Unofficialbmw.com

[bimmer7]

exterior lights not working in any switch position, including license plate lights, but head lights, turn signals and brake lights are fine. Fuses OK, checked for ground under rear seat, looks good. Replace all bulbs with new. The book mentioned rear lights check relay in luggage compartment near power antenna: no relay found there .
Just looking for clues and advices!

[Ken Juul]

If it is just the tail and license lights that are the problem, the circuit goes throught the active check relay above the rear view mirror then the Rear light Check relay behind the trim panel left hand side of the trunk. Either of those can cause the problem.

The side markers go directly from the switch. Pin 8 powers the front LH lights, pin 5 powers the RH side. Pin 1 powers the rear side markers. Switch power is on pin 7.

Since the headlights work, there is power at the switch. My guess is the switch is failing.

[bimmer7]

Thanks for the prompt reply Ken!

As you mentioned "switch", I assume that's a pull out 3-position light switch on the Instrument Cluster near the driver door. Correct me if I'm wrong

And the Active Check Control above the rear mirror indicates time-to-time rear lights burned out bulb...

No Rear light Check relay behind the trim panel left hand side of the trunk found in my convertible. Bunch of wires from all lights traced and goes inside and under rear seat.

My plan is to take the switch out and clean it thoroughly.
I will post the results upon that.

Thanks again!

[Ken Juul]

Yes the main light switch on the dash. Before you pull the switch, pull the connector off it and connect the pins....pin 7 to 1 then 5 then 8. if the lights come on, switch is the problem, if not keep looking.

[bimmer7]

Hi Ken,
Thanks for the clue! There is no #1 pin socket in that switch connector, empty nest. But I'm still checking... takes long time to get that switch in hand
Regards,

[Ken Juul]

ok maybe the numbers are off on the diag. Wire colors is the next way.

Fuse 22 powers the left side F marker & left tail. Gy/bk wire into the switch, gy/yl wire out of swtch to lights.

Fuse 23 powers the rest. gy/gn into the switch, gy/wt out supplies right f marker, right tail light, license check circuit. gy/rd supplies license lights, and both rear markers.

[bimmer7]

Hi Ken,
No matter pin numbers, (latest year E30 comes with many extras inside that dash board) wires are traced by colors and switch connector tested as you mentioned. No light coming up. So switch is OK.
Looks like the next step is "rear lights check relay". It has to be found and checked. Bentley service manual covers models up to 1990, not mine for this particular matter...

Behind that trim and guts I took out to reach to the switch, few relays found located on a vertical panel. And above relays is orange large AirBag electronic unit. Just curious how to define the Rear Lights Check Relay? any part number in particular?

I am suspicious all those relays discovered and other units could be covered in E36 service manual...

Ken, I do appreciate your time and help by the way!

[Ken Juul]

something is not making sense. The marker lights go straight from the switch to the lights, no relays. Did you check for 12v on the input wires, gy/bk and gy/gn? Have you checked each bulb? It is a long shot but maybe they are all burned out.

I posted a link to wiring diagrams in the fuel pump thread. Toward the bottom it has a listing of all the relays and their locations. The ones under the dash don't control the lights. The text says the rear light active check is in the trunk, the picture shows it behind/under the LH side of the rear seat.

[polyrhythmic]

I was having issues with my right front parking lights not coming on with the headlight switch, and I drove myself crazy checking all the wiring before I realized the problem was the headlight switch itself. There are a few separate exterior light circuits (they are described in detail in the Bentley) and the headlight switch activates one or more of them at once. I had a couple contacts that had corroded inside the headlight switch, it was easy to take apart and refurb, just watch out for the little springs and plastic parts that try to jump out when disassembling the switch. HTH!
_________________
Charles
1984 318i 5spd 3.91 LSD
Original UnofficialBMW BMW (Unofficially)
Pushing 300,000 and going strong

[bimmer7]

Thanks Ken and Charles!
I'll run checking cycle again, tracing wires and bulbs. Will check once more for 12v on the switch input wires, gy/bk and gy/gn.
I am positive it's something simple but takes time to nail this bug down

[gr8acclaim]

I don't know about anyone else, but on 3 out of 4 of my side marker lights, the actual light bulb socket has corrosion inside that keeps them from working. I've tested at the bulb end of the socket and have no power, and on the back of the socket and have no power, but if I get a little farther back into the wire, past the part that had potential moisture contact, then I get a good power signal. I haven't bothered to do it yet, because I've been busy, but I figure for me, all I need is to pick up a few new sockets with a little wiring on them then basically cut and paste a little with the wiring harness.

As for the back end, you might want to look at the actual connectors in the trunk where the light bulb mount cover is. Another potential corrosion point there. I've not had any problems with mine in this respect, but if I remember right, other people have had issues with leaky taillight gaskets, and if so, that could really lead to corrosion on those connectors there.

It's annoying to work your way through what appears to be a major wiring problem, only to find it's maybe a three dollar socket stopping you right at the end of the circuit.
_________________
1992 Plymouth Sundance Duster -- 263,000 miles -- RIP due to rust;
1991 BMW 325i -- 158,546 miles (plus ? miles when the odo didn't work!)