C5 Headlights Won't Shut... Help Please
Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 21
Likes: 3
C5 Headlights Won't Shut... Help Please
Hello friends,
I am stumped. I have a 2002 C5 in like new condition. I am the original owner, only 30K miles. Yesterday i parked it in my garage and shut the engine and noticed the headlights shut off of the lights didn;t recess... the stayed up in the on position. Even if i turn the control to off, the headlights still stay up. I then noticed at night, when i turned the car on, the lights went on (with them still in the up position...they still are not going up or donw) but the dash lights stayed dark when the engine was on..when i shut the engine off, the dash lights went on and headlights turned off but stay in the up position and didnt recess. Does this make sense? is it something that I may have pressed or done myself ? is this common or an easy fix? Any help much appreciated before I have to take it to a dealer and get fleeced with the service charge no doubt. Many thanks and have a great weekend.
Cheers!
Joey
I am stumped. I have a 2002 C5 in like new condition. I am the original owner, only 30K miles. Yesterday i parked it in my garage and shut the engine and noticed the headlights shut off of the lights didn;t recess... the stayed up in the on position. Even if i turn the control to off, the headlights still stay up. I then noticed at night, when i turned the car on, the lights went on (with them still in the up position...they still are not going up or donw) but the dash lights stayed dark when the engine was on..when i shut the engine off, the dash lights went on and headlights turned off but stay in the up position and didnt recess. Does this make sense? is it something that I may have pressed or done myself ? is this common or an easy fix? Any help much appreciated before I have to take it to a dealer and get fleeced with the service charge no doubt. Many thanks and have a great weekend.
Cheers!
Joey
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Joined: Dec 2017
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From: Virginia
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This should probably be posted in the tech section. However, I can give you at least some info. The lights are turning on and off because you have twilight sentinel turned on. However, the lights should be going up and down as well. It is common for the gear in the headlight motors to get stripped. However, based on your description, I don't think that's your issue. Maybe a fuse has blown? FYI, you should be able to manually lower the headlights by twisting the **** just behind each headlight.
Pro
Joined: Jun 2022
Posts: 691
Likes: 317
From: NW OH
Well, whenever I get something that turns on when something else unrelated is supposed to turn off it's check the grounds and plugs to make sure all the connections are good. There might be a backfeeding situation. The module that controls the lamp motors is on the right side in front so I would start by looking at the grounds there (g102) and also near the bcm and ipc.
Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 21
Likes: 3
Thanks everyone,... No I havent changed the bulbs. This happened all of a sudden. Will try what is suggested... but I guess I will have to take to a Chevy Dealer and get fleeced on the the check up and repair. I tried to look online or youtube for any guidance and nothing. Totally bizarre
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Moved this to C5 Tech.
Pro
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You might want to check this out...
First let’s make sure it’s your HCM that’s bad.
• Check Fuses 3 and 4 in under hood fuse box
• Check Fuse 6 in fuse box under passenger side floorboard
• Raise passenger side headlight
• Remove 3 Phillips head screws from headlight bezel and remove bezel
• Remove 4 Torx screws from headlight lid (will have lower light some for rear screws)
• Remove nuts from both pivot screws (take care not to drop nuts)
• Support light fixture and remove the pivot screws. Gently lower the fixture out of the way.
• Remove nut from motor drive shaft and remove control arm from shaft. This will get the fixture further out of the way. You can disconnect the bulbs and completely remove the fixture.
• The HCM is mounted on the fender just behind the headlight.
• Remove the two connectors from the HCM
• With headlights off, Use a voltmeter to verify in 5 pin connector
• Neg lead of voltmeter to Pin D (Black Wire) Pos lead to Pin A (White wire) Reading should be zero volts
• Neg lead to Pin D Pos lead to Pin B (Orange wire) Reading should be 12volts
• Neg lead to Pin D Pos lead to Pin C (Dark Green wire) Reading should be 12 volts
• Neg lead to Pin D Pos lead to Pin E (Orange wire) Reading should be 12 volts
• Switch headlights on.
