Hood Light Electrical Question - Multifunction Switch
Thread Starter
Racer
Joined: Apr 2004
Posts: 336
Likes: 0
From: Tucson
Hood Light Electrical Question - Multifunction Switch
Like many, my C5 2001 had headlight lids not closing, no tail lights, no dash lights (unless I changed the twilight option), and occasional turn signal issues. With the aid of excellent forum instructions, I removed the multi-function switch, bent the tabs as instructed, and voila, everything appears to be working.
However, I’m not sure if I have a hood light issue.
If I reach in through the window without opening the door, pop the hood release and raise the hood, no hood light (I do hear the clicking sound near the right headlight). If I open the door and then raise the hood, the light comes on.
After the lights go off (reset), I reach in and press the truck release and the interior light comes on as well as the trunk light. Then if I raise the hood, the light comes on.
I’m pretty sure the hood light should (and use to) come on even if I don’t open the door. Am I going nuts? I’m not an electrical expert, so reading the schematics is like my Klingon language skill… zero. Is this related to the multi-function switch? Something different all together?
I’d like to know what’s up before I re-assemble everything. Any help in shedding some light (pun, pun, pun
) is greatly appreciated.
Thanks
However, I’m not sure if I have a hood light issue.
If I reach in through the window without opening the door, pop the hood release and raise the hood, no hood light (I do hear the clicking sound near the right headlight). If I open the door and then raise the hood, the light comes on.
After the lights go off (reset), I reach in and press the truck release and the interior light comes on as well as the trunk light. Then if I raise the hood, the light comes on.
I’m pretty sure the hood light should (and use to) come on even if I don’t open the door. Am I going nuts? I’m not an electrical expert, so reading the schematics is like my Klingon language skill… zero. Is this related to the multi-function switch? Something different all together?
I’d like to know what’s up before I re-assemble everything. Any help in shedding some light (pun, pun, pun
) is greatly appreciated.Thanks
Thread Starter
Racer
Joined: Apr 2004
Posts: 336
Likes: 0
From: Tucson
The hood light is in no way related to the MFS. It is part of a circuit referred to as "monitored inadvertent load" and uses fuse #2 and relay #37 in the passenger footwell fuse box to control the hood light, the light on the bottom of the interior rear view mirror, the vanity lights on the vanity mirrors and the glove box light. The BCM provides the ground for relay #37 to provide power to those lights and cut off power after about 10-15 minutes if any are "inadvertently" left ON.
Sounds like possibly the BCM is not waking up when the hood is raised unless some other action that could and does wakeup the BCM occurs first. Has the floor in the passenger foot well ever been wet?? Are there any white stains on the aluminum can that the BCM board is inside of in the passenger foot well? Have you ever cleaned the rubber udders for the wiper well drains or the udder for the AC condensate drain??? Getting the BCM wet can causeall sorts of strange electrical symptoms.
The BCM goes into sleep mode after about 10 minutes when there is no activity for it to manage. It gets awakened by any number of things under normal conditions including opening the hood and opening the glove box or opening the cover on the vanity mirror or opening the car door or trunk lid........etc.
I would check the things I mentioned above as well as swap relay #37 with another relay to see if that makes any difference. You can also check the grounds in the car to see if any are corroded. Specifically I would be checking ground G102 which is in the engine compartment on the right side frame toward the front of the car.
Here are a couple of links about grounds in the C5. Probably a good idea to check all of them to insure they are clean and tight:
http://forums.corvetteforum.com/c5-t...locations.html
http://forums.corvetteforum.com/c5-t...tion-long.html Post #1
Corroded grounds are the source of untold C5 problems...
Sounds like possibly the BCM is not waking up when the hood is raised unless some other action that could and does wakeup the BCM occurs first. Has the floor in the passenger foot well ever been wet?? Are there any white stains on the aluminum can that the BCM board is inside of in the passenger foot well? Have you ever cleaned the rubber udders for the wiper well drains or the udder for the AC condensate drain??? Getting the BCM wet can causeall sorts of strange electrical symptoms.
The BCM goes into sleep mode after about 10 minutes when there is no activity for it to manage. It gets awakened by any number of things under normal conditions including opening the hood and opening the glove box or opening the cover on the vanity mirror or opening the car door or trunk lid........etc.
I would check the things I mentioned above as well as swap relay #37 with another relay to see if that makes any difference. You can also check the grounds in the car to see if any are corroded. Specifically I would be checking ground G102 which is in the engine compartment on the right side frame toward the front of the car.
Here are a couple of links about grounds in the C5. Probably a good idea to check all of them to insure they are clean and tight:
http://forums.corvetteforum.com/c5-t...locations.html
http://forums.corvetteforum.com/c5-t...tion-long.html Post #1
Corroded grounds are the source of untold C5 problems...
Thanks for all the great info. Good to know that it's not related to the MFS so I can re-assemble that area. I live in the desert and other then getting caught in torrential rain and deep water 3 years ago, I doubt it's corrosion.
I'll check out your leads after the MFS project.
Drifting
Joined: Feb 2003
Posts: 1,761
Likes: 235
From: North Carolina
Thanks for all the great info. Good to know that it's not related to the MFS so I can re-assemble that area. I live in the desert and other then getting caught in torrential rain and deep water 3 years ago, I doubt it's corrosion.
I'll check out your leads after the MFS project.
I'll check out your leads after the MFS project.
Last edited by MAC5; Aug 3, 2016 at 09:44 AM.
Thread Starter
Racer
Joined: Apr 2004
Posts: 336
Likes: 0
From: Tucson
Is the relay an auto parts store replacement item or better to get a GM part?
Last edited by Ran-D; Aug 5, 2016 at 01:41 AM.
