fog lights reversed
 

this message was originaly posted in parts thread by mistake



1986 300E fog lights don’t work with low beams on but do work with high beams on is their a most likely place to check this or just an easy way to wire them past it so they work both ways?

Thanks in advance

Marty
:confused:

someone probably wired up the pins at the headlight wrong or maybe the leads are touching insdie the headlight connector.

If you want the fog lights on while you have your low and high beams on, then you should wire them up to your taillights in the fusebox pannel. I did that on my w123, but make sure you dont overload the taillight circuit.

omegabenz


thanks for the assistance on the fogs and the previous post
I probably wont get to muck around with it till the weekend but I wil let ja know how it turns out

thanks again
marty:)

I have never been able to figure this one out.
When I looked down under the fuse box I got scared. Just too many wires packed too tight for me to feel comfortable with.
I would like to have control of the fogs by the standard pull light switch method, and I would like to have them available with both high & low beams.
They are wired correctly at the headlight where else could this be fouled up, and or is there a relay (ala the E Class owners Bible upgrade) that I can improve this system with?
TIA

bump :musicbooh (the worlds smallest violin)

I have a '82 300D rather than an '86 300E, so there is probably a difference, but I'll give you my info in case it might help.

On my '82 there is a gray/yellow/green wire that goes from the NSE terminal on the fog light portion of the light switch to fuse #11. (There is also a yellow wire connected to fuse #11. It goes to the low beam side of the right headlamp.) This gray/yellow/green wire is the power for the foglights.

On your car, someone may have hooked the gray/yellow/green wire to fuse #7 or to fuse #9. This would cause the fog lights to work on high beam only. Another clue would be if one of the high beam fuses has been changed to 16 amp, rather than 8 amp as standard.

What you need to do is check your manual to see which fuses are for low beam and connect the fog lamp wire (gray/yellow/green) to the correct end of one of them. You will also need to make sure that the fuse you connect the fog lights to has a 16 amp fuse. If you are unsure of which end of the fuse to connect to, pull the fuse, turn on the headlights and check for voltage at each end. The correct end is the one without power.

Hope this helps.

Wes

This is very informative Wes thanks for the insight.

I wonder if the "someone" (who in addition to the posters here several mechanics have suggested) who hooked up a wire wrong was an original assembler or someone installing an update?

From your post I think it might be possible then to run a bridge at the fuse box to the low beam allowing fogs with both high and low which is my ultimate goal. Is this correct?

Also I have a separate fog fuse does that change anything?

I just don't want to disturb those wires into the fuses for no good reason their probably the only neat clean and un-deteriorated ones left in the car :D

I doubt that someone hooked yours up that way at the factory. More likely it was a modification such as I have done. I took the original setup (that I described in my post) and modified it to put the fog lamps on the high beam side of the headlights. I then installed small halogen high beam units in place of the foglamps and aimed them up and slightly outward. They work only with high beam and go out when I dim the high beams. We don't get much fog here in AZ and I need "elk lights" up at Alpine in the White Mountains when we are driving at night up there.

You could "bridge" the fog light wire so that they worked with either high or low beam, but you would need to install a heavy duty diode in each of the feed wires so that you didn't accidently "back" voltage up into both circuits. Optionally, you could rig up a relay or relays to do the same thing. You could also power the fog lights from a fuse that is only hot when the ignition is on. Omegabenz suggests the taillight circuit. That sounds OK, just be sure to increase the fuse amperage for that circuit to account fo the additional current draw. That might be the simplest. If your switch is like mine, it will only stay in the out (or on) position when the headlights are on. If you wanted to use the fog lights independent of the headlights you would need a separate switch.

Cheers,
Wes

Thanks again Wes I will let you know how it turns out when I get a chance to play with it again.