I hope someone has a clue on how to check my problem. My '93 940 Wagon runs great but last week the bulb failure light came on and it's been an on and off problem with my right rear brake light. Like a lot of old Volvos 20 years of hitting the brakes heated up and melted the plastic mounting plate where the bulb holders screw(twist) in. I glued a temporary fix but the bulb falls out when I hit a bump and the failure light comes on. All other electrical systems work perfectly. I picked up a used tail light assembly and popped it in and the right side lights all work as they should. But the left side(drivers) rear turn signal now is not. First thing I noticed is the failure light wasn't coming on when I left bulbs out so I got another one and now it works properly when there's a bad bulb. But the left side turn signal gives the classic super fast on and off clicking which tells you it's a bad bulb. I switched left and right bulbs and it's not the bulb(including the front left turn signal). So I connected my test light to the connector going to that bulb and there's no current when it's clicking. So somewhere along that circuit there's a break. Yet, oddly, before I changed the right side lens assembly it was working fine. I've looked up some of the online wiring diagrams and I can't find any that show the turn signal circuit. Any help? Thanks

UPDATE: a got a Chiltons and they're pretty useless. It shows a seperate circuit between the turn signal switch and the tail light. But that's not accurate. There's a relay between the two. Any ideas?

 

so the back bulb is not blinking, right ?

flashers:
https://photos.smugmug.com/Misc/Volv...PxSs5tq-X2.jpg

parking lights:
https://photos.smugmug.com/Misc/Volv...N9kbzTL-X2.jpg

brake lights:
https://photos.smugmug.com/Misc/Volv...BPmNH4R-X2.jpg

this is direct from the 1993 940 volvo wiring green book.

 

on those diagrams, 2/36 is the flasher relay, 3/5 is the turn signal switch, 3/6 the E-flasher switch, 7/75 is the bulb failure sensor, 2/37 is the headlight relay, 3/2 the headlight switch. 15/1 and 15/2 are positive terminals, 31/*** are grounds.

 

Hey Pierce, thanks for jumping in. Yes, the rear bulb is not flashing, the front is. I'm assuming that 5/1 is the instrument cluster lights and it looks like a direct connection from there to the tail light. And since the left turn signal on the instruments is flashing(but very fast), then it has to be a break between the two?

And I just checked the hazard light and again both front lights and the right, rear light work but the left, rear doesn't. And both left and right dash lights are flashing. Somehow there's no power getting to that left rear light. Finding that break has to be like finding a needle in a haystack. Any ideas on where any junctions/connectors are that I can test?

 

yeah, 5/1 is the instrument panel.

connector C1 is '53 pin instrument panel - door sill harness', and left rear is the green wire on pin 7. right rear is the blue-green wire on pin 8.

connector C2 is the '53 pin instrument panel - left wheel housing harness', left is pin 13, also green.

connector C3 is '53 pin instrumnet panel - right wheel housing harness'

 

Well, I'll start the hunt. But here's something that's strange. The wire coming off this left, rear light is not green. It's black and there's 2 wires(both black) coming off that bulb.

 

the wires from the left tail light should go along the left side door sills after going over the rear wheel hump. if you remove the rear side floor panels, door sills and back seat and lift the carpets up a bit, you should see the bundle. its possible someone spliced new wire on, its also possible volvo randomly used the wrong color wire during assembly.

 

I'll check it out thanks.

 

you should be able to see that C1 connector up under the drivers side dash. I think its right near the drivers door hinges about halfway up. they are big block connectors, I don't suggest you try to unplug it as the insertion force is very high, just probe the connections from the outside.

 

Good tip

 

those 53 pin block connectors, one end has 5 rows of 5 pins each, the other end has 7 rows of 4 pins each. on C1, pins 7 and 8 are in the middle of the 2nd row from the big end.

 

Well, problem fixed. Chaffing under the door sill broke the wire. Luckily I didn't have to do any deeper digging. Thanks Pierce for your help and I'll save those diagrams for future use.