The 97 GLT wagon that I bought 5 years ago has a bad combination. Black upholstery and no courtesy lights. I got it with about 100K on it and it now has 135K on it, with no issues. Except I never have had even a glimmer from the overhead courtesy lights, nor from the rear passenger courtesy lights above the doors.

Pulled the overhead panel and checked bulbs and switches and all are okay. Fuse in #15 slot is okay. Presently it is in the shop having axles replaced and I asked the mechanic to see if he could find the power default. He checked the overhead again and guessed it was the light relay under the fuses. I pulled that relay on my '96 T wagon to try on the '97 in his shop, but found that pulling it did NOT kill the overhead courtesy lights. I then pulled all the other relays at that location, one at a time, and none of them shut it off. So much for that experiment.

The small lights at the front of the front doors, I think they call the front door edge marker lights, DO come on when the doors are opened, indicating the door-frame switches are working. And the seat belt warning lights imbedded in the overhead console come on for 30 seconds or so when the car is started, so there is power there.

Only clue now to go on is a brief passage in the Haynes Manual:
'The courtesy light micro switches are incorporated in the door lock assembly together with the central locking motor. Replace entails unsoldering a number of small contacts and soldering in the new wires. As there is a risk of damage to the central locking motor and the lock itself, this work should be entrusted to a Volvo dealer."

Is this a lead worth chasing or are there other avenues to pursue. Indeed, on a working system, the lights come on inside when the vehicle is unlocked, and stay on for 30 seconds, same as when leaving. I could see a microswitch failure there preventing lights on when the car is unlocked, but one would think that there still would be power to the overhead courtesy light buttons. Wiring diagrams in the consumer manuals are chassis wiring and too skimpy to help.

The micro switch in the door lock also controls the door jam light, so it is OK. If manual operation of the overhead light switches also does not work, I suggest looking for a loose ground wire.

Thanks, Klaus. Scratching my head as to how to go about tracing down a faulty ground. I don't think the car has ever been worked on mechanically under the hood in a serious way, so I would not know how to start.

By the time I got the 97 GLT out of the shop for the axle replacement, my mechanic had just discovered via an on-line wiring diagram, that there is a third level of relays under the fuse cover (fuses being the first layer, lighting and other relays being the second level--visible after the cover is removed, and third layer being what is revealed when the fuse block is pulled up).

No relays visible when you peer at an angle under the fuses, but the wire bundles are too thick to see past them. The fuse block appears to be held in with three torx screws. I hesitate to dive in because a) I don't know what relay might be feeding the courtesy lights and b) on the top of the fuse cover in three languages is written the following: "NB! When lifting the junction box, first remove the contact unit from alarm relay (pos 210.211)" What is meant by that? Where is the alarm relay and what is a "contact unit"? And "junction box" I presume refers to the fuse block. Or is it something else?

Thanks, Klaus. I thought it had passed the test locking test, but I guess it flunked it. Will try the one from the '96.
But, again, do you know meaning of the warning on the plastic fuse block cover: "NB! When lifting the junction box, first remove the contact unit from alarm relay (pos 210.211) ?

When 'lifting the junction box' means the box that holds the relays, not the fuses. You do not need to lift the junction box. The 210/211 relays are what they are referencing.

The top layer of the fuse block comes off with 4 torx screws. Just loosen the 4 screws, they do not have to be totally withdrawn. Under this you will find all of the pertinent relays.

I sent you an Email with a PDF.

Try something for me. Lock the car and let it sit for at least 30 seconds. Then unlock the driver's door only. Do not open the door. If after 30 seconds, the door does not lock again like it is supposed to, the relay #11 on the chart is bad.

Klaus, thanks for the PDF. Great resource. I tried your 30 second tests on the lock, and the key locked it again normally after the last 30 second wait. So does that eliminate the door light delay relay #11, or could that still be the culprit?

The car door should have locked all by itself after 30 seconds in the unlock mode. Try the relay from your 1996.


BTW, pick&pull junk yards are full of relays.