Parking and fog light gremlin

[MikeWinDC]

Hi All,

Have a bit of an electrical gremlin that I can't quite figure out. I couldn't find another thread directly related but hopefully someone has run into this before so hopefully a quick question.

Obviously when the ignition is off, the turn signal is used to turn on the parking lights on either side of the car.

When the turn signal is placed for the right signal, the right parking lamps turn on as designed.

When the turn signal is placed for the left signal, I get nothing.... unless the fog light switch is pulled to the on position. In that case the parking lights do not come on, but both fog lamps turn on. If the fog lamp switch is pulled on when the right parking lamps are selected the fog lamps do not come on and the parking lights still work as designed.

In all other situations the lighting works as designed with their switches turning them on or off as appropriate: turn signals, hazards, markers, high and low beams, fogs, reverse, etc.

Any idea how only the left parking lamps are connected to the fog lights and how to correct this issue?

Thanks for any hints, suggestions or knowledge.

[donporfi]

I think that the signal to the fog light relay is the fault you have. This problem appeared suddenly or appeared after doing some work in the car?
What happens if you have the ignition on and you use the left turn signal ?
Do the fog lights flash if you pull the fog light switch ?

[tirwin]

Do you have a wiring diagram?

My first guess is the wires on the bottom side of the fuses are swapped. I would check that the wire colors that are supposed to be on the bottom side for the fog lights and the parking lights are correct.

This also may sound like a strange question but do you have any LED lights installed in any of the exterior lights?

[MikeWinDC]

Originally Posted by donporfi

I think that the signal to the fog light relay is the fault you have. This problem appeared suddenly or appeared after doing some work in the car?
What happens if you have the ignition on and you use the left turn signal ?
Do the fog lights flash if you pull the fog light switch ?

To be honest, I do not remember when I first noticed the problem. I never use the parking lights so it was just a fluke that I noticed it at some point. The only electrical work that has been done to the car was the instillation of the Marcus Sucro relay kit over 10 years ago. I don't recall if this problem predated this work or not.

To answer your question, with the ignition on all lights work as expected. The fog lights do not flash and the turn signals work as expected.

Originally Posted by tirwin

Do you have a wiring diagram?

My first guess is the wires on the bottom side of the fuses are swapped. I would check that the wire colors that are supposed to be on the bottom side for the fog lights and the parking lights are correct.

This also may sound like a strange question but do you have any LED lights installed in any of the exterior lights?

I have the Bentley manual somewhere. That should have wiring diagrams. I'll have to check this weekend. And no LED's. All lights are incandescent automotive bulbs.

[tirwin]

I’m looking at the diagram for an SC — yours should be similar.

On the bottom of fuse 4 there is a black/grey wire that goes to the left front parking light. Do you have a test light? If you do, connect it to the battery positive terminal. Touch the probe to the top of fuse 4 (or the equivalent for you model year). Does the left parking light turn on? It should. You probably already checked for a bad bulb but it never hurts to swap in a known good working one.

The fog lights get power from fuse 1. Touch the probe to the top of fuse 1. Do the fog lights come on? They should.

If both tests work as expected the problem is between the switches and the fuses. Could be a switch or relay or something is mis-wired.

If either test fails there is a problem between the fuse and the fog or parking lights.

[gregwils]

I had a similar, but different experience with turn signals. This won't translate directly, but perhaps it may help. My turn signal issue was caused by how I had the lights connected. I managed to reverse two wires on the back of the turn signal housing, which prevented my turn signal from working.

This may yield nothing, but I would unscrew both sides - working and non-working. I would compare the two knowing that the right and left could either mirror or reverse one another. If you have anyone around you that would let you examine their setup, my guess is it would help.

[MikeWinDC]

Thanks for the information everyone! I haven't had a chance to check but I need to pick up a test light and start from there. Will report back soon with what I find.

[MikeWinDC]

Hi All,

I finally got a chance to do some poking around.

Using the test light, I did find that all fuses related to the fog lights (21) and parking lights (18 - L, 19 - R) caused a positive reaction.

So it would seem to be somewhere in between the switch and fuse.

Another data point is that I just noticed is if the headlight switch is pulled out all the way with the ignition off (*1) and left turn signal is pushed, the headlamps turn on as well (fog lights too if they are turned on).

So really the left turn parking light switch is activating the headlights and fog lights if the switches are pulled even with the ignition off.

And since the fog lights are supposed to only turn on when the head headlamp switch is pulled out to its first (*2) or second (*3), clearly something is crossed in here. As there is not a common relay, where might I start looking where the cross might be?

Thanks!

*1 - parking/tail and license plate lights would be on but no headlights
*2 - parking/tail and license plate lights with ignition on or off
*3 - all lamps including headlamps

[RSBob]

What I believe you need is a wiring diagram which shows what colored wires go to which fuses. There is also a possibility that your light switch is either bad or wired incorrectly, which the diagram might help.

Some other folks with your year might be able to set you up with one.