Hello,
firstwall, I want to thanks people for the help they give to me on this forum.

I've now another problems on my aerostar. I will make two topics fore mere clarity.

My first pb is ont the headlights :
When I turn the lamp on (first position of the switch), the small lamps lights.
When I go to the second position, The headlamps give no lights. But I could always made optical hightbeam.

I've check the harness who goes to the switch, and I've current on it.

I think that I have a problem on the hight beam switch (this one who is actuated by the same lever of the turning signal), but I'm not sure.

If somebody could help me....

I apologize if some technical terms are not correct, but I am from france

 

The switch itself is probably burned out. Happens a lot, they really can't handle the current of the headlights.

 

If the switch fixes it, help us out by doing and autopsy on the old one. I'd like to know if the contacts are badly burned or not. Pics would be great!
Good luck on the repair. I think it's the switch too.

 

First guess multi function switch, and be sure to inspect the connectors for signs of heat.

 

The switch you think is burnout is the one located near the steering wheel ?
Do I need to change any relay ?
Do someone have the ford ref in order I try to find it in France ?
Thanks for the help

Phil

 

You need to replace the headlight switch on the dash. There is no relay, the full current runs through that switch, which causes it to fry and fail.

I believe it is a common style switch found in most fords of that era of Ford trucks and some cars so it should not be that hard to find either from the dealership or aftermarket.

 

The headlight switch (in the dash upper left) is a known weak area. They burn up with alarming ease. The headlight switch connector also melts.

You have voltage at the headlight switch. With the switch pulled out entirely (headlights ON), do you have voltage at the Red/Yellow wire?

(click on image for larger)


If you look at this HL wiring diagram (sorry for the poor quality), you can see that the MF switch (dimmer stalk) powers the headlights via two separate circuits, only one of which is through the HL switch on the dash. What this means is that you may be able to activate the headlights by pulling the MF switch lever towards you (and holding it: "flash to pass" mode), powering the HLs via fuse 12, but if the HL switch in the dash has failed, you will not have normal function of the HLs.




If you do not have voltage at the Red/Yellow wire of the headlight switch, with the switch ON (**** pulled out entirely), you will need to replace it, and the switch's connector should also be inspected for overheating.

 

Hi,
Thanks for the advises.
Unfortunately, my headlight switch does'nt look like your pictures. I think it is because my Aerostar is a 1991 model, with electronic dashboard.
Anyway I've test the red yellow wire (beetween this wire and the black one (G), and my voltmeter indicate 12V.
So, I think, but not sure that the pb may be on the turn signal/hight beam switch ?
And I've see that there is a hightlight relay alson. Perhaps it is this relay whitch is dead. But I don't know where it is and how I could test it.
If not, what could I test ?
Thanks for any advise.
Phil

 

You would have saved a lot of time if you had stated the year of your Aero at the beginning. Edit your Signature on this board to include that info.

The HL switch is different 1986-1991. I do not have time right now to dig out the wiring diagram for the earlier HL switch.

Armed with a wiring diagram, you can diagnose using a step-by-step procedure. Without a diagram, you have to know a lot more about what you're doing, and have to make educated guesses. Naturally, the former method is recommended.

The early HL switch is not as prone to fail as the later one, but I have had one bad.