Okay, I've searched the forums and haven't quite found what I'm looking for.

I have a 1990 DL 240. I noticed the brake light fuse was blown. I replaced it with another of the same type (white 8 (P) fuse) and it blew as soon as I hit the brakes. I replaced with a higher amperage fuse (red...don't remember exactly the amps), and when the brakes were hit, it got really hot and smoked a bit. Wiring to the lights themselves looks okay, but I haven't gone too much farther then that. Can someone point me where to look next to diagnose the issue?

Thanks!

 

it sounds like you have a short somewhere. Just a thought has anyone ever added a trailer? often people add trailers and muck with the wiring not knowing what they are doing. I'd take the fuse out, take both bulbs out and then see if you have some amperage across the fuse when you step on the brakes. If you do , then what's drawing the current?

first look in the trunk to see if the wiring seems to be factory or if someone messed with it. maybe someone removed panels and had stuff knocking around the trunk and that could damage or short something.

there is some electronics that compare the current draw of both and if it is uneven it will make the bulb failure light come on.

have the covers been removed and left off where you change the bulbs in the trunk? maybe something touched the circuit boards and shorted them somehow?

look around the trunk area, maybe there is a connector where you could unplug the tail lights, and then separate your troubleshooting at that point?

if you want them to draw less amperage you can put in LED bulbs. that's a good thing to do if you do pull a trailer as it takes some current off the system. you obviously have a larger issue there though so it isn't a solution.

make sure you have the correct bulbs. Its more important in this application, and if you put the bulbs in backwards or put the wrong ones in you might melt the lenses.

I wouldn't go to a larger fuse or try jumping it, you might fry the wiring. You shouldn't need a larger fuse than the stock one.

the traces on the circuit board for the rear lights were a horrible idea, they always have poor contacts and go intermittent. the newer the volvo, the cheaper they got witht the little bit of metal it would have taken to make them reliable..
I got to the point where i just removed those silly circuit boards and instead installed normal sockets. What was volvo thinking? the rest of the car isn't made like crap but that thing sure is.

If you are changing bulbs or troubleshooting , take a flashlight and have a look at the traces where the springy things on the weird volvo factory bulb holders make contact. I think your car wil have a flimsy circuit board made out of a piece of plastic. it's real garbage but you can probably replace the factory part if you want to. it's kind of hard to fix them as there isn't much to solder to.


a bit more on the trailer issue.. north american cars usually use a three wire system. the signals are each one wire and brakes send power to both of the bright filaments, the other wire is tail lights and white is ground - to chassis.
Im sure you have seen the "normal" little flat plugs on trailers with 4 prongs, the white has the connectors the other way from the three with power.

but Volvo did it differently. on a volvo you have brake lights , right and left signals, tail lights and ground , that's 5 wires..

so to fix that you can add a little controller that converts a four wire system into a three wire system ( ignoring ground wire) so you can pull a trailer with that common standard kind of trailer plug..

now it's of course possible to re-wire your trailer so it can accept the volvo wiring system but then you need separate brake light bulbs and no one will want to borrow your trailer. wiring the trailer to fit he car vcan save you having to buy the wiring converter gizmo.

what I did was glue two trailer plugs together,, If you want to spend more money you can get other kinds of trailer plugs , some might have a wire to charge a battery in the trailer... I made my own and made it work with the volvo or with my ford van by figuring it out and I use an adapter that I made up. I needed to add extra lights so the trailer can work like the volvo , in other words the brake light filaments are not the same wire as the signal light filaments.

anyway long story short you could likely find someone tried to pull a trailer and started hacking the wiring and got confused, or you might find one of these wiring converter things in the trunk area.

If you have no hitch , then this may not be the case. I dont' think people often install hitches and then remove them. there might have been a trailer package option from the dealer.. anyway you can see why people go to pull a trailer and then think ok I just have to hook up the trailer lights and because a volvo is wired differently they get in over their head. If that's the case youll probably find wires just twisted together and black taped and not soldered, and that sort of mickey mouse wiring might cause all kinds of issues.

I think the wires will be running up above the headliner along the roof on the drivers side and come out at the left side of the trunk around the wheel well . its unlikely to be damaged there. more likely damaged inside the trunk area. If you burn up those wires by jumping fuses then you might be in for a task of pulling new wire in.