Strange headlight door problem
Thread Starter
3rd Gear
Joined: Oct 2011
Posts: 3
Likes: 1
Strange headlight door problem
Hi,
After enough troubles with deteriorated vacuum hoses and parts I decided to replace all the headlight door vacuum parts: actuators, relays, check valve, filter and all the hoses between these parts. Now it's done but I still have a weird problem:
When I start the engine (lights off) both the headlight doors open up. In a few seconds they close again. And after that everything works perfectly: the headlight doors open and close as they should when turning the lights on and off. But what could be the reason for the lights popping up and then immediately closing down when starting the engine??
Thx!!
After enough troubles with deteriorated vacuum hoses and parts I decided to replace all the headlight door vacuum parts: actuators, relays, check valve, filter and all the hoses between these parts. Now it's done but I still have a weird problem:
When I start the engine (lights off) both the headlight doors open up. In a few seconds they close again. And after that everything works perfectly: the headlight doors open and close as they should when turning the lights on and off. But what could be the reason for the lights popping up and then immediately closing down when starting the engine??
Thx!!
Race Director
Joined: Mar 2010
Posts: 16,012
Likes: 827
We recognize you're having challenges with your headlights doors and want to help make this situation right, Mika. For assistance, please visit: https://s.chevy.com/support-request and fill out the support request form with all the requested details. This form helps our team gather the right information and ensures your request is routed appropriately. Our team looks forward to assisting you further.
Team Owner
Joined: Sep 2006
Posts: 31,270
Likes: 4,362
From: Westminster Maryland
Hello,
2 size hoses
LARGE.... supply the vacuum to open and close the doors. Actuators.
small....supply the vacuum to CONTROL the doors. Switches and relays.
2 small hoses at the headlight switch. One black w/blue stripe and one plain black.
Are these in the right position? Blue on the nipple towards the front of the car.
Some sources show them reversed.
Regards....
2 size hoses
LARGE.... supply the vacuum to open and close the doors. Actuators.
small....supply the vacuum to CONTROL the doors. Switches and relays.
2 small hoses at the headlight switch. One black w/blue stripe and one plain black.
Are these in the right position? Blue on the nipple towards the front of the car.
Some sources show them reversed.
Regards....
Last edited by Alan 71; Apr 30, 2026 at 02:26 PM.
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
We recognize you're having challenges with your headlights doors and want to help make this situation right, Mika. For assistance, please visit: https://s.chevy.com/support-request and fill out the support request form with all the requested details. This form helps our team gather the right information and ensures your request is routed appropriately. Our team looks forward to assisting you further.
Drifting
Joined: Nov 2013
Posts: 1,572
Likes: 486
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
We recognize you're having challenges with your headlights doors and want to help make this situation right, Mika. For assistance, please visit: https://s.chevy.com/support-request and fill out the support request form with all the requested details. This form helps our team gather the right information and ensures your request is routed appropriately. Our team looks forward to assisting you further.
Advanced
Joined: Apr 2026
Posts: 50
Likes: 8
From: Southeast Massachusetts
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Racer
Joined: Sep 2024
Posts: 257
Likes: 26
Hi,
After enough troubles with deteriorated vacuum hoses and parts I decided to replace all the headlight door vacuum parts: actuators, relays, check valve, filter and all the hoses between these parts. Just like choosing the right style matters, whether it is high fade haircut styles for black men or finding the perfect fix for your car, now it is done but I still have a weird problem.
When I start the engine (lights off) both the headlight doors open up. In a few seconds they close again. And after that everything works perfectly: the headlight doors open and close as they should when turning the lights on and off. But what could be the reason for the lights popping up and then immediately closing down when starting the engine??
Thx!!
After enough troubles with deteriorated vacuum hoses and parts I decided to replace all the headlight door vacuum parts: actuators, relays, check valve, filter and all the hoses between these parts. Just like choosing the right style matters, whether it is high fade haircut styles for black men or finding the perfect fix for your car, now it is done but I still have a weird problem.
When I start the engine (lights off) both the headlight doors open up. In a few seconds they close again. And after that everything works perfectly: the headlight doors open and close as they should when turning the lights on and off. But what could be the reason for the lights popping up and then immediately closing down when starting the engine??
Thx!!
Advanced
Joined: Apr 2026
Posts: 50
Likes: 8
From: Southeast Massachusetts
When you start the engine, there is a brief moment before the vacuum system builds up sufficient pressure. This pressure fluctuation triggers the actuators, causing the headlight doors to pop open momentarily before the system stabilizes and closes them back down. Since everything works normally after those few seconds, check that your check valve is installed in the correct direction and inspect all hose connections for any small remaining leaks.
If the check valve were in backwards none of the doors would work ever, they wouldn't have any access to vacuum at all.