Vistabrat72

Hello to the forum. From a fellow member I was able to get the map light that goes under the dash, just above the radio to the slight right of it, fitting a 1972 Cutlass/Vista Cruiser model. There are three spade connectors on it, the one lone positive was easy enough to figure out (I hope) going to a constant 'hot' orange wire with a female spade on the end. On the other side of the light assembly there are two 'grounds' I figure, one could be plumbed into a still yet to be found white wire, probably part of the foot well light circuit. But to use just the map light alone, using the switch on it, without lighting the other courtesy lights in the car, does anybody know the secret to this one. Looking at the way the switch works, it looks like if I merely ground the second spade lead on the ground side when I turn the switch on, all the other lights will light up too. The service manual is a little vague in the wiring diagram, has anybody been able to light up the path down this trail in the past? Any help would be appreciated, thanks in advance, regards, Howie.

matt69olds

I would think you could use a diode in-line with the white wire to prevent the map light from lighting all the interior lights.

Vistabrat72

Oh my Matt! That answer was right under my nose, I so should have thought of this, and I have a slew of diodes kicking around! Thanks so much, I will wire the diode into the wire coming from the foot well lamps to keep the current from flowing back into them from the switch on the dash! Again, many many thanks! Howie.

matt69olds

After thinking about this for a while, the diode is the best solution I can come up with. I'm curious how the factory did it, anybody in readerland have any info?

Vistabrat72

Yes, it would be nice to see just how the engineers in Lansing went about this method. We have to remember, the Lansing crew had a pretty wide open budget to come up with some of the nice interiors and features seen on so many Oldsmobiles, perhaps they were able to do the diode thing themselves.

MDchanic

I have not had that specific car, but, in general, for cars in that range, flipping the map light switch turned on the map light and the two front under-dash courtesy lights.

- Eric

dfire25

I'm not sure if this helps, but the switch operates like this. "When you open the door the light comes on" lol old Chicago Bears fans will enjoy that! Anyway, when you use the switch on the light, it turns the light on and the floor corticy lights. So that's why the two ground leads and the one positive lead. It's kind of a dual purpose light.

dfire25

Oops! Mdchanic posted just before I did.

Vistabrat72

Hello to the forum. Well folks, I got the light to work, and thanks to the 'reminder' once again from Matt to use the diode thingy. I thought I had diodes kicking around, as usual, when you need something it is always elusive, even with a bit of order in place. Too many things in order I guess. Oh well, so I used an old diode trio I had from a GM alternator, and if you note the photo with the red oval for orientation of direction, the project worked. All is now soldered and taped up, not one O/E wire in the harness was cut on the car either. As you can see in the mock setup, the white wire went to the white/black stripe on the foot well lamp, the orange is hooked to the lone positive side of the under dash lamp, and the black wire clutched in my hand is now grounded to chassis. When the doors open, the under dash lamp comes on with the other courtesy lamps. With the doors closed, when I flick the switch on the under dash lamp, only it comes on as hoped! Obviously the new lamp is protected by a fuse too. Enclosed are pictures of the project and final results. Thanks again to those who helped. The question remains, how did Oldsmobile pull this one off??!! Howie.

LNCTIME

Awesome pics and explaination. I have one not working, and this will help guide me. THANK YOU!