I wanted some engine bay lighting, so I went to
the local junkyard and acquired 3 underhood lights from upper end
GM products. 2 Buicks and a Cadillac I think. They
were the kind that had a hood (light shield) not just a bare
bulb. The junkyard guy charged me $5!!! Highway
I installed 2 of them on the cross bar of the under hood support. In order to position the lights so that they wouldn't shine in my eyes when on, I bent the brackets so that when the hood was up the lights were almost horizontal.
While trying to figure out where I would mount the relay and push switch that would turn the lights on when the hood was opened I decided to test the circuit and see if the lights would come on. No Joy :( Bummer neither light worked. So I started tracing the circuit testing at every point. 12vdc everywhere....Except when I removed the bulbs. At the bulb contact point there was only about 2-3 vdc. :( What the ......Check double check and recheck Yep only 2 - 3 vdc at each socket. That can't be right!!
So I dissemble the 3rd light, low and behold, guess what. The light sockets come with a tilt switch!!! I should of known. When I looked at the cars in the junk yard I didn't see any switch to indicate that the hood was open. I just thought I couldn't locate it cause I didn't know where to look. Which turned out to be true, except instead of switching on upon hood opening, the tilt switch turns the lights on when they are tilted at a certain angle. :)
The tilt switch is the bullet shaped object in the picture below.
So back to the Trooper, and jumper the lights to the battery, and reinstall the bulbs. Then, I rebend the brackets so that the lights are at a slight angle and BINGO on they come!!! and they switch off when the Hood is closed. This makes the install a LOT EASIER!! Now instead of having to install a push switch and a relay, all that is needed is a power circuit from the battery, and an inline fuse. That makes it a really simple and easy install!!! The only draw back is that the lamp hood no longer shields the light at eye level
Last night after it got dark, I went out and checked it out. This photo was taken without the flash. The two bulbs really brightened up the bay, no need for a flashlight to check things out after dark any more. :)
This is an easy modification to make and total cost was less than $7 for the lights, wire, connectors and fuse. The tilt switches inside of the lights make the installation really simple.