Hey all, I am trying to work through some sort of electrical issue on my 1991 240 Station Wagon. Sorry for the long post, trying to be very detailed as I’m losing my mind!

Almost all of the lights on the rear end do not work. The following lights are out:


My main concern so far has been the brake lights. I’ve gone through all the troubleshooting steps I could find and think of and am stumped. I have gone through the following with my multimeter:

I have tried tracing the wires to the back to the taillights and the parts I can see are nearly pristine - no fraying or damage (except at the hinge of the tailgate). The contacts on the light housing don’t seem dirty and I tried reseating the connectors with no luck.

The manual says there is a connector somewhere between the BFR and taillight housing, but I haven’t gotten a chance to pull the entire car apart to find it.

If I were to assume the wiring was all good, is there anything else that could be causing this? Would the frayed wires at the tailgate hinge affect the lights in the housing? Anything else or steps I should take?

Also, what are the top red lights in the rear fixtures used for? They have violet wires running to them. These also don’t work and I can’t figure out what they are for.

Any help is much appreciated!

 

Andrew, it sounds like you have done a thorough job of attempted diagnosis. In answer to your last question first, the rear fog light is in the left upper position. It is controlled by the rocker switch on your dashboard just above the headlight switch. It may be fully functional.
Inside the tailight module on each side you may not have noticed that each bulb is held in place over contacts by a plastic bulb holder that has a matching set of contacts. This whole assembly is made out of plastic. The bulbs generate a good amount of heat themselves when lit, and more heat can result if the bulb holder contact surfaces are poor. This heat can get especially bad if the car has both the taillights and the brake lights on at the same time. Think stop-and -go traffic here at night. In addition, the bulbs that fit into this holder are available in multiple wattages and if a too-high wattage bulb is selected sometime in the car's previous history can result in too much heat. This heat buildup in the confined space of the taillamp causes the black plastic backing that the contacts are attached to to actually melt, giving even more resistance to electrical flow, which causes more heat and even more melting.
So take each bulb and holder out and carefully inspect the assembly. If you see the slumping of melted plastic you can try to bend the contacts back into place or solder a nubbin onto a contact to give it more reach. Or better yet, replace the assembly itself. They are available new aftermarket, or better yet NOS from Volvo.
What a few of us 245 owners have done is give up the rear fog and change the wiring to use the top socket for tail or brake lights. This spreads out the heat load and prevents this melting from happening again.

 

Sambar - thank you for the thoughtful response! I will check the plastic around the fixture to see if there is evidence of this and consider switching the wires to the top bulbs.

One thing I forgot to mention is that there is no power reading at the ends of the yellow brake light wires when the brake light is engaged.

I also tried flipping the running lamp and brake light wires. Curiously, the brake light does not light up when the known hot running lamp wire is touched to the brake light contact. Is this because it is too low of a wattage to turn it on? There is also a slight delay in the running lamp bulb lighting up after putting the running lamp wire to the running lamp contact.

Going to continue diagnosing today.

 

Have you disconnected the connector at the light housing and rung out each wire with switch on and pin to fuse. If you get 12V at the connector then the tail light housing wiring or bulb holders are bad. If no 12V then you have a major wiring issue.

 

Well I figured it out. This was actually my girlfriend’s car and she told me she had changed all the bulbs and checked all the fuses. I rechecked today and turns out she did not completely - so this solved a couple issues.

The rest of the non functioning lights were fixed by taking out the fixtures and scrubbing the contacts with a wire brush and contact cleaner. Then re-bending them to ensure good contact between the surfaces. I think I’ll just replace the housings as both have cracks and water is able to get in, soiling the contacts.

In short, it was a combination of several problems. Thanks for the ideas and help!

 

if you put some dielectric grease on those contacts it helps a lot.

 

+1 on that