headlights open and close randomly
Thread Starter
Heel & Toe
Joined: Feb 2013
Posts: 18
Likes: 0
From: galena mo.
headlights open and close randomly
my headlights pop up and close randomly. the lights don't come on when they do this. the twilight is off. they stay up from 2 seconds to an hour and sometimes they open and close 3 or 4 times in one minute. ive turned the lights on then back off while the door is up and it does nothing. after I turn the car off it takes 1 to 10 minutes before they close. this happens about 80% of the time I drive it. it looks like crap with the doors up and lights off. so I end up driving with the lights on all the time. help please. by the way its a 99 coupe z51 6 speed
Last edited by jon reed; Jun 4, 2015 at 05:55 PM. Reason: added text
Intermediate
Joined: Apr 2014
Posts: 30
Likes: 0
From: Mandeville La
My 99 does the same thing. I'm thinking that the switch is starting to fail to make full contact when turned off. Try putting a little pressure on the switch by twisting off and holding to see if they stay down, mine stays down when I do that. That why I believe it is the switch.
Thread Starter
Heel & Toe
Joined: Feb 2013
Posts: 18
Likes: 0
From: galena mo.
random
My 99 does the same thing. I'm thinking that the switch is starting to fail to make full contact when turned off. Try putting a little pressure on the switch by twisting off and holding to see if they stay down, mine stays down when I do that. That why I believe it is the switch.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
The MF switch is the most probable cause and is a known bad actor. Much less likely that it would be a random action by the BCM or the Headlight Module.
The circuits for the lights and the door motors are separate so that can explain why just the doors actuate and not the lights.
Bullymp's experience supports that.
The circuits for the lights and the door motors are separate so that can explain why just the doors actuate and not the lights.
Bullymp's experience supports that.
Last edited by dadaroo; Jun 6, 2015 at 07:59 AM.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
I don't have the schematics at the moment but I'm pretty sure there is an "off" contact in the headlight switch that feeds either a ground or a power signal to the headlight door motor control module. So, if that contact is failing the module won't get a proper "down" signal from the headlight switch.
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
The MF switch is the most probable cause and is a known bad actor. Much less likely that it would be a random action by the BCM, IPC, or the Headlight Module.
The circuits for the lights and the door motors are separate so that can explain why just the doors actuate and not the lights.
Bullymp's experience supports that.
The circuits for the lights and the door motors are separate so that can explain why just the doors actuate and not the lights.
Bullymp's experience supports that.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
The MF switch provides the ON and OFF input directly to the HL module to open and close the doors under normal (non Twilight Sentinel) use.
When Twilight Sentinel is used then Relay 44 provides the ON input to the HL module just ahead of the MF switch since the MFS is still in the HL OFF position. The OFF input to the HL module is still provided from the MF switch once Relay 44 opens and terminates the ON input to the HL module.
When Twilight Sentinel is used then Relay 44 provides the ON input to the HL module just ahead of the MF switch since the MFS is still in the HL OFF position. The OFF input to the HL module is still provided from the MF switch once Relay 44 opens and terminates the ON input to the HL module.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer