Today I put a map light out of a 1968 98 into my 68 Delmont 88. Insulation went in without any problems. however when I wired the light up it only works when the door is opened. It will not work when you turn it on with the switch on the map light nor when you turn the light on with the light switch itself. My trusted service manual shows that it has a grounding wire which I also grounded but not to where it shows in the manual. Could this be the source of my problems or is the switch bad on that side of the light? I do not have any voltage testers as of yet but I see the need coming soon.

 

Sounds like you may have attached the wiring backward. Try swapping the wire connections and see if that doesn't fix the problem.

 

The connector will only go one way. It will not connect any other way. This car DID NOT come with a map light just a delete plate covering the opening. It did however have the wiring harness under the dash. The light I took out of the 98 has a grey and orange wire and the plug in harness under my dash is the same color, one of the prongs goes up and down and the other prong goes side to side, no way to plug in backwards. ( I think )

 

I'm not up on this particular model, but most GM cars from this era had the ground switched. By that I mean the orange wire is "Hot" all the time. And the door switch completes the circuit by "grounding" the gray wire. So your first thought about not having a good ground is likely the problem. Or a bad switch.

Don

 

What happens with the door closed and ignition key in the on position. Perhaps when installed that light works as a courtesy light as well so long as the ignition switch is in an off position.

 

Don is right about orange being "hot" all the time and grey being the ground. You are right about the connector being "Murphy" proof, only one way it can go. I have a wiring diagram for the 1969 car which includes Delta and 98 models so I wouldn't think that there would be a difference in the way the grounds are switched (functionality the same). However, by your description of the problem it sounds like the ground is only switched by the door switches and not by the courtesy/light multifunction switch on the dash or the switch at the light itself. I think I have a solution on how to fix the problem. If you have an Ohm-meter, Check you map light switch and be sure it is closing when you activate it. If it is, make sure that one side is grounded, it could be that as installed on a 98 model there was metal to ground and on your Delta is is only plastic or the ground is interrupted.

 

G.P.S. units have both maps and lights.

 

I checked my wiring diagram now that I am home. The grey (actually, it was originally white according to the drawing but I agree, it looks grey) wire from the lamp should be joined electrically to the switch which has only that one wire to it, the other side of the switch is shown as ground which means it is mounted in metal, grounded to the chassis, to the battery that way. It works the same way as the door jamb switches do (and is in fact in parrallel with them so that any one of them should activate the map light as well as the courtesy lights). Don't see where it is activated by the main headlamp/dimmer switch though. The orange wire is always hot, as are the other orange wires to the other lamps.

 

Well here's how it all played out. First thanks to everyone who has replyed to this post. Thanks for all the tips and advice. So this afternood I get a meter from a friend of mine in order to test my map light switch. Orange IS hot at all times. we also tested the ground, it was also good. As I played with the map light switch the light flickered. I said to myself "Self it's not making good contact!" So with a small file I cleanded up the contacts and with the needle nose I tweaked the contacts together and BINGO I CAN SEE THE LIGHT!!! It works off the switch and also when the doors are opened!! Now who needs a G.P.S unit when a fold out map and WORKING map light will do the same thing!! I think we can put this one to bed.

 

Excellent! I am glad you got it going. A Volt-Ohmeter is not that much and an invaluable tool in my opinion. I bet those contacts just got a glaze over of corrosion over time, seen it happen before. Nice.