Headlights won't work in cold weather

[Blakthorn]

Well the weather here is getting a bit colder day to day and I have realized that when I flick the switch for my headlights, they won't go on. Daytimes work, Highbeams work IF I hold them down, but I think the cold weather is affecting my lights because just 2 weeks ago the weather was a bit warmer and I had no problem?


Whats the problem, and how do I fix this? I have brand new sylvania silverstars as of a month and a half ago.

 

[The Shape]

Maybe condensation getting into the sockets on cold mornings?

 

[Blakthorn]

its not even just in the morning, it happened last night, i garage my car too

 

[HISSIN50]

In case it helps,
Flash-to-pass is powered via a different wire than the normal low headlights and highs. If both lows and highs are AWOL (flash to pass is not considered in this), then I would go from the headlight switch to the MF switch. The feed wire is known for backing out or burning, which could cause an intermittant issue. The wire is Red/yellow IIRC.
Do make sure that the headlight switch has power going into it.
Random thoughts........

Good luck.

 

[Blakthorn]

well your right, because when the low beam headlights don't work, "clicking" on the high beams does not work either...im not good with electrical work or wires...do you have any diagrams or suggestions...what do I need to fix this, is it wires, a harness, or something else? Whats the MF switch?

 

[HISSIN50]

MF switch = multi function switch = turn signal switch.

There is a wire that goes from the headlight switch to the MF switch (red/yell on my 88). It is only hot when the headlight switch is turned on to 'headlights'. The power is simply sent to the MF switch. At the MF switch, the lever's selection (normal or highs) is what toggles back and forth between which wires (lows or highs wiring to the lights) gets powered.

You can access the MF switch by removing the lower and upper column plastic (2 mins) and taking a look. Have torx bits on hand in case you need to unscrew the MF switch from its mount to better see the wiring.

Just make sure all the wires are seated in their pin holes (not uncommon for them to back out) and that none are burned.

You can also remove the headlight switch (10 seconds) and check the terminals in the back for continuity.

I would check with the schematic in the back of the repair manual for diagrams (what I used when chasing some issues I had).

Good luck.

 

[HISSIN50]

Oh yeah, in case you need it, a new MF switch is about 80 bucks. They are different for 87-89 IIRC (than later models) in case you grab a used one.

 

[Blakthorn]

which repair manual do you have?

 

[HISSIN50]

I used the schematics in the back of the Haynes manual.
I am not sure if it will help you much, but here is one of Tom's diagrams (site host is S+2B's):

http://www.veryuseful.com/mustang/tech/engine/images/MustangLights-Horn.gif

And autozone has some diagrams which might help too.

I used the schematic in the back of the Haynes and my meter to figure it out.

Good luck.

 

[Blakthorn]

ok, i guess its done for because today was a lot warmer and still no luck...anyway

how do I remove the upper and lower column plastic? And what size torque is needed to get the MF switch out to look?

also how do i get the headlight switch out, and is this what i need to look at when its out?

View attachment 499656

 

[Blakthorn]

ttt

 

[Blakthorn]

my man hissin, where are you

 

[HISSIN50]

Here is an article which might help with column tear-down and fastener location.

On the headlight switch, I used a tiny flatblade screwdriver to manipulate the little tab on the side of the switch. This allows the switch to come out (in about 5 seconds).

Good luck.