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Pages: 1

Help! Fog Lights Refuse to Work

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Posted by: skymasteres

I bought a set of Marchal 750 fog lights for my Mark VII, hooked them
up, and nothing, they do not work!

I took the lamps apart and the bulbs are fine, the plugs and wireing harness
are in excelent condition, and the fog lamp switch lights up when I switch it
on, but the fog lights themselves do not light up.

Has anyone seen this happen before? I looked in the owners manual and could not find which fuse the fog lights are on. The shop manual for the car was likewise deviod of information on the subject, although I do have detailed instunctions for removing and replacing the lamps.

Please help....

Posted by: skymasteres

Does any one know where the fog lamp relays are?

Posted by: skymasteres

Okay here are my test results so far...

I bought a test light and;
I hooked it up and the thing lights up when I go from posative battery
to negative fog light terminal reguardless of the switch position.

When hooked up to the negative terminal the tool only lights up on the
fog light's posative side when the fog light switch is on.

I'm still lost though..

Posted by: OldSchool1

Hi.
You need to do a continuity test on the bulbs. Basically, using a multimeter, it sends a very minute amount of current through the bulb and reads it on the other end and makes your tester either beep or register infinity, meaning that there is an unbroken circut of a good bulb.

Second, you have to test if there is current going into the connector. The test light can be used for this but the alligator clamp needs to be on a good ground and the tip of the test light needs to be in the socket. If you use a multimeter, the set up is the same except you'll read an actual voltage if the socket is getting juice.

Wow. I just realized that I have zero pictures of our fog light connectors. Dude. Can you take some pictures of what you're doing for us?

Posted by: skymasteres

Quote:

Originally Posted by OldSchool1

Wow. I just realized that I have zero pictures of our fog light connectors. Dude. Can you take some pictures of what you're doing for us?

Sure, and if I get this working I'll put together a step by step of what I did.

Posted by: OldSchool1

Quote:

Originally Posted by skymasteres

Sure, and if I get this working I'll put together a step by step of what I did.

Dude is volunteering to write a tech article?!!

Cool!

Chug, Chug, Chug, Chug, Chug!!!

Posted by: skymasteres

Quote:

Originally Posted by OldSchool1

Wow. I just realized that I have zero pictures of our fog light connectors. Dude. Can you take some pictures of what you're doing for us?

Okay, OldSchool1, I have you pictures. Do you want me to email them to you?

I tried fixing the ground wire in the dash, the one that fixes the fues gague and
tach, and that didn't fix the for lights.

The only other symptom I have is that the rear defroster only stays on
intermittantly.

Any suggestions?

Posted by: OldSchool1

Quote:

Originally Posted by skymasteres

Okay, OldSchool1, I have you pictures. Do you want me to email them to you?

Yup.
I'm at john dot dancy at comcast dot net Mak sure to give me as much detail as possible and a note saying Hi I'm John Doe from LVC and here's the fog lamp pictyures and description for the tech article. It would be an understatement to say that I get a lot of Mark VII mail.

Quote:

Originally Posted by skymasteres

I tried fixing the ground wire in the dash, the one that fixes the fues gague and tach, and that didn't fix the for lights.

Different circut but hey ... one less job to do!

Quote:

Originally Posted by skymasteres

The only other symptom I have is that the rear defroster only stays on intermittantly.

Any suggestions?

Yup. Accept it.
That's standard on all Fords

The rear window defroster works by current and lots of it. To keep from draining the car or overheating wires or just plain wearing stuff out, they only stay on for a brief period of time. In my case, it's normally just long enough to make it visible out the back window.

Posted by: skymasteres

Well no, I meant that the defroster only stays on for like a half a second and
turns off. If it even turns on in the first place.

Posted by: OldSchool1

Quote:

Originally Posted by skymasteres

Well no, I meant that the defroster only stays on for like a half a second and
turns off. If it even turns on in the first place.

That's not right.

Posted by: younggunmarkvii

I had a similar problem i unpugged the switch itself then they came back on it must have reset the relay or something but they work now

Posted by: skymasteres

I ordered a EVTM Manual, so when I get that I should be able to trace down what the problem is.

Posted by: skymasteres

Okay,

I must be retarded becaue I still can't find the fog lamp relays. I checked teh bulbs and they are good.

Note:// I am working on a new MKVII now that has the same problem. (The one that has the problem originally is dead.)

Posted by: Awesund

I don't think the fog lights have a separate relay. It runs off of the headlight circuit. I've worked quite a bit with the Marchal units...

I would first check your fog light switch and then your headlight switch. If I remember, a faulty headlight switch can cause this. I liked the 3 position rocker-type headlight switch on my old '85 better. But if you have a later model dial-type, it's probably the cause. In any case, check all connections and wires related to headlight and foglight switches.