may be happening here, see http://www.ssousa.com/appnote050.asp. I suspect an SCR got overheated and failed - the car was driven a lot that week - and when they fail they short out. SCR = Silicon Controlled Rectifier, an electronic switch commonly used to use a little curent to switch a large current on/off. Or if the power window module uses on-board relays, over time the windings on those itty bitty relays can just die. Won't know what I am dealing with until I get it apart.

Thanks for the info. I think I will do a little work on it myself.

''

Albert,
How are you making out with the possible short or module problem. I'm interested to know what the problem is when you find it.
Thanks,
Rick

No problems and no progress troubleshooting, some progress overall.

As for the seat module, it's under the left front seat, access by removing all the plastic decorative covers of the front/rear of seat track, undoing the rear bolts and tipping the seat forward. There is a box on the floor under there, it's the airbag module. The seat module is on one of the seat frame bars.

I went to a pick-and-pull yesterday to find "anything" with memory seats, figuring that the modules are all probably made by Delphi or Valeo or whatever and I could cannibalize one for components to fix another. That pretty much failed only because I only found one vehicle so equipped - a mid-90s Continental - and could not find anything resembleing the memory module. That is, I looked under the seat, the dash, and in the trunk and did not find a box that looked likely. Knowing me I probably was staring right at it and just did not recognize. I did however pull a headlight knob *close to* the Riv's out of a Pontiac (have to figure out how to paint it), some replacement breakers from a few Grand Ams and a couple plug-in relays. They sold me the pile for $2.00 (buck eighty six plus tax). Weather was about 20 deg. F, overcast and blustery, so the yard was not at all crowded. It was good to be out to get used to the cold, but it kind of hurt the first half hour. I also have to be *very* careful not to get cut, so that combined with the cold put a damper on dismantling unfamiliar cars for me (if you want to know why PM me). I also helped another guy find a throttle body for his LeSabre (the cars are in neat rows but not organized really), any '96 or later n/a 3800 would work but there were not many '95 or later cars in the yard at all. We found one though, and it had the part and had not been there too long.

Some time was taken up with my spouse's school-related event at a local bookstore. I went to "support" her but what that meant was I colored in bookmarks for a fundraiser and read "Lemony Snicket" to some of her co-workers (who were not busy at the time) in character voices that I made up on the fly (I gave Lemony a deep gravelly voice with fake-y Boston accent, the portly red-headed restauranteur I gave a squeaky alto Yonkers drawl, and the drug store coupon shilling Santa I gave a shy, nasal, mid-tenor lisp). I was told it was pretty funny. Easy to find the hidden kid in stressed-out adults. On one of the snowman bookmarks I drew yellow snow (reindeer wizz) around the base to amuse the adults... one of the kids copied that...

Thinking about it, the pick-and-pull could probably make more money hiring high-school students on the weekends to dismantle and organize parts, as well as post them on the net. It would require some investment, though - have to build a Butler building or some such to hold the inventory and it might be tough to tell what to keep and what to trash.

Anyway, yesterday I also looked in service manual and on web for any schematic or other insight into the design and construction of these modules. No luck. But hopefully this evening I'll get it out at least. Maybe there will be a telltale but not a lot of ancillary damage. Again, I am suspecting that an SCR failed; they fail if they overheat, and that hopefully I can find the cause if any. They can be forced to fail from heat. They are not known to fail from age only but a combination of age and thermal cycling will do them in. Especially if the heat sinking deteriorates. And as well they eventually fail with the right combo of age and cycling. When I pull it I have to remember to write down which wire is which in the connectors, which will be a small PITA because there are four connectors with bunches of wires.

Albertj

So this afternoon I went out to look at the seat thing, after my Mandarin class (actually this is pretty cool - I am studying Mandarin Chinese at a local school run by volunteers in the local Asian community. They even gave me a Mandarin name, which seems to help a lot when I am introduced to negotiate business contracts, as well as socially). I have three used/unknown thermal breakers.

I figured the first thing I'd do was visually inspect wiring. So I pulled and tugged a bit to look around. Nothing seemed amiss. Then I put a breaker into the slot I left open - one of my pick-and-pull thermal breakers. I heard a little click, like a relay. I feel the breaker - it's cold. I wait a minute, feel it again. It's still cold. I look under the driver's seat. No blue smoke and no smells.

