'87 - Inst Panel problems when dimmer is on

[TrueLyFE]

Hey everyone, again...

I posted about this a while ago before, but nothing came of it.

Basically, when my lights are on, my speedometer and odometer would stop working and my highbeam/turn signal cluster bulbs would be inverted. I found out that this changed depending on the dimmer level - I can drive and still have the odometer record proper milage if the dimmer is off, but of course I can't see how fast I am going - unless I use a flashlight or something . When on, neither work, the three lights invert, and the cluster still does not illuminate. The other lights in the car do (headlamp switch overhead light / ac-heater controls), however.

The dimmer switch has no effect except when the lights are off except for my blinkers, which go very slow (and sometimes not at all) when off, to normal speed when halfway to all the way on. Of course, with this problem, I can't have the dimmerswitch on when the lights are on right now...

The previous post I referred to talked about checking grounds, and all grounds seem okay. This is the only electronic problem I have as far as I can tell.

Having a pinout to the cluster switch would be a great help, because that would open things up to experimentation and I could probably solve my problem. My guess is that some cluster ground wire is grounding to the positive output of the dimmer switch. Having the pinout, I can verify some of these things...

Having the dimmer switch off sucks - I get no more audible alert about leaving headlights on, which is something I am really bad about Plus of course the aformentioned inability to have any inside lights at night, and the turn signal issue...

If anyone else has encountered this problem and has solved it, and can describe the fix, or if anyone has just some suggestions - I am totally open to it.

[TrueLyFE]

Nobody has any ideas on this?

[LeSabre97mint]

Originally Posted by TrueLyFE

Nobody has any ideas on this?

Hello

I'd recomend subscribing to AllData and taking a look at their wiring schematics. I think that there is a bad ground and the digital dash (it it digital isn't it?) is getting it's faulse ground through the dash lights.

Regards

Dan

[Loekee75]

Believe it or not, I had an old Dodge Dynasty with a similar problem, the gauges would not work at all unless the instrument dimmer was off (so I had the same problem, no lights at night to see how fast I was going) I tore open the dash and found that the problem was the harness that connects to the back of the instrument clusters. As soon as I pushed it in, everything went back to normal! Apparently the connector was broken back there because after time road vibrations would knock it loose again. That could be the case with your Lesabre.

[TrueLyFE]

Originally Posted by LeSabre97mint

Hello

I'd recomend subscribing to AllData and taking a look at their wiring schematics. I think that there is a bad ground and the digital dash (it it digital isn't it?) is getting it's faulse ground through the dash lights.

Regards

Dan

Already wasted $25 some months ago. There isn't much information for my vehicle regarding anything electical and therefore a total waste of money. Ground points are text only ("Front Passenger" is the limit of verbosity). I checked these all already before my wasted money verified.

My dash is NOT digital - it is the plain idiot light dash.

It is evident that there is probably a ground problem. I just haven't had time to completely rip the dash apart to fix it. Once my new(er) car is running, and if there is no easily accessible solution (ie. more than the dash pad), I will have to rip it apart and find out myself.

Originally Posted by Loekee75

Believe it or not, I had an old Dodge Dynasty with a similar problem, the gauges would not work at all unless the instrument dimmer was off (so I had the same problem, no lights at night to see how fast I was going) I tore open the dash and found that the problem was the harness that connects to the back of the instrument clusters. As soon as I pushed it in, everything went back to normal! Apparently the connector was broken back there because after time road vibrations would knock it loose again. That could be the case with your Lesabre.

I thought this too, other than that everything seems to work, and all the wires are in the harnesses. So mine most certainly is plugged in - looking straight on, if I remember, the right side controlled speed but I haven't tested with the other unplugged, as it is the ground (or power?) for all of the lights and ultimately probably wouldn't be helpful anyway. When both are plugged in, and my lights are on, my high-beam light will come on (when highbeams are off), still signifying that I have an issue with that ground.

--

Thanks for the ideas, I just wish someone else had this problem! (the only other thread I have found with it was from long ago, and an email to the person resulted in a response of "never fixed, got rid of" :-\)

[happydog500]

Originally Posted by TrueLyFE

Already wasted $25 some months ago.

I disagree about "wasted." Think of the education you got for the $25!
I've spent $475 (living on $695 month) and haven't got my interior lights working right.

[TrueLyFE]

Originally Posted by happydog500

I disagree about "wasted." Think of the education you got for the $25

You've got that right - I should stop wasting money. Good education.

I am completely honest about what I have learned using AllData that could help me - nearly nothing. For some it may be more useful, and may be useful for other vehicles, but certainly not this vehicle.

Anyway, good luck with your lights...running out of ideas for mine

[stuzman]

Originally Posted by TrueLyFE

You've got that right - I should stop wasting money. Good education.

I am completely honest about what I have learned using AllData that could help me - nearly nothing. For some it may be more useful, and may be useful for other vehicles, but certainly not this vehicle.

