Took a spare one apart to see how it works.
You must drill out the rivets, fairly simple, just keep a little pressure on the cover so it don't pop off.
Here's the inside, the two brass circles were contaminated with junk, I cleaned them with dry scotchbrite.
Clean the mating contacts too. (on top cover)


Here's where the major problem is, the mercury bulb may not be making good contact because of corrosion. In this photo the actual brass contact that touches the right-side, center "nipple" of the mercury capsule is missing!


Clean all the corrosion in the capsule's cradle


Once cleaned up, and no wires are frayed, (and bulb works) it will be "high powered" again.
If found that where the bulb wire goes into the case, the hole is too small and restricts the wire from moving in and out of the cassette easily. (you pull it out and it wont go back in). Its not a weak spring, it's wire restriction. I used an X-acto knife and enlarged the hole. Works beautifully now.

 

I cleaned mine up many years ago and got it working. After it failed again years later I decided the damn thing wasn't worth fooling with.

 

Rep's to you, Ron! I have a working one and a couple that don't. May just take one apart some day and fix it, now that you showed me how.

 

Very Simple design. when drilling out the rivets flip it so you see the bottom of the rivets, easy to drill this way, then flip it over and carefully take the top off. Ya do it right and the center spring will not unwind on you.

 

would you happen to know the correct mounting position on the hood?

 

 

Thanks Ctubutis!
Care to explain the small airhorn on the air cleaner, or is that country "Ram Air" mod?

 

Yes, and thanks for asking.

 

You sound like my wife.............

 

I feel special since I KNOW what you think of her. So, to be compared to her.....

 

Great thread! I'll have to investigate mine soon.

 

Bulb type 89 or 105.

The air horns, that's not my truck, no idea there...

 

I acquired one of the underhood lights years ago and I think it is a fantastic and useful feature. I use it all the time. However, I thought it made more sense to mount it on the drivers side of the hood where it can light up the engine oil dipstck, master cyl, rad reservoir, pwr. steering, and windshield washer reservoir. The only thing it was doing over on the other side was to light up the spare tire jack area.

 

The light pulls out and retracts!!

 

you can light up the rear bumper, or change a rear tire with it extended out.