One thing I had forgotten about (talk about root causes) - before this thing failed we'd driven the car over 100 miles - back and forth to Pittsburgh (about 280 each way from here) then back and forth to New York City (about 260 each way from here. The seats quit on the New York trip. My son's buddy had her water bottle and some other stuff on the floor in her passenger footwell. Call her Miss It.

Anyway, so I still don't see/smell anything. Okay so now I need to figure out how to get the seet forward to expose the Torx(r) screws that hold the seat down. Looking under the seat to see if I can see the backs of the connectors, and thinking I need to get a meter probe to use as a jumper and how convenient that the orange line (hot) is nearby. Then it occurs to me - I still don't smell anything. If I had a problem with a bum SCR in the box, it's gonna start smelling when it gets warm. I feel the breaker again. No change.

So I think to myself, it's time to 'verify the condition.' Seemed like a waste of time but I used to work with an aerospace engineer (we'd hack cars) and that's the routine. So I push a seat switch.

The seat moves.

Hey, I'm alive by God's grace; I'll take a break when I can get it... this is maybe a break, depends on what I do with it.

So I hit the memory button.

Seat and mirrors move back to set position for each location (no surprise since the power to the memory box was not off, just the 25A line to the box for the seats).

I move the seat forward to expose the Torx(r) bolts anyway. And I look again under the seat.

Then it hits me.

There is a good chance that power connector for the seat motors might of got wet or scraped against the (grounded) seat frame when Miss It had her Nalgene water bottle rolling around on the floor of the car and maybe was sticking her feet under the seat. Because I am seeing Nothing that indicates a problem.

I left it hot (hot = breaker plugged in, battery connected) for a while (about 1/2 hour) to see what happened. Nothing.

I plugged in the old breaker to see what would happen, and left it hot.

Nothing.

I went back out suspecting I had a temporary short in that rat's nest of wiring under the seat, with a roll of electrical tape, looking for a wire, probably orange, with cut insulation. In a position that might of been stuck near a seat track. Yeah. And little black arc marks, too, maybe.

Nothing - at least nothing apparent after half an hour of poking around. What I did notice is that it's easy to contact the metal in the backs of the connectors, with wires open to the rear. Yeah. I used a little tape to lash the wires a little more so that as the seat moves they will stay away from the mechanism. The only thing that can be done with the connectors would be to fill the backs with a nonconductive silicone (i.e., bathtub caulk or blue RTV form-a-gasket). But that would make troubleshooting tough. And tape is not all that great an option for the connector backs because of their shapes and latches.

By the way - don't use crap electrical tape, be sure to use tape that's UL listed and even better get some 3M or other name brand and you'll find it works lots better.

So much for memory seat problems. For now, the score is RickW -1, Riviera Gremlins, 0. With an assist by Albertj. Thanks a bunch guys. I'll post an update if there's anything further.

Albertj

Good news and Good Luck.
We used to have gremlins constantly on Aircraft. Yeah I used work on Transport Catagory Aircraft.
That scary or what. Anyhow, gremlins are very common, more than the average customer would be comfortable with and we would First re-rack the component. That is disconnect and reconnect. 90% of the time all systems good to go and your on way Captain.
Rick

Hmmm.... I had an '89 Volvo wagon that had that sort of a problem with the ECM, eventually had to replace the ECM but until it failed hard, disconnect/reconnect would get it to behave. And "contact improver" spray did not hurt. Similar problem with the turn signal lights on a '99 Audi wagon I had, but fixed that by solder-plating the connectors (they moved when heated and arced, then carboned up from the arcing).

In this case I did not re-rack the component, but I left the power off of it for a week. Maybe that effectively re-set the Customer Replacement Encouragement circuit and I'll get another 198,000 miles of driving?

Albertj

The CRE circuit, I almost forgot about that.
Have a good flight, Captain.

I had the chance to take the seat out this weekend and first I wiggled everything around to see if there was a loose wire or something jammed in between the seat. I didn't see anything jammed or anything loose. I decided to try it once before removing and it worked! Mystery seat! For sure there was nothing stuck in there and I didn't see any wires loose but anyway, it works.

I figure (1) it reset the CRE circuit (yeah right) (2) maybe a switch was stuck and I did not know (not likely) (3) maybe the circuit hit an out of bounds state (plausible) (4) maybe a bad or dirty connector was arcing (plausible).

We will see.

Albertj

Sometimes there are no explanations or it's just not worth the time over analyzing.
As you said, remove connector, cleaned, reinstalled, all system operate normally.
Sign the log book and move on to the next problem