Instrument Pod

Tail Light Warnings, Intermittant

Tail Light Warnings, Intermittant

My tail light warning light comes on, but my tail lights appear to be fine. Is the tail light warning light actually just a warning that *some* light is out? I know that one of my fog lights is out, so I was wondering if that could be triggering the warning light.

Thanks,
Mike
86 928S



The warning light also comes on if either of the rear (and maybe front - I forget) side marker lights are out. In cars of our vintage, the groundcontacts in these fixtures are often grunged-up. Does the warning light come on right after you start up and turn the lights on? Does the warning lamp extinguish after a few miles of driving? If so, next time you start up and the warning light comes on, stop, get out, walk around the car and look for the marker light(s) that is/are out. Usually, a sharp rap on the lens with your knuckles will light it up. You could get in the fender wells, remove the lamp assembly, and clean it and the connectors thoroughly and re-assemble - or you could simply replace the whole mess (which is not expensive, compared to some other things); in either case be sure to clean the surfaces where it grounds to the body - dust and random road crud can accumulate there and prevent completing the circuit to the marker lights.
-Tim



Don't forget the hatch mounted "third-eye" light if so equiped...it is in the loop!. Had a bad bulb in my '87 one time that drove me nuts. Would not always come on, except of course when I was looking at it. Took my wife driving behind me one night to discover it no worky sometimes.

Adam S.
'89 Black 5sp.



After bearing with months of putting up with the Tail Light Warning light coming on when the lights are "fine", I have finally decided to solve and repair this mystery. After cleaning all contact points and replacing the blubs (correct specifications), the problem was still there !!! But stangely I noticed that if I take out the left tail light (leaving the right hand side one in), the warning light does not come on, but if I do the opposite, (left in, right out) the light comes on (as you would expect). Even stanger is if I take out both bulbs, the warning light does not come on, but the stop light warning (that usually turns off when the brake pedal is pressed stays on !!

I'm not a wiz when it comes to solving electrical problems so any suggestion (appart from going to an auto electrician!!)

John
Sydney Australia
84 928s euro 5 speed



John,

I've just recently overcome this problem myself. My stop lamp warnning would not cancel. I replaced all of the stop light and tail light bulbs. This did not help. I cleaned all of the contacts and measured the resistance from the bulb sockets to the lamp check unit. None of this helped. Finally I took apart the bulb check unit and reheated each of the solder joints. This so far has solved all of those problems. I do have a lot of electronic experience in my past. If you don't, be cautious you can do more damage than good.

HTH
Ken Postma '86 928S



John,

It sounds like you have an electrical imbalance going on in your brake light warning module. It is a black box hanging out somewhere near the fuse box. Before replacing it though do one last thing. Buy two new identical brake light bulbs and see if this helps, although doubt it. When you see the price of a new module you will know why I suggested it.

If you have any friends that are good with a soldering iron have them take the warning module apart and resolder ALL the parts on the board. Solder shrinks with age and you might have a bad solder joint. It is worth a try.

Mark Grasser



I have a 1983 928S that had a warning lamp failure on the rear tail lamps. I traced it down to the side marker lamp wire. The side marker lamp wire passes though the inner rear quarter panel and over the years it had rubbed a bare spot on the wire to the body. I pulled the wire slightly and taped it with electrical tape, then pressed it back into the side wall of the rear body..... No more warning lamps on tail lamps that were just fine. The previous owner had lived with that warning lamp for 4 years.

The shorted wire was on the left rear side, but I checked both sides, perhaps the left side had more room for air to vibrate the wire since the gas cap is on the right side. I had change all the bulbs and cleaned all the lamp sockets twice, prior to finding this short. There is also a power antenna wire near this side marker lamp wire so be careful to get the right wire.

David Bezanson
1983 928S

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