Underhood Lamp

2barhaven2 · 02-20-2012, 06:06 PM

Hello fellow members! I'm looking for some help/info. I have an '07 XLR-V. I believe that was the first year that an underhood lamp was not standard equipment. So I bought the lamp, harness, etc. from the dealer here. Under the hood insulator pad there are already holes for the lamp mounting rivets/screws. The insulator even has the outline for the necessary hole to be cut in it for the lamp to shine through. My problem now is that I can't find any fitting/plug on the vehicle wiring harness for the lamp harness to plug into. I suppose it is possible that the main harness was altered for 2007 to eliminate that plug, but I am wondering if someone out there with an '06 V (or earlier XLR) can tell me how and where the lamp harness attaches to their vehicle system, so I can check more carefully. (The '07 service manuals don't seem to show wiring for the lamp, although there are instructions on how to replace the lamp itself)
Hope someone can help me with this!

Stella · 02-20-2012, 06:20 PM

I have a 04 xlr and the under hood light connection is in the crotch of the driver side hood hinge. There is a harness that run's along the top of the inner fender I believe. I remember looking at mine cause the wire loom made a creaking noise when I opened the hood once. Question how the hell does a 90,000 dollar plus car not have a hood light. Hope that helps.

Anthony Cundari · 02-20-2012, 08:00 PM

I took 3 photos of my '07. Wiring at the hinge coming from the light. The connector that it feeds to and the 2 wire pairs coming off the wiring harness between the brake lines. 1 goes to the low brake fluid sensor page 5-138 #(3); the other goes to the light.

2barhaven2 · 02-21-2012, 09:46 AM

Thanks folks! Looks like my V doesn't have the same wiring; very curious. (If I knew how to post a picture of the same area on my car I would, but I am computer illiterate.) Guess I have outsmarted myself (again!).

2barhaven2 · 02-21-2012, 04:20 PM

Hi again. Thought I should be a bit more detailed than in my earlier reply. My car does not have the plastic(?) connector shown in Anthony's second photo, under the hood strut mount. I wonder if that connector has another purpose as well as connecting the hood light harness to the power supply? I have seen schematics on some of the G.M. parts websites showing a "hood ajar switch" in this area; could this also be part of this connector? (Interestingly, the schematics on my dealer's system don't include any reference to such a switch.) Does anyone know if the hood lamp requires a feed from/to a hood ajar switch/sensor in addition to the mercury switch in the lamp?

Also my car also has only one wire coming off the harness below the master cylinder. There is no second take-off going to the hood light harness. So I will probably have to tap into an existing harness or the fuse box directly. Any advice? And thanks again Stella and Anthony for your quick help already.

Stella · 02-24-2012, 02:21 PM

Hey no problem. The car is new to me any excuse to get to know her a little better is also good for me. I looked on my disc manual and it says that the hood light is powered by batt. Supply " duh" by a orange wire along with ground. I looked at mine and the wires come from the loom that supplies the brake revs. Wires "black- purple". So I guess you want to look for a orange and a black wire with a weather pak connect. If theirs no wires tried to find a power source in the area but b careful of what u tap into or tap into spare power supply at fuse box and somehow run wires in looming. Would think if it's a option on the car "weird" that the wiring would b their. The wiring diagram on the disc is in minature and from what I can read the power for the hood lamp comes from some courtesy lamps power source so maybe try to stay in the courtesy lighting circuit to not affect any other circuits. Good luck!

Anthony Cundari · 02-24-2012, 08:36 PM

1st picture is the harness with a white sheet underneath
2nd picture is top down showing the wiper and the harness from the hood
3rd & 4th pictures are closeups to the left of the wiper

2barhaven2 · 02-26-2012, 07:42 PM

Thanks again to both of you! Stella, I don't think the lamp was technically an "option"; it was standard equipment up to some point, then vanished! The extra pictures are really helpful; thanks Anthony for taking all that further time. My V definitely does not have the necessary wiring for the lamp. Only one wire coming off the loom under the master cylinder, etc. But the new pictures help a lot in figuring out where to route the lamp harness into the engine bay. I will have to tap into an existing circuit somewhere, and ideally it would be where the second wire connects to the loom in cars with the lamp installed from the factory.(Why on earth GM discontinued the lamp in the first place mystifies me!)

pcm2a · 02-26-2012, 08:01 PM

Quote:

Originally Posted by Stella

I looked on my disc manual and it says that the hood light is powered by batt. Supply

Where is the battery located that powers the hood lamp?

I just got my 2006 XLR a week ago and I went out after reading this thread to check mine. The lamp is there (obviously) but no light is on. I popped the light out and it appears to not be burned out, a continuity test also shows it to be good. I poked my volt-meter in the light socket and it doesn't seem to be getting power. If it is really powered by a crappy battery then it is probably dead.

2barhaven2 · 02-26-2012, 08:23 PM

Although my car doesn't have the lamp at all (yet!), as I understand it there should be a plastic-insulated cable from the lamp exiting the left rear corner of the hood, running down into the engine bay to a clip on the left inner fender immediately under the left hood strut pivot just forward of the firewall. A wire goes from that clip to join into another insulated cable under the master cylinder. Main vehicle battery power flows from that last cable up to the clip, from there into the hood lamp cable, and up into the lamp. So the power supply to the lamp is from the main vehicle 12-volt system. The lamp itself has a mercury switch built into it, which should close the circuit when the hood is lifted, thus lighting the bulb. Congrats on your new XLR by the way!

pcm2a · 02-26-2012, 08:43 PM

Thanks so much for that reply. I went back out and smacked on the mercury switch and nothing changed. Next I followed the wires from the hood to the engine and there was a plug that was unplugged! I plugged that joker in and the light works fine. I also verified that as I close the hood the light goes off. I wonder why someone would have unplugged it? Maybe it was running the battery down somehow or maybe they were working on the car and it was blinding them, it is pretty bright.

onalaska · 02-27-2012, 09:34 AM

At car shows and such where your hood is up it's not a good idea to leave that lamp on all day so I just removed mine. Not going to work on it in the dark anyway! Mine never uses any oil so I don't even need it to read the dip stick.

pcm2a · 02-27-2012, 10:05 AM

A car show would make perfect sense. That plug is easily accessible and would only take seconds to plug or unplug. Once spring gets here she may make a few trips to the local car gathering near me :-)

jjsea55 · 02-27-2012, 04:42 PM

My hood and trunk lamps turn off automatically after 20 minutes or so of continuous hood or trunk ajar. I presume this is a lamp/battery saving function of one of the on-board computer circuits.

XFireXLR · 02-28-2012, 03:45 AM

Quote:

Originally Posted by jjsea55

My hood and trunk lamps turn off automatically after 20 minutes or so of continuous hood or trunk ajar. I presume this is a lamp/battery saving function of one of the on-board computer circuits.

Ditto....mine does the same.