1991 Volvo 240 sedan - problem with Fuse #7
 

Hi all,

I have a '91 240 sedan that has had recent problems with a new left tail light that keeps going out. Bulb is not blown. Problem seems like it must be electrical in some way. Similar to a couple of posts I've seen from a few years ago, yesterday my gear shift locked up and the button could not be pushed to move out of PARK. Once removing the gearshift cover, my mechanic (a Volvo specialist) noticed an odd yellow emergency release switch that he said he'd never seen before. (See attached photo) Upon further investigation, he then noticed that Fuse #7 was blown... which also controls the tail lights with which I have had several probs. He also noticed that the white, 3 way socket appeared to me slightly melted in the center and that the circuit sheet (for lack of proper terminology) appear out of shape.

Does anyone have any idea 1. whether the gearshift problem is because of a problem with the fuse or 2. whether the fuse has a problem because of the tail light problem... which has now affected the gear shift... or any other scenario?

fuse 7 is the brake light circuit, and afaik goes nowhere else the parking brake interlock relay...

looking at my greenbook wiring diagrams..

power from battery goes to "positive terminal" and red wire from positive terminal goes to fuses 6-7-8-9-10 (so these fuses are ALWAYS hot).

fuse 7 goes to brake light switch via green-red wire. blue-red wire goes from switch to brake lights /and/ pin 85 of the shift lock solenoid. pin 86 of the solenoid is blue-yellow wire to

pink wire to .... arrrgh, this diagram is drawn wrong, it doesn't make sense.

anyways, the shift lock relay is on the right side of the center console, left of the passenger footwell. it probably has yellow, pink, blue-yellow, and blue-red wires to it. the shift-lock solenoid under the shift lever has yellow and black (ground) wires. if that yellow wire was pinched to ground, then for sure, it would trigger a short in the brake light circuit and blow fuse 7, knocking out your turn signals..

Thank you for your reply. I have had no problems with the turn signals. Only problems seem to be intermittant with brake lights. My interest is finding out "which came first": some problem with the fuse/circuit that is causing problems with gearshift lock and brake lights, or if the initial problem might be a short in the brake light that is triggering a short in the fuse, which in turn is causing the gear shift problem, etc.....

if fuse 7 blows, there's no power for the brake lights or interlock relay.

a short to ground anywhere in the brake or interlock circuit would cause that fuse to blow. most typically, this happens when insulation fails and the conductor comes in contact with metal parts.

I realize that. I am wondering if a bad tail light assembly might/could be the cause of a short. It is a new assembly - replaced after an accident in July. We have noticed that one of the sockets has melted inside and that the "circuit sheet" (for lack of appropriate terminology) doesn't seem to be sitting corrently in the area of that melted socket. Or is it more likely something else causing the problem?

yeah, that sho nuff sounds like a potential short to me... anything that lets the current make a short circuit from the power to ground without going through the intended load (the lamp bulb).