Car is a 1986 Volvo 245 wit M46. The lights have always been unreliable. Well after the car has sat for a year I decided to dive into it and get some reliable lights.
I first focused on the front I eventually got all the lights lights working in front. The underhood high and low beam relay was repalced. I checked the relay inside and the plug checked out good. Cleaned all the grounds. Low behold lights and directionals all worked upfront. The rear taillight would work occasionally.

So I decided to start with taillights. drivers side was working with nothing on passenger side. So I messed with them and at the same time I cleaned fuse box with new qualitiy fuses.
Still no power to the back for the brakelights. I installed a new Bulb Failure Relay nothing change. I have power at the brake pedal and thru the brake switch. Then all the sudden. I lost all lights no front or rear. The car starts and runs. I tried another BFRealy that was in good working 240. Im stumped. And hope someone can offer some help.

 

The biggest concern with your vintage car (84-86) was it contained wiring with biodegradable insulation. Over time, exposure to heat causes the insulation to degrade and cause all kinds of electrical gremlins.

You will need to trace the wiring from the fuse panel (where you have 12v) all the way to the lights. Check the wiring for shorts, etc.

 

That what I was afraid of. Im thinking that Im gonna have to pull the enterior out and replace wire harness. Would a bad ignition switch cause this problem?

 

No. Ignition switch would not cause light issues.

 

Welp, Im gonna pull the interior out of it and probably run new wiring to the back and possible in front. Does anybody have wire diagram of front lighting? I have the back figured out. Thanks

 

OMG - I cannot imagine rewiring one of those cars.

 

Its not gonna be fun but think its gonna have to happen to get rid of the wacko problems. I do have a low milage 87 model parts car but wonder if it has the same bio wire in it?

 

A quick google on it yields that they seemed to have fixed the wiring mid-year in '87.

 

deleted the BFRelay. I have front directionals and headlights. This is a start. Will work on the rear lighting tomorrow. Dont know why the BFR that was new causing problems but obviously it was.

 

Well I got it all lined out. All lights are working properly. Bypassing the BFRelay was most of it. Did have to run couple new wires to the back for tailights. Then had one short in the front which was a butcher wire job at fault.