Sep 10, 2024
4
2
VetteCoins
90
Car
95 C4
Province
ON
Asking for a friend....no really. My 88 year old neighbour has a 95 C4 that is his baby. He asked me to give him a hand as he thought he had a bad motor on the drivers side headlight. He had already ordered the new motor and tinkered a bit, but he was still having issues. As I understand it the original issue was the drivers side headlight was only partially opening.
He told me that he had replaced the drive motor but he realized that the issue was actually created by a slight bend in the bracket that limited travel. He repaired this and the mechanism ran smooth. So he put the old drive motor back in, everything in the identical position it was when he removed it. The problem he has now is that the lights rotate out of sequence, one up one down. If you manually match the light position the bad light (drivers side) does not move when you turn the lights on (the good one does), but immediately moves open when you turn the lights off.
I took a look and he demonstrated. The good headlight is in the closed position, the bad (or out of sequence driver side) has been manually adjusted to match. Turn on the ignition, sequence the lights. The good passenger side rotates to open, the bad drivers side does not move. Sequence the lights again and the bad drivers side immediately rotates open while the good passenger side closes. They remain out of sequence from then on. We manually matched them again but they remain out of sequence (the bad drivers side ignores the first actuation, then moves on the second placing it our of sequence again). We even tried mismatching them to start off knowing the first actuation would be ignored by the bad drivers side. Magically, when out of sequence it works on the first actuation to ensure they stay mismatched

The system is not that complicated so we are dumbfounded as to how two intelligent people cannot devise a solution. No matter what we try the lights are determined to operate out of sequence (one in one out). The drive motor is good, the gears are intact and move smoothly both manually and when driven by the motor. The wiring is factory and intact. We have tried cycling with the bad light unplugged first then plugging it in, no change. All he did was remove the motor and replace it again, no gearing was touched and the headlight remained mounted and in place the entire time.

Youtube has many great videos on the service, repair and replacement of the lights, but I have yet to find anything that mentions this or how to ensure its correct while repairing or replacing.

Any advice on this topic would be greatly appreciated. He is at the point of wanting to take it to a mechanic and I don't want him to spend the money.

Posted originally in the C4 forum, a member suggest I move it here for better response.

Thank you
G
 
Thats a doozy. (mines been in the shop for two weeks trying to figure out why it doesn't run properly, but that's a different doozy)
The motors , I believe, reverse direction when opening or closing, which would seem like a reversed connection, but you say you've double checked all that. You might try Corvette Central, they have a lot of repair videos, maybe a phone call to Race Ready Corvettes.
Also try and google C4 headlight synchronization. I did a quick look, and there appears to be some info. Good Luck
 
Last edited:
Asking for a friend....no really. My 88 year old neighbour has a 95 C4 that is his baby. He asked me to give him a hand as he thought he had a bad motor on the drivers side headlight. He had already ordered the new motor and tinkered a bit, but he was still having issues. As I understand it the original issue was the drivers side headlight was only partially opening.
He told me that he had replaced the drive motor but he realized that the issue was actually created by a slight bend in the bracket that limited travel. He repaired this and the mechanism ran smooth. So he put the old drive motor back in, everything in the identical position it was when he removed it. The problem he has now is that the lights rotate out of sequence, one up one down. If you manually match the light position the bad light (drivers side) does not move when you turn the lights on (the good one does), but immediately moves open when you turn the lights off.
I took a look and he demonstrated. The good headlight is in the closed position, the bad (or out of sequence driver side) has been manually adjusted to match. Turn on the ignition, sequence the lights. The good passenger side rotates to open, the bad drivers side does not move. Sequence the lights again and the bad drivers side immediately rotates open while the good passenger side closes. They remain out of sequence from then on. We manually matched them again but they remain out of sequence (the bad drivers side ignores the first actuation, then moves on the second placing it our of sequence again). We even tried mismatching them to start off knowing the first actuation would be ignored by the bad drivers side. Magically, when out of sequence it works on the first actuation to ensure they stay mismatched

The system is not that complicated so we are dumbfounded as to how two intelligent people cannot devise a solution. No matter what we try the lights are determined to operate out of sequence (one in one out). The drive motor is good, the gears are intact and move smoothly both manually and when driven by the motor. The wiring is factory and intact. We have tried cycling with the bad light unplugged first then plugging it in, no change. All he did was remove the motor and replace it again, no gearing was touched and the headlight remained mounted and in place the entire time.

Youtube has many great videos on the service, repair and replacement of the lights, but I have yet to find anything that mentions this or how to ensure its correct while repairing or replacing.

Any advice on this topic would be greatly appreciated. He is at the point of wanting to take it to a mechanic and I don't want him to spend the money.

Posted originally in the C4 forum, a member suggest I move it here for better response.

