Dean_Fuller

I Noticed 2 days ago the Light warning came on in my 89. With help from my son it was the driver side brake light that was faulty and so I replaced it with new....now the strange part. NOW all the lights in the driver side tail housing are gone. Parking lights, brake light and front and back side markers on driver side. The turn signal in the rear still works though. At first it sounded like a fuse but all are fine. I am cleaning grounds today but thought I would post this so I can check back later ..in case the grounds are not the cause.

I guess I should mention that the first replacement brake bulb I got at Advanced Auto Parts Per their "cross reference computer" was not the right bulb....same size but with just one connection point on bottom....correct bulb has 2. I did not notice this until after I installed it and it didn't work....it was now that the entire tail light and side markers stopped working. I later got the correct bulb at the dealer and again after install ..no light....I reinstalled the bad bulb to see if the tail light would come alive but no go. Is this just odd timing?? Or did the wrong bulb cause problems? If so how to fix?

Leon Speed

Is the front left turn signal still working?

Dean_Fuller

Yes...ALL turn signals are working fine.

Dean_Fuller

BTW..Aryan,
I lived in Wurzburg Germany for 3 years as a youngster...Germany is a beautiful country...will be back for a visit someday.

Leon Speed

I don't understand why the front left side marker would'nt work and the front left turn signal does work, they are wired together I think. trying to dissect the wire diagram, but it's not so easy...did you check all light fuses (double check to make sure you didn't miss one) and did you check if all concerning bulbs didn't blow?

My -electricly fairly uneducated- guess would be either fuses, bulbs blown, you accidently pulled something loose on the rear light fixture harnass and/or the bulb control unit is fried.

Ahh Wurzburg is a nice place. When I'm in Germany I live an hours drive from there.

Dean_Fuller

I will recheck fuses and pull the side marker bulbs...I agree this is indeed strange from what I can understand of the wiring diagram.

cold_beer839

Just for ****s and giggles, unplug the passenger side tail and move it over to the drivers side, plug it in and see what happens, and vice-versa.
The plugs are the same. That way you will will if it is a bad tail light harness.

Dean_Fuller

Swapped light housings and still nothing on the driver side....so...the light housing is fine. I'm taking the quarter panel out to clean that ground behind it. Thats all I can think it could be.

Landseer

Now, on the 84, there is a bulb compare unit, BCU.

Its a box located the vicinity of the front passenger tray / glove box.

The power for the tail lights+ rear side markers as well as the rear stoplights, passes thru that box.

I think its designed to give a dashboard signal if any such light bulbs on the back of the car are out. (Which could be a major safety consideration on an autobahn).

The ironic part is this, if an electrical component within that box itself is fried, you might loose power to those bulbs if they are good. Thats what happened to me. ( actually to previous owners, who then found ways to skin the various wires near the back of the harness and direct-feed them)

I bought a replacement used BCU. It was "less fried". It allows power to pass, but still shows a false warning for my tail lights. OK, a little bit of a win.

Am not saying its not your harness, and I've not studied the 89 at all to know if it has similarities, but keep this concept alive, even if its to troubleshoot your older cars. Wally P and others have posted on the BCU before.

medipedicman

Let me know if you determine that you need a relay. I have several used but working relays and you are welcome to one of them if it would help.

Dwayne

Hello Dean,
I had a problem similar to yours on the '84. The driver's side markers (front and rear) and driver's side front parking light were not working. I don't rember if the driver's side rear parking light was working or not. In either case, I checked the bulbs, swapped bulbs, checked fuse, swapped fuse, swapped light housings and still nothing. After removing the bulbs, I used the multi-meter to check continuity of ground lead at the light housing to body ground and it checked out - no resistance. Then I checked continuity of power lead at housing with body ground and found the problem - very small resistance. I traced this down to the hard rubber connector that comes from the light housing and plugs into the end of the lighting wiring harness. After cutting out the hard rubber connector and replacing with spade terminals with heat-shrink wrap, everything worked as it should.
If you have a multi-meter with continuity/ohm capability, might be worth a quick check to make sure you don't have any shorts.

Landseer

Good to see you back here, Dwayne.

Dwayne

THANKS.....been on the road a bit lately....

Dean_Fuller

Thanks guys...you all have given me more to look at. I'm knocking off for the night....miller time. Just getting the quarter panels out has turn into a job....I needed to remove them anyway to have recovered so this is 2 birds with one stone. I'll hit it again in the morning. Will post as I eliminate tests.

Mrmerlin

did you replace the fuses for the parking(side lights and tail lights) if not then replace them clean the contact pins for the rear light housing with a pink eraser. Check the connections inside the car for the side marker lights then are in the corners of the hatch area on the floor