Question: Headlamp switch operation: 1990 C4

[AV8R]

For those of you that have a 1990 or 1991 C4, help me to understand with what Im seeing going on with the headlamp rotary switch.

In my case, I have to turn the lights rotary switch from its lights off (full CCW) position, to the lights on position (two clicks CW from the off position);
which is obvious and what is expected, but...

I have to rotate back to the off position and then back to the on position a second time before the headlamps come up. Does this every time flawlessly.
If I only rotate from off to on state once, the headlamps dont come up. Head lamps go down with just a CCW return to the off position, every time too.

The fog lamp and courtesy light slide switches work. So I dont know if this is correct operation or if there is a problem with the switch or elsewhere.
The switch appears to be smooth, tight, and has the proper detents for each of the 3 positions. No visible damage and each position does it job otherwise.
This isnt a show stopper, because the headlights do work; but I just dont understand why I have to rotate through the positions twice to get the lamps up.

So the questions are:
a. Is this "normal" that I have to rotate the lights switch twice to have the head lights come up?
b. If it is normal, what or why does it operate like this?
c. If its not normal, what are some possible reasons for this?
Like I said, it works fine every time. Just have to do this twice.

Thank you,

AV8R

 

[boomdriver]

For those of you that have a 1990 or 1991 C4, help me to understand with what Im seeing going on with the headlamp rotary switch.

In my case, I have to turn the lights rotary switch from its lights off (full CCW) position, to the lights on position (two clicks CW from the off position);
which is obvious and what is expected, but...

I have to rotate back to the off position and then back to the on position a second time before the headlamps come up. Does this every time flawlessly.
If I only rotate from off to on state once, the headlamps dont come up. Head lamps go down with just a CCW return to the off position, every time too.

The fog lamp and courtesy light slide switches work. So I dont know if this is correct operation or if there is a problem with the switch or elsewhere.
The switch appears to be smooth, tight, and has the proper detents for each of the 3 positions. No visible damage and each position does it job otherwise.
This isnt a show stopper, because the headlights do work; but I just dont understand why I have to rotate through the positions twice to get the lamps up.

So the questions are:
a. Is this "normal" that I have to rotate the lights switch twice to have the head lights come up?
b. If it is normal, what or why does it operate like this?
c. If its not normal, what are some possible reasons for this?
Like I said, it works fine every time. Just have to do this twice.

Thank you,

AV8R

I think it is normal. Designed to help prevent accidental "pop-ups" causing accellerated wear on the headlite motors. The worst thing that happens to the motors is being reversed while in motion. Thats exactly how people react to an accidental pop-up.

 

[AV8R]

I think it is normal. Designed to help prevent accidental "pop-ups" causing accellerated wear on the headlite motors. The worst thing that happens to the motors is being reversed while in motion. Thats exactly how people react to an accidental pop-up.

BoomDriver,

OK ill go with that. Didnt know GM would ever care about things breaking as its more revenue for their parts sales. Being that the headlamp motor has plastic gears and bushings, I guess the scenario you paint would be detrimental to these parts. The quick change in direction would create alot of stress on the parts.

So, no error - no foul. The double rotation of the light switch is "normal".

Thanks

 

[boomdriver]

I could be wrong....but seems like that was the explanation that I got some yrs back when somebody else had the same question. I'm working from memory here...
I've been told of various means to reduce the stress on the pop-up headlites. Why metal gears were not used instead of the nylon and why they were pretty much all plastic (weight). It was supposedly a priority since those along with the round tail lights were the trademark of the Corvette and previous generations of vacuum actuated and other mechanical designs had proven to be even less reliable.

hated to see them go in the latest generation, but everything has to evolve I guess.

 

[DTK90]

90 Headlight Switch

I'm a month late to the party here, but for what it's worth, I've owned my 90 since November of 1989 and it's always been one-click-only. Turn 'em on, they pop up and on. I can't imagine why they would've modified the design. I've never had a problem with mine in 21+ years of operation. (Wish I could hazard a guess as to why yours are operating that way.)

 

[AV8R]

DTK90,

Boomer's explanation is so logical and convincing I just bought it hook line and sinker, plus hes usually spot on in his responses. Now youre being in Lost Angeles (50 miles from me), I have to accept your facts too. Is it possible both are right?

I read that Canadian built vettes are different from USA ones w/r/t the headlamp operation. Apparently Canadian vette's headlamps are automatically controlled. Could the switch operation be related to this? I guess Id also need to know where we read on the vette where it was made or what regulations it was built to satisfy (US or Canada).

See the reference below for a device that defeats the auto headlamp sensor issue:
The Corvette GadgetMan: All

 

[DTK90]

AV8R:

Thanks for the link. Live 'n learn. Had never heard of the Canadian automatic sensor system. (Sounds pretty annoying.) Maybe your "symptoms" have something to do with that.

 

[G Winter]

I have a 90. Turn switch two clicks to headlights, they come on and pop up.
Turn one click back the lights go out but stay popped up. At this point you have park lights
and or fog lights if the fog light is pushed.
To make the lights go back down you have to go to full off.
Turn switch one click to the park lights and you can turn on the fog lights. Which btw only work on dim.
The headlights do not pop up in the park/fog light position.


Glenn

 

[John Robinson]

There is the possibility that at some point during the model year GM had a supplier who could not provide a part because of a manufacturing problem. So GM went to the parts bin to solve the problem with a switch from another model for a short period. I recall when the hydromatic plant had a fire and GM was using the powerglide from Chevy in Pontiac - Oldsmobile - Buick and even Cadillacs.

On my 93 when I turn the wipers on for the delayed wipers it comes on with continuous wiper operation. I have to go one small click further to get the delayed function to work. This has been this way since I got the car and I have accepted the position of IF IT AIN'T BROKE DON'T FIX IT.

 

[Fast Freddie]

my 91 is fully ccw = off and fully cw = on with lights up.... no double operation.

 

[boomdriver]

I know the Ford sensor system works like this...1st turn on 1 click is parking 2nd click is sensor headlites. There is a 2nd knob/wheell to adjust sensor sensitivity IIRC.
To Force headlites back up and rotate to full on a 2nd time if the sensor does not open or turn on.
I forget who has which system...but I do know that they exist in the Vettes as well as other makes and models.