Thank you
G
C4 headlight synchronization
Issues with C4 Corvette headlight synchronization often stem from mechanical or electrical failures in the pop-up headlight system. Here are some common problems and solutions:

- **Out of Sync Headlights**: If one headlight operates slower than the other or they are out of sync, it may be due to a malfunctioning motor or gear. Manually cranking both headlights to the closed position can sometimes reset the system, allowing them to function correctly when activated[4][5].

- **Bad Control Module**: A faulty headlight control module can prevent the headlights from raising or lowering properly. This module controls the motors and can fail due to worn-out relay lines, particularly if the motors are aging and require more power[1][2].

- **Worn Gears**: The gears within the headlight motors can wear out, causing a "thunk" sound and preventing smooth operation. Rebuilding or replacing these gears can resolve the issue[3].

- **Electrical Connections**: Corroded or loose connections can lead to synchronization problems. Cleaning and securing all connections is essential for reliable operation[2].

Regular maintenance and inspection of these components can help keep the pop-up headlights functioning properly.

Sources
[1] C4 Corvette Headlight Controller Repair - Instructables C4 Corvette Headlight Controller Repair (https://www.instructables.com/C4-Corvette-Headlight-Controller-Repair/)
[2] Most common Corvette C4/C5 Pop Up Headlight Issues (Quick ... Most common Corvette C4/C5 Pop Up Headlight Issues (Quick Solutions) - B Pro Wholesale (https://bprowholesale.com/2021/02/23/most-common-corvette-c5-pop-up-headlight-issues-quick-solutions/)
[3] C4 Corvette HEADLIGHT MOTOR REPAIR: 5 Useful Tips - YouTube
[4] Headlights out of sync! - Chevrolet Corvette Forum Discussion Headlights out of sync! - CorvetteForum - Chevrolet Corvette Forum Discussion (https://www.corvetteforum.com/forums/c4-tech-performance/2592699-headlights-out-of-sync.html)
[5] Headlight doors out of sync : r/Corvette - Reddit
[6] One slow headlight | Chevy Corvette Forum https://www.smokinvette.com/threads/one-slow-headlight.62634/
[7] 1984-89 C4 chevrolet CORVETTE Passenger Right Headlight assy ... https://www.ebay.ca/itm/254488790001
[8] 2x H1 Led Light Canbus Bulb Car Headlight High Beam Power Auto ... https://www.aliexpress.com/item/325...andl_currency=USD&_randl_shipto=US&src=google
 
C4 headlight synchronization
Issues with C4 Corvette headlight synchronization often stem from mechanical or electrical failures in the pop-up headlight system. Here are some common problems and solutions:

- **Out of Sync Headlights**: If one headlight operates slower than the other or they are out of sync, it may be due to a malfunctioning motor or gear. Manually cranking both headlights to the closed position can sometimes reset the system, allowing them to function correctly when activated[4][5].

- **Bad Control Module**: A faulty headlight control module can prevent the headlights from raising or lowering properly. This module controls the motors and can fail due to worn-out relay lines, particularly if the motors are aging and require more power[1][2].

- **Worn Gears**: The gears within the headlight motors can wear out, causing a "thunk" sound and preventing smooth operation. Rebuilding or replacing these gears can resolve the issue[3].

- **Electrical Connections**: Corroded or loose connections can lead to synchronization problems. Cleaning and securing all connections is essential for reliable operation[2].

Regular maintenance and inspection of these components can help keep the pop-up headlights functioning properly.

Sources
[1] C4 Corvette Headlight Controller Repair - Instructables C4 Corvette Headlight Controller Repair (https://www.instructables.com/C4-Corvette-Headlight-Controller-Repair/)
[2] Most common Corvette C4/C5 Pop Up Headlight Issues (Quick ... Most common Corvette C4/C5 Pop Up Headlight Issues (Quick Solutions) - B Pro Wholesale (https://bprowholesale.com/2021/02/23/most-common-corvette-c5-pop-up-headlight-issues-quick-solutions/)
[3] C4 Corvette HEADLIGHT MOTOR REPAIR: 5 Useful Tips - YouTube
[4] Headlights out of sync! - Chevrolet Corvette Forum Discussion Headlights out of sync! - CorvetteForum - Chevrolet Corvette Forum Discussion (https://www.corvetteforum.com/forums/c4-tech-performance/2592699-headlights-out-of-sync.html)
[5] Headlight doors out of sync : r/Corvette - Reddit
[6] One slow headlight | Chevy Corvette Forum https://www.smokinvette.com/threads/one-slow-headlight.62634/
[7] 1984-89 C4 chevrolet CORVETTE Passenger Right Headlight assy ... https://www.ebay.ca/itm/254488790001
[8] 2x H1 Led Light Canbus Bulb Car Headlight High Beam Power Auto ... https://www.aliexpress.com/item/325...andl_currency=USD&_randl_shipto=US&src=google

Thank you! I will look into all the links. All the basics have been covered. Functionality is 100% just in opposite directions.
 
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