Steve 88

I'm a new owner. When I drive my '88 AT with the lights on at night, I repeatedly see a warning light about my tail light along with the central warning. When I stop the car with the warning light still on, the tail lights appear to be functioning fine. The other day when I started cleaning bulb sockets I noticed that the marker light on one side had a broken "spring flap" (my words) and it had been replaced by a coil spring that rests between the bulb and the contact. The light works, but could this be the problem? If it could be the source, any advice on how to proceed would be appreciated. I don't see a detachable part and I think the rear light assembly is about $300 to replace.

Gretch

The warning system for bulbs does include the rear side markers too. If one of them is out the warning will be triggered. I believe you have to buy the whole side marker unit, if that is what you are talking about. The spring fix should not in itself cause the warning to trigger, although (at least on my 89 GT) some of the warning circuits are inductive and can be set off by errant radiation. I once had a very early "bag" phone that set my tail light warning circuits off everytime I hit the send button........

ew928

All 12 bulbs?
The central warning brain gets triggered if there
is a current load difference from one side to the other.
Urban legend is different brand bulbs side to side
can trigger the warning.

Mine was a severely corroded passenger rear marker.
And broken ground on same bulb holder.
Ernest (NYC)

John Struthers

Welcome to the headbangers ball.
I disagree -respectfully- with Gretch.
In theory the Lamp Control Unit (LCU) is a comparator device.
While the bulb in question will light drawing from the same -mirrored - circuit amperage/wattage/voltage, hopefully drawing a close enough approximation of
juice so that the LCU dosen't notice a measurable discrepancy between the mirrored circuits. I would think that the difference in line resistance because of the modified spring/pressure blade contact and the stock one would be enough to trigger the warning.
This area of the PO's electrical engineering magic - if it is the cause of your warn indication - is understandable , at least from the cost effectiveness point of view. (28 INTL lists the tail light assy for 87 - 95 MY at $100.0 0- used,
and $239.00 - new. As to the lens, I'm not sure if it is part of the tail light assy on the 87 - 95's. And sometimes like when you have to get something fixed quickly due to vehicle inspection or a upcoming trip you do what you have to.
This is all IMO.
Matched bulbs, new fuses, ground and connector checks are of course mandatory now and again, as is checking everything on the mirrored circuits up to and including the LCU which could cost you About $95.00 used, and $227.00 new.The questionable marker light goes for$70.00 new, $20.00 used.then there is the seal $5.00.
Good luck and let us know what you find.