Map light rewiring on 1990 convertibles

[Guest xerxes]

Is there a way to rewire the map lights to come on automatically when the doors are opened on the 1990 convertible? This would really be nice as there is not very much light inside when the doors are opened at night. Of course, it would also be great if this did not cut out the switches on the mirror so they could be used individually when needed.

Thanks in advance!

[KDirk]

Not sure this can be done with the stock rear-view mirror. The compass rear-view from a early 90's Roadmaster that some of us have converted for use in the Reatta has a 4 wire connector. The 4th wire is a second ground path for the integral map lights. When grounded, it causes both map lights to illuminate. This lead in turn could be wired to the switched ground on the courtesy lamp circuit so when the doors or open the map lights will double as a "dome light". Of course, they would also operate when the panel dimmer control is moved past the detent causing the interior lights to turn on.

Now that I think about it, the stock mirror has a three pin connector. One is ground, one is +12VDC and perhaps the third one is a redundant ground that bypasses the internal map light switches (unused in the Reatta application) that would serve this purpose. I haven't looked that closely at the stock mirror wiring, so cannot say if this is the case. If it is, then one wire needs to be fed along the front edge of the headliner, down the A-pillar and then under the dash and tied to the interior courtesy lamps switched ground.

KDirk

[D-a-n-i-e-l]

Is there a way to rewire the map lights to come on automatically when the doors are opened on the 1990 convertible? This would really be nice as there is not very much light inside when the doors are opened at night. Of course, it would also be great if this did not cut out the switches on the mirror so they could be used individually when needed.

Thanks in advance!

Yes it can be done, but a much simpler solution would be to change the dome light and others to LED. Lucus had done this on his and it is easily three times brighter than my interior lights.

[wws944]

The stock mirror does have a third wire for this purpose. But for some unknown reason, Buick decided not to run the extra wire. I couldn't begin to speculate why...

It seems like a simple mod. One thing to watch out for: The courtesy lights are wired such that they are always 'hot' on one side. The 'ground' side is completed by routing through a relay that is controlled by the BCM. This is backwards from what the mirror expects. You would want to apply +12v to pin C when the courtesy light is wanted. So an extra relay is probably needed. Look carefully at the wiring diagrams on pages 114-2, 114-3, and 114-6 of the FSM.

If one upgrades to the Roadmaster compass mirror, I think the courtesy light connection needs to be grounded. This is exactly what would be needed in the Reatta to avoid the extra relay... See: http://forums.aaca.org/f116/compass-rearview-install-instructions-258705.html

As an aside, I have a spare map light mirror that is almost identical to the Reatta one. Made by Donnelly, same button style, same light style, same connector, etc. Interestingly, the B and C wires are reversed from the one in the Reatta. Have had it long enough that I don't remember what kind of car it came out of - though it was definitely early '90s GM.

[NCReatta]

Is there a way to rewire the map lights to come on automatically when the doors are opened on the 1990 convertible? This would really be nice as there is not very much light inside when the doors are opened at night. Of course, it would also be great if this did not cut out the switches on the mirror so they could be used individually when needed.

Thanks in advance!

Terry,

I've been wanting to try this same thing. If I can get ahold of a Roadmaster mirror, I'll give it a shot. If it works, you can come up and we can give yours a shot as well!

[wws944]

...

If one upgrades to the Roadmaster compass mirror, I think the courtesy light connection needs to be grounded. This is exactly what would be needed in the Reatta to avoid the extra relay... See: http://forums.aaca.org/f116/compass-rearview-install-instructions-258705.html

Thinking about this a bit more, and I know it is slightly off-topic for the stock mirror, but the fourth wire on a Roadmaster mirror would also need to be hooked up 'always hot'. Otherwise the courtesy lights would only work when the car is running.

[padgett]

If you get the Roadmaster light, be sure to get the mating connector and a few inches of wire also, it make the mod much easier.