• Neg lead to Pin D Pos lead to Pin A Reading should be 12volts
• Neg lead to Pin D Pos lead to Pin C Reading should be zero volts
• If any of the above tests fail HCM is not the problem. It will probably be fuses, wiring or switch.
• If all of those tests are good, plug 5 pin connector back into HCM
• Connect a test light to HCM 4 pin output Pin A and Pin B
• Turn headlights off and on. Test light should come on momentarily each time you turn off or on.
• Connect the test light to HCM 4 pin output Pin C and Pin D
• Turn headlights off and on Test light should come on momentarily each time you turn off or on.
• If either one of last two tests fail HCM is bad.
• If both of those tests are good problem is either wiring or the motors.
If the HCM is bad, you can try to fix it. Remove the HCM from fender. Look at the back of the module. If the back is loose, water probably got into the circuit board. The back is just stuck on with some tar like stuff. You can easily pry it off with a flat blade screwdriver. I tried re-soldering some of the pads and IT WORKED for about 2 days.
You can get a used one off Ebay. You might even find one new old stock from a dealer.
I saw that one of the popular Corvette catalogs advertises new HCM for about $600.
The motors run one way when the lights are turned on. They run the other way when lights are turned off. The direction is changed by switching the polarity of the wires. There is no switch that determines when light is fully up or fully down. The HCM has a timer circuit that shuts the motors off after a split second. HCM determines polarity based on signals on Pin A or Pin C of 5 pin connector.
First let’s make sure it’s your HCM that’s bad.
• Check Fuses 3 and 4 in under hood fuse box
• Check Fuse 6 in fuse box under passenger side floorboard
• Raise passenger side headlight
• Remove 3 Phillips head screws from headlight bezel and remove bezel
• Remove 4 Torx screws from headlight lid (will have lower light some for rear screws)
• Remove nuts from both pivot screws (take care not to drop nuts)
• Support light fixture and remove the pivot screws. Gently lower the fixture out of the way.
• Remove nut from motor drive shaft and remove control arm from shaft. This will get the fixture further out of the way. You can disconnect the bulbs and completely remove the fixture.
• The HCM is mounted on the fender just behind the headlight.
• Remove the two connectors from the HCM
• With headlights off, Use a voltmeter to verify in 5 pin connector
• Neg lead of voltmeter to Pin D (Black Wire) Pos lead to Pin A (White wire) Reading should be zero volts
• Neg lead to Pin D Pos lead to Pin B (Orange wire) Reading should be 12volts
• Neg lead to Pin D Pos lead to Pin C (Dark Green wire) Reading should be 12 volts
• Neg lead to Pin D Pos lead to Pin E (Orange wire) Reading should be 12 volts
• Switch headlights on.
• Neg lead to Pin D Pos lead to Pin A Reading should be 12volts
• Neg lead to Pin D Pos lead to Pin C Reading should be zero volts
• If any of the above tests fail HCM is not the problem. It will probably be fuses, wiring or switch.
• If all of those tests are good, plug 5 pin connector back into HCM
• Connect a test light to HCM 4 pin output Pin A and Pin B
• Turn headlights off and on. Test light should come on momentarily each time you turn off or on.
• Connect the test light to HCM 4 pin output Pin C and Pin D
• Turn headlights off and on Test light should come on momentarily each time you turn off or on.
• If either one of last two tests fail HCM is bad.
• If both of those tests are good problem is either wiring or the motors.
If the HCM is bad, you can try to fix it. Remove the HCM from fender. Look at the back of the module. If the back is loose, water probably got into the circuit board. The back is just stuck on with some tar like stuff. You can easily pry it off with a flat blade screwdriver. I tried re-soldering some of the pads and IT WORKED for about 2 days.
You can get a used one off Ebay. You might even find one new old stock from a dealer.
I saw that one of the popular Corvette catalogs advertises new HCM for about $600.
The motors run one way when the lights are turned on. They run the other way when lights are turned off. The direction is changed by switching the polarity of the wires. There is no switch that determines when light is fully up or fully down. The HCM has a timer circuit that shuts the motors off after a split second. HCM determines polarity based on signals on Pin A or Pin C of 5 pin connector.