Anyway, good luck with your lights...running out of ideas for mine

If you don't mind spending the money for a factory manual, it WILL have the information that you need. I order all my manuals through www.helminc.com I see that your manual would run $133.00. As I've said, it's not cheap, but if you want to know anything about your car, it will be there. If it turns out that you'll have to pull the dash, you just as well have some good info for the wiring, ground locations, component locations, etc. Hope this helps!

[TrueLyFE]

Originally Posted by stuzman

If you don't mind spending the money for a factory manual, it WILL have the information that you need. I order all my manuals through www.helminc.com I see that your manual would run $133.00. As I've said, it's not cheap, but if you want to know anything about your car, it will be there. If it turns out that you'll have to pull the dash, you just as well have some good info for the wiring, ground locations, component locations, etc. Hope this helps!

This was my main plan, but didn't really want to spend over $70. A local Buick dealership will let me look at their books, but prohibit me from making copies - I can bring a camera in, that's about the extent. Even then, the only helpful thing I could find is harness pinouts... too bad Alldata doesn't have any.

Also, I see nothing for '87 LeSabre at Helm.

[LeSabre97mint]

Originally Posted by TrueLyFE

You've got that right - I should stop wasting money. Good education.

I am completely honest about what I have learned using AllData that could help me - nearly nothing. For some it may be more useful, and may be useful for other vehicles, but certainly not this vehicle.

Anyway, good luck with your lights...running out of ideas for mine

Just to add a side note here about AllData. My local liberary has a subcription and is available with a Lib card. Check yours.

Dan

[TrueLyFE]

Hello all - may have finally resolved the problem. Still don't know what the problem is / was, though.

Took apart my dashpad, then took 3 screws and the bolt out of the driver side dash. Shook it around, trying to see how it gets loose, then decided to try - no problems.

Started putting back together, and it is still working like how it is supposed to.

Going to go take it for a drive now (getting some replacement lights for burned out bulbs in my cluster as an excuse) and see how it works

Edit: Came back. Ripped apart now, still can't find where the problem is at. It is even more aggrivating now - the problem *was* gone and *can* be fixed but I don't know where it is and I can't find it. .....

Edit 2: Good news. I was able to get an online Chiltons manual for my car. It gave me the schematic for the dimmer switch. It helped me to make sense of the problem. The problem is either now in the wire that goes to my cluster, which can be directly replaced It is probably not with the dimmer ground connection, since only the cluster is affected. Same goes for dimmer positive. It isn't the dimmer switch, as a direct connection between positive and output (green to grey on the switch) still shows the same problem. It could potentially be the grounds to the cluster as well - but any of the fixes is easy. I am confident I can fix the problem now. Thanks all for your assistance, just took some perserverence!

[TrueLyFE]

This problem has been solved. Just in case anyone has this problem, here is a small review of what I did:

The problem was with the cluster grounds (LeSabre97mint was right on with this). I rewired every ground in the cluster (three in the left connector [pins 6, 12, 15], two in the right if I remember - they are all black). I also had to rewire the fuel gauge ground, since it is also connected to these grounds and ceased functioning. It is located, looking from the front of the car, on the left side behind the rear seat, which needs taken out to access. You may have to move the padding out of the way to see it. It is the black+white wire. I re-ran the purple fuel gauge wire (same location) just in case. It was that simple. Gauges work, and the cluster works with lights on. Dimmer works.

I kept the dimmer switch wire hooked up - my dimming works properly now with the bad grounds taken out. You may need to rerun this wire (gray wire from the dimmer switch) to the cluster, headlamp overhead light and AC / Heater control lights.

I couldn't tell where the grounds actually had problems, but it seems as if it was in the group of wiring behind the dash. All grounds seemed to be okay at their termination points, so something screwed up somewhere inbetween.

Hope this helps someone

[LeSabre97mint]

Originally Posted by TrueLyFE

This problem has been solved. Just in case anyone has this problem, here is a small review of what I did:

The problem was with the cluster grounds (LeSabre97mint was right on with this). I rewired every ground in the cluster (three in the left connector [pins 6, 12, 15], two in the right if I remember - they are all black). I also had to rewire the fuel gauge ground, since it is also connected to these grounds and ceased functioning. It is located, looking from the front of the car, on the left side behind the passenger seat, which needs taken out to access. You may have to move the padding out of the way to see it. It is the black+white wire. I re-ran the purple fuel gauge wire just in case. It was that simple.

I kept the dimmer switch wire hooked up - my dimming works properly now with the bad grounds taken out. You may need to rerun this wire (gray wire from the dimmer switch) to the cluster, headlamp overhead light and AC / Heater control lights.

I couldn't tell where the grounds actually had problems, but it seems as if it was in the group of wiring behind the dash. All grounds seemed to be okay at their termination points.

Hope this helps someone

Glad I was able to help!

Dan