How-To: Install Underhood Light.

mc7719 · January 10, 2011

Well one little option I missed from my '96 was an underhood light. Well I thought this was ridiculous, since my base-model '96 Chev 4x4 had one and my fully-loaded '08 Sierra didn't. So I looked into it a bit further. After asking the dealer who informed me they no longer supplied the part (for any year) I hit the wreckers. I couldn't find an intact one from them either. The common denominator is that they contain MERCURY inside switch built within the light socket unit... and these days... you're not going to find mercury readily available. Hence, GM no longer supplies this "environmentally unfriendly" device (at least that's what they all told me) and the wreckers said they are required to remove the mercury switch portion BEFORE the vehicle goes to the yard, to ensure they are disposed of properly.

So I turned to eBay, and 5 days later had a brand new unit in my mailbox:

So I installed it on one of the metal 'tabs' that help hold the black material to the underside of the hood.

I ground the braided cable to the firewall (even though, with the hood already connected by a ground strap elsewhere, this was redundant) And then bought a 'female' side of the OEM plug to run it through a fuse (10-15A), and then connected it to one of the studs on the under-hood fuse panel (where the power take-off for trailering pkg is)

Below you can see the new looming tied on top the existing, thicker looming along the firewall. Then routed to the right of the fuse box, between the fender.

The fuse and extra wire is hidden under the fuse box cover:

End result (sorry, it was dark and the exposure made the picture blurry, but you get the idea):

When the hood reaches the halfway point between fully open, and closed, the light turns off as the mercury inside the socket moves off the contacts

pwall · January 10, 2011

Great job.

I do miss the underhood light...they are convenient.

tanked_darren · January 11, 2011

Great post I'm ordering one now!

What gauge wire did you use? And the white connector thing in the fuse box? That is the inline fuse you used?

EDIT: Sadly I could not find one that isn't from the 1960's eras cars....

FOUND IT: http://cgi.ebay.ca/NEW-OEM-HOOD-LAMP-LIGHT...=item1e60a3c7e3

mc7719 · January 11, 2011

Great post I'm ordering one now!

What gauge wire did you use? And the white connector thing in the fuse box? That is the inline fuse you used?

EDIT: Sadly I could not find one that isn't from the 1960's eras cars....

FOUND IT: http://cgi.ebay.ca/NEW-OEM-HOOD-LAMP-LIGHT...=item1e60a3c7e3

I used the same wire as what was on the harness the light came with, I think 18ga. And yes the white tube is the fuse. Just an old-style glass one I had lying around (15A)

tanked_darren · January 14, 2011

How did you come to using a 15A fuse?

I robbed a light out of a truck, and I tried to find the fuse in it just to see what GM was going with, but I was in a rush and couldn't find it.

mc7719 · January 14, 2011

Did a rough calculation based on a 55w bulb @12v.. Ideally I would have used a 10A, but 15 is what I had lying around lol

tanked_darren · January 14, 2011

Ok thanks!

RAF · January 14, 2011

Nice job man

I just hope yours works better than mine. Half the time mine doesn't turn on

xPosTech · January 14, 2011

The ideal underhood light is one of the retractable types found on a late 80's to late 90's GM trucks and even a bunch of the cars and wagons. They detach and have about a 20' cord for changing flats, etc. Wind the cord back in the reel when you're finished. Magnetic base on most of them.

Definitely gonna put one on mine when I find it. No reason you couldn't fit it to the hood instead of the original location on the fender or firewall.

I'd check the wrecking yards. You can usually clean up the contacts and reflectors and maybe replace the cord if it's a little rusty. Gargle GM retractable underhood light for new ones but they might run $50-$90.

Ted

mc7719 · January 14, 2011

Nice job man
I just hope yours works better than mine. Half the time mine doesn't turn on

Could it be the angle you have it mounted? The mercury switch needs specific angle to move and turn on/off. I tried a few different places, and "bent" the bracket as necessary to achieve a solid on and off position.

BigBlueLB756 · April 2, 2011

Finally got around to doing this mod today and it works great. Thanks to mc for the idea and tanked for the lead to the ebuy source.

electricchiken7 · April 3, 2011

I think im going to have to try this mod. Where did you find the female connection to the harness. Just regular parts store like Advance or Auto Zone? Thanks for the idea. I wondered why these trucks didn't have these.

BigBlueLB756 · April 3, 2011

Clip off the connector; splice on enough RED wire to reach around to the underhood fuse panel; splice on an inline fuse holder, and end it with a lug for connection to the exterior stud on the fuse panel and you'll be all hooked up. Don't worry about the braided ground; the light is grounded through the screws into the hood.

All the details are in mc's post #1.

Thanks again to mc for this write-up.