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Canadians - Autoheadlight defeat

Newfydad

Member
Joined
Jun 29, 2008
Messages
23
Location
BC Canada
Corvette
1992 Black Rose LT1-ZF6
I really enjoy my new '92 coupe but one of the things that annoyed me was the automatic headlight feature which turned on the headlights when in my garage and in other places and times when I didn't necessarily want the headlights on. I knew there had to be a way to defeat it, but I couldn't find a definitive answer on the forums - just a lot of confusion between Daytime Running Lights (which are required in Canada but not throughout the USA) and automatic headlights which apparently are a 'feature' on Canadian (but not on USA) Corvettes of that vintage.

A few tests revealed that the ambient light sensor on the dash is simply a photoresistor that exhibits a very high resistance when shielded from light and measures something in the neighborhood of 1000 ohms when exposed to a fairly bright flashlight.

The obvious way to prevent the uncontrolled deployment of the headlights was to fool the system into thinking it is always bright daylight. That is done by soldering a 1000 ohm resistor (the exact value isnt critical) across the terminals of the light sensor. The headlights still turn on with the switch and everything else, including the Daytime Running Lights, functions normally. The mod is easily reversible by simply removing the resistor.
Here is a quick how-to:

1. Locate the light sensor assembly on top of the dash, directly in front of the steering wheel. It looks like a disk about the size of a Loonie. With a small flat-blade screwdriver pry the assembly out of the dash and pull it toward you. There should be 6 or 8 inches of loose wire to play with. Remove the sensor socket from the outer holder by giving it about 1/8 twist. Again with a small flat-blade screwdriver pry the sensor out of its socket so it cant be damaged by the heat of soldering.
View attachment 17472
View attachment 17473
View attachment 17474

2. Strip the insulation from a small section of each wire at the base of the sensor socket. Then solder a 1000 ohm (approx) resistor across the wires. Wrap the exposed resistor and wires with electrical tape.

View attachment 17475
View attachment 17476


3. Insert the sensor into its socket. (At this point the sensor really isnt necessary but its a good place to keep it where it wont get lost in case you ever decide to restore the auto-headlight feature). Twist the sensor socket into the outer holder and then install the entire assembly into the hole in the top of the dash. The whole procedure only takes 10 minutes from start to finish.

As an added bonus, if you just re-install the socket without the sensor, there is adequate room to fish a small power wire through there to neaten up your radar detector installation. :)

Next project: Defeat that annoying forced 1-4 shift on the 6-speed. Thats another 'feature' I can do without.
 
K

kenmack

Guest
easier

Just disconnect the wires from the sensor and connect the two wires together.
Problem solved:beer
 

Newfydad

Member
Joined
Jun 29, 2008
Messages
23
Location
BC Canada
Corvette
1992 Black Rose LT1-ZF6
Being an electronic tech, I tend to shy away from creating direct short circuits on the inputs or outputs of those expensive computer modules when I'm not certain what effect it would have. If you can get away with it - great! - saves searching around for a resistor.
 

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