Headlights won’t open
Former Vendor
Joined: Dec 2016
Posts: 3,574
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From: Lookin over Hoover Dam
If neither open, then it'd require more than one fuse is blown then...I'd start earlier in the system...i.e. the switch. My car sat for some years and actually wouldn't open the headlights either...once I worked the switch back and forth it worked fine. Same happened with the windows. Like anything, there's a diagnostic workflow but, if neither open or work, then it's going to be starting with verifying the switch is working.
Pro
Joined: Dec 2013
Posts: 627
Likes: 181
From: west coast of Canada
Start with insuring the battery is at full charge. A battery at full charge will measure between 12.7 and 12.9 volts or more when measured across the battery posts with the neg cable disconnected. Don't bother with the dash voltage gauges as they report the state of health of the charging system and NOT the state of health of the battery. I would also get the battery load tsted. Most parts stores will do that free.
Once the battery is KNOWN good you can check the condition of the headlight control module. It is the HCM that senses current flow in the headlight motor circuit and shuts off the motor when the current rises to a set amount. The HCM is known for having the plastic case of the module fail allowing moisture and dirt into the electronics. HCM looks like this:
http://www.ebay.com/itm/97-98-99-00-...5Y0ETl&vxp=mtr
and is located on the passenger side below the headlight assembly.
Nope... Not weird at all. Pretty common C5 headlight problem.
Close bump stops are worn/damaged or missing. When the motor closes the headlight doors the bump stops are contacted causing the current in the motor circuit to begin to rise. The headlight control module senses the current rise and shuts off the voltage to the motors. If the bump stops are missing or damaged the motor over rotates the doors before the voltage is shut off causing them to have excess tension on the gears that will shut off the motors on the OPEN because the current in the circuit rises before the doors open and the control module thinks they have opened and hit the bup stops for open.
Examine the bump stops for CLOSE and turn them around if they can be or order replacements. Here is a link to a thread that shows both the open and close bump stops:
https://www.corvetteforum.com/forums/...ght-shake.html
GM no longer has replacements so order from the only source I know of:
http://rodneydickman.com/catalog/pro...roducts_id=309
Last edited by 8VETTE7; 10-11-2017 at 07:03 AM. Reason: Sp
Once the battery is KNOWN good you can check the condition of the headlight control module. It is the HCM that senses current flow in the headlight motor circuit and shuts off the motor when the current rises to a set amount. The HCM is known for having the plastic case of the module fail allowing moisture and dirt into the electronics. HCM looks like this:
http://www.ebay.com/itm/97-98-99-00-...5Y0ETl&vxp=mtr
and is located on the passenger side below the headlight assembly.
Nope... Not weird at all. Pretty common C5 headlight problem.
Close bump stops are worn/damaged or missing. When the motor closes the headlight doors the bump stops are contacted causing the current in the motor circuit to begin to rise. The headlight control module senses the current rise and shuts off the voltage to the motors. If the bump stops are missing or damaged the motor over rotates the doors before the voltage is shut off causing them to have excess tension on the gears that will shut off the motors on the OPEN because the current in the circuit rises before the doors open and the control module thinks they have opened and hit the bup stops for open.
Examine the bump stops for CLOSE and turn them around if they can be or order replacements. Here is a link to a thread that shows both the open and close bump stops:
https://www.corvetteforum.com/forums/...ght-shake.html
GM no longer has replacements so order from the only source I know of:
http://rodneydickman.com/catalog/pro...roducts_id=309
Last edited by 8VETTE7; 10-11-2017 at 07:03 AM. Reason: Sp
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Issue with my headlights aswell (2004 c5)
Im having an issue where my left headlight wont open, my right opens just fine but whats odd to me is the left one will open by hand and the right wont, also the little **** next to it (im very un mechanically skilled) im assuming this is the motor. The left side spins by hand very loosely and never gets tight where as the right side is tight to turn. Is this a headlight motor issue or could it be something else?
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Safety Car
Joined: Jan 2014
Posts: 4,496
Likes: 855
From: Walhalla South Carolina
Im having an issue where my left headlight wont open, my right opens just fine but whats odd to me is the left one will open by hand and the right wont, also the little **** next to it (im very un mechanically skilled) im assuming this is the motor. The left side spins by hand very loosely and never gets tight where as the right side is tight to turn. Is this a headlight motor issue or could it be something else?
Replace motor, motor is around 130.00, 30 minute job, several youtube how to out there.
Owner Foxbat Motorsports
Joined: Dec 2024
Posts: 3
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From: Alexander, ME
Thank you
Start with insuring the battery is at full charge. A battery at full charge will measure between 12.7 and 12.9 volts or more when measured across the battery posts with the neg cable disconnected. Don't bother with the dash voltage gauges as they report the state of health of the charging system and NOT the state of health of the battery. I would also get the battery load tsted. Most parts stores will do that free.
Once the battery is KNOWN good you can check the condition of the headlight control module. It is the HCM that senses current flow in the headlight motor circuit and shuts off the motor when the current rises to a set amount. The HCM is known for having the plastic case of the module fail allowing moisture and dirt into the electronics. HCM looks like this:
http://www.ebay.com/itm/97-98-99-00-...5Y0ETl&vxp=mtr
and is located on the passenger side below the headlight assembly.
Nope... Not weird at all. Pretty common C5 headlight problem.
Close bump stops are worn/damaged or missing. When the motor closes the headlight doors the bump stops are contacted causing the current in the motor circuit to begin to rise. The headlight control module senses the current rise and shuts off the voltage to the motors. If the bump stops are missing or damaged the motor over rotates the doors before the voltage is shut off causing them to have excess tension on the gears that will shut off the motors on the OPEN because the current in the circuit rises before the doors open and the control module thinks they have opened and hit the bup stops for open.
Examine the bump stops for CLOSE and turn them around if they can be or order replacements. Here is a link to a thread that shows both the open and close bump stops:
https://www.corvetteforum.com/forums/...ght-shake.html
GM no longer has replacements so order from the only source I know of:
http://rodneydickman.com/catalog/pro...roducts_id=309
Last edited by 8VETTE7; 10-11-2017 at 07:03 AM. Reason: Sp
Once the battery is KNOWN good you can check the condition of the headlight control module. It is the HCM that senses current flow in the headlight motor circuit and shuts off the motor when the current rises to a set amount. The HCM is known for having the plastic case of the module fail allowing moisture and dirt into the electronics. HCM looks like this:
http://www.ebay.com/itm/97-98-99-00-...5Y0ETl&vxp=mtr
and is located on the passenger side below the headlight assembly.
Nope... Not weird at all. Pretty common C5 headlight problem.
Close bump stops are worn/damaged or missing. When the motor closes the headlight doors the bump stops are contacted causing the current in the motor circuit to begin to rise. The headlight control module senses the current rise and shuts off the voltage to the motors. If the bump stops are missing or damaged the motor over rotates the doors before the voltage is shut off causing them to have excess tension on the gears that will shut off the motors on the OPEN because the current in the circuit rises before the doors open and the control module thinks they have opened and hit the bup stops for open.
Examine the bump stops for CLOSE and turn them around if they can be or order replacements. Here is a link to a thread that shows both the open and close bump stops:
https://www.corvetteforum.com/forums/...ght-shake.html
GM no longer has replacements so order from the only source I know of:
http://rodneydickman.com/catalog/pro...roducts_id=309
Last edited by 8VETTE7; 10-11-2017 at 07:03 AM. Reason: Sp