LJ72Cut

I am trying to install an under hood lamp for a 72 Olds Cutlass Supreme. I have a fisher book and I have somewhat of an idea where it mounts under the hood but i am not sure where the end plugs into to get power. Also, I'm curious if wherever it plugs into will recognize when the hood is up in order to illuminate and to turn off when the hood is closed. Any advice?

oldspackrat

Look by the master cylinder, down towards the fuse block. There should be a brown wire with a black connector, about 6-8" long maybe? The under hood light should have a small lead connected to another lead about 15" long, plug them all together & attach the light to the 2 small holes at the driver rear of the hood & you should be good to go.

crimsoncolby

X2.

It sounds like you're confused as to how the light goes on and off. The power feed does not control that. It's accomplished via some mercury within the light housing that flows and makes/breaks conductive contact as the hood is raised/lowered.

LJ72Cut

Oldspackrat are you talking about the connector below:



If so, the tail end connector on the lamp (below) does not match up to the connector above. Also where could I find the exact screws to bolt up the light to the hood..any idea of the dimensions of such screws?

oldspackrat

The connector is the right one, here is a picture of one on my '72. Your lamp is the later style found on the late '70s through mid '80s cars I believe. The correct style in shown below. It is attached by 2 5/16" short screws/bolts & has the correct connectors to plug & play for your car. You will have to do some rigging to get yours to work or find the correct style without the black plastic plug under the bulb. I heard they did away with the older version due to the mercury in the switch. It could possibly leak or get into the environment & kill some polar bears you know....

72455

I'm bumping this thread cuz I'm facing the same challenge and it seems that this topic has dropped off the radar. I have the same exact light shown in the pic and I'm not sure how that terminal connector hooks up. About half way up the wire on the new light there is what appears to be a plug. Does that plug come apart and do I just hook the light to my existing wiring or is there cutting and splicing involved?

Thanks,
Dave😀

Junkman

I am far from an Oldsmobile expert, however, I do recognize the terminal end that is shown in the picture above (reposted below). That to me looks like the type of light that was more commonly used on some other GM cars, and the terminal would clip onto the older style voltage regulator battery terminal. The older style of voltage regulator had screw terminals on it, and was used primarily with generators. If this is a reproduction light, the vendor is probably listing it as fitting anything and everything that has wheels under it.
I was sorting parts this past weekend, and happened to find one in a box with a GM label on it, but haven't identified all applications as of yet. I know that it is from around 1978 vintage. It is pictured below, and I believe that your light should have a similar type of wire connection on the end. GM used a variety of connectors through the years, and it shouldn't be difficult to find the correct one for your lamp to connect to the main harness.
The light that I have pictured, also has a pull apart plug that houses a fuse. This plug that you describe as yours having might also be a fused pull apart connector. Give it a twist while gently pulling it apart. That is the only way that you will know if there is a fuse in there.

72455

I checked tonight and I see a brown wire under the master cylinder. This wire connects to another brown wire which runs the entire length of the inner fender well. On the other end is a connector which dead ends next to the washer fluid reservoir. I took the terminal on the end of the wire for the light and kind of plugged it in to the connector both under the master cylinder, and then tried the same thing on the other end and got nothing, even when I grounded the light housing to the battery negative terminal.

Am I missing something?
Thanks,
Dave

oldspackrat

I assume you have a '72 Cutlass? If so, there should be a short brown wire coming from the fuse box, maybe 6" or so? If your car did not come with the courtesy light package, there SHOULD be nothing attached to that wire. If you have the correct under hood light or a hood light with a compatible connector you should be able to just plug it into that brown wire & with the lights on, ground the body of the lamp at an angle that simulates it being mounted on the bottom of the hood & the hood in the open position. Assuming everything is working like it should, you should have light. If not, check for power at the light connector & work your way back to the fuse block.

Yellowstatue

Sometimes the headlight switch has to be on for the under hood light to work.

72455

Thanks for the advice from everyone...got it working😀

oddball

Yup, the '72/'71 ones that I've seen didn't have mercury in the light. They just turned on/off with the headlights.

crimsoncolby

[QUOTE=oddball;1113159]Yup, the '72/'71 ones that I've seen didn't have mercury in the light. They just turned on/off with the headlights.[/QUOT

Huh? Wouldn't that mean the light would be on whenever the headlights were needed regardless of whether the hood was up?

I recently brought home a couple of underhood lights from a '74 & '75 Cutlass and, when bench tested, had to tip the lamp to replicate opening the hood to get them to light. I assumed that was due to the mercury inside acting as a switch of sorts.

anthonyP

I sort of remember the '70 A-body hood light would go on whenever the hood was raised, and the 71 A-body requiring the parking lights to be on. Guessing they both worked with a mercury switch, but the change was made so the bulb was on only when needed.