I got a 1990 240 wagon with the driver's side tail light out. All other lights, including driver's side brakes, are fine. Tried swapping the bulb holder, new bulb, etc. Tested for power at the red wire going into the assembly...nothing. checked a little further up the wire... nothing.

Not sure what the next step would be. Looked at the mess of wires going into the fuse box, but there was nothing obvious that jumped out. I'm not even sure if the tail lights feed out of the fuse box.

Any tips would be appreciated.

 

The parking lights are fused left and right - the two bottom fuses.

If the left front parking light works the fuse is ok (unless someone rigged something)

The rear parking lights, the brake lights (all 3), and the low beam headlamp wiring goes through the bulb out relay - I'm guessing the bulb out light is on. The bulb out relays fail - big round relay under the drivers side of the dash - they usually fail on the brake light circuit, not the parking lights. But you could trace the wire on the taillamp back to the bulb out relay. Sorry, I don't have a wiring diagram to verify the red wire is the correct one.

 

lets see, 1990 240 wagon USA model,

left tail light...
red - parking light
yellow-grey - brake light
black - reverse light
white - rear fog lamp
black - ground


right tail light...
brown - parking light
yellow - brake light
black - reverse light
(white - rear fog lamp on RHD cars only)
black - ground

all light circuits are hot (+12V) if hte light is supposed to be on, or open circuit otherwise. all lights negative side goes to the common taillight ground on that side.

if *ALL* the left rear lights are out, its most likely the ground on that side. on a wagon, the tail lights are grounded to a screw thats below the outer carpet panels on the trunk floor, and just forward of the outer rear corners of the hatch.

 

Ahhhh. Think I got it. Parking light = taillight. Never heard that one, I was assuming parking was referring to the yellow fog light or something. That fuse towards the bottom is blown, so that it's.. I think.

Thanks!!!

 

well, the tail light is the whole assembly on the tail of the car. the parking lights are the rear lights that come on with the first position on the headlight switch, along with the front corner lights.

fuses only blow when there's a short to ground on that circuit, so if its blown, odds are it will blow again.

 

It's working now. I'll keep my eye on it.

May have blown the fuse fussing with the bulb holder originally. I always have trouble with those things. kinda hate 'em.

I have yet to see the bulb failure light come on in this car. I seem to recall in my old 740/940s that would light up when anything went out. Maybe that relay is something to look at if it goes again.

thanks again.

 

The black wire at the bulb out relay was commonly cut to eliminate the bulb out light - because people could not figure out what was wrong. It does work - if you use matching bulbs. That is the same exact brake light bulbs, same rear parking light bulbs, same low beam bulbs. The system compares the current that each pair of bulbs uses with a simple technology - a magnetic reed switch is tripped (lighting the bulb out light) if one bulb uses more current than the other.

And notice the two parking light fuses - one powers the tag lamps also, and the other something else (can't remember). Meaning if the cargo door hinge wiring going to the tag lamps breaks - and grounds out it will blow a fuse for whatever side parking lamps it's connected to. Maybe only when you open or close the cargo door.

 

Or the wiring in the cargo door hinges is broken and grounds out blowing the fuse when the cargo door is opened with the lights on - check for broken wires in the hinges

If the bulb out light did not come on - someone has probably cut the black wire from the relay, because they were tired of seeing the warning and couldn't figure out why it was on