Automatic Headlight Function

Rog Man · May 23, 2009

I have a Canadian 2006 GMC 2500HD 6 litre gas 4x4 automatic.

My headlight switch does not have an off position. It stops at the stupid auto function and I hate it.

Is there an easy way to kill/disable the automatic headlight function without affecting the operation of the DRL's

Any help would be greatly appreciated?

bill190 · May 23, 2009

Start reading at post number 8 on the following...

http://www.gm-trucks.com/forums/index.php?showtopic=81940

Rog Man · May 23, 2009

Looks like i am outah luck having a Canadian truck, Although i do not want to disable the DRL's just the auto headlights.

I disagree with the statement made there that is illegal to disable auto headlights in Canada as not all vehicles even have that feature?

I guess I will have too dig deeper and see about killing the auto headlights without affecting the DRL's?

Thanx for the link though.

cheers

Rog Man · May 23, 2009

What I need to know is how do I fool the stupid little sensor on the dash into thinking it is ALWAYS bright and sunny outside?

That would achieve the end result that I desire?

superjim · May 23, 2009

What I need to know is how do I fool the stupid little sensor on the dash into thinking it is ALWAYS bright and sunny outside?
That would achieve the end result that I desire?

Just off the top of my head...

I know that the sensor is a photocell, thus it sends varying voltages to the headlight relay depending on light conditions and turning on and off the auto headlights as needed.

You would need to find out the voltage it sends for bright sunlight and then tie into a voltage source with the correct voltage, maybe even disconnecting the sensor.

Then the relay would always think it was bright and sunny and never turn on the auto headlights.

Rog Man · May 23, 2009

I tried covering and disconnecting it, it thinks it is night time then.

I have too find out like you said what it does on a bright sunny day and then duplicate it.

superjim · May 23, 2009

I tried covering and disconnecting it, it thinks it is night time then.
I have too find out like you said what it does on a bright sunny day and then duplicate it.

You are right.

Covering it...it thinks it is night and turns on the lights.

Disconnecting it...it defaults to FAIL SAFE MODE and turns on the lights.

The only thing I can think of, is to find the wires coming from the sensor...measure the voltage it is sending to the relay during bright sunlight...disconnect the sensor and duplicate THAT VOLTAGE going to the relay.

That would keep the relay in the OFF mode.

Then when you disconnect the sensor, the lights will never come on unless you turn them on.