HELP! Headlight switch failure

[pooleo8]

Today I decided to tackle the failing odometer. It was a simple fix. Just a quick re-solder of the pin on the board. After putting the dash back together, I notice no dash lights...?

Then I smell smoke! It was coming from the headlight switch assembly. the PO had broke the outer cover, so I was able to unplug the switch and pulled the cover off, to discover the transistor of regulator (unsure) was HOT! Way to hot to touch and I burnt my thumb. I jiggled it around a lil bit and it came right out from the solder joint. That is how hot it got. The transistor has heat marks on it and the side are buldged. Any ideas on what the source of the problem is? Anyone have a wiring diagram of the switch and cluster?

Thanks for any help.

 

[ELVATO]

In the circuit, the dash illumination is the B arrow. All that it shows for that is the wire going to a group of bulbs, then to ground.

 

[Thermo]

pooleo8, from the sounds of things you have somehow shorted out the dash lights to chassis ground and you are overloading the dimmer circuit. As for fixing it, welcome to the world of a new headlight switch. But, I would only install the headlight switch after figuring out where the wiring is shorted to ground. Odds are, since you just did the instrument cluster, it is either going to be a stray solder blob that hit the back of the instrument cluster or you managed to pinch a wire or two in the dash near the instrument cluster.

I know it isn't the words you are wanting to hear, but that is the short of it.

 

[ELVATO]

"...but that's the short of it."

No pun intended

 

[tsingson]

And that's it for today's "Ask Thermo"...

 

[Thermo]

*takes a bow*

A comedian and a teacher all in one. LMAO.

 

[pooleo8]

It seems as tho it should blown a fuse if there was a dead short. It was strange. The cluster lights did come on, but started dark and slowly got up to full. You could watch it get brighter. The dimmer would not dim them down. It did dim the rest of the lights (radio, EATC) I am going to pull it out tomaro and have a looksee. New switches run like $200! WTH!

I got a use switch at the bone yard today, it was all ripped apart, but the circuit board was there. Perhaps I can fix one or the other after I find the problem

 

[pooleo8]

UPDATE:

I looked everything over thoroughly. I found nothing. I went to the local pick n pull, snagged a broken XL f-150 switch. (wanted it for the transistor) And I found an intact switch from an XLT F-150 (no auto Headlight or FOG)

I tried using the transistor in my switch, nothing. Dash lights came on then slowly dimmed out. I tried the intact switch....WIN! it worked. Full dim was available, no burning, no smelling. Left lights on for about 30 min with no problems.

Now to address the fog issue. The new switch I notice pulled out like my other switch. This got the gears turning in the melon. I took both switches apart, looked them over and found that the f-150 switch did not have the inner black piece that the expy had. I removed it to discover it has a slide contact. So when it is pulled, it makes the contact. I removed it, and installed it into the F-150 switch. BINGO! I now have FOGS!!!

So I got a new switch (that doesnt have the face broke off...WIN) was able to keep my fogs...WIN, but lost the auto headlight feature..who cares! lmao

 

[Thermo]

pooleo8, congrats. Sometimes it is the easier things. But, based on what you were describing, I was pretty sure it was wiring. But, I have seen stranger things happen.