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My 2000 Silverado should have auto lights but mine hasn't since I bought it. Today I noticed that the gray and white wires from the ambient light sensor are jumpered with a switch under the dash near the BCM. With the switch on, is that supposed to force them on or force them off? It didn't work either way today when I tried, but I may have not covered it well enough.
Evan, in my book, I'd say you are blessed. I have been trying to defeat the auto headlights in my 99, and still can't kill'em...
Jumpering the gray & white wires (A4 & A6 on the purple connector) lowers the resistance reading of the ALS & the BCM thinks its always daylight. Switch on = always daylight, no AHL. Switch off (should) = factory AHL.
The thread I followed had a 1.5K resistor in series with the switch so the BCM wouldn't read a short & log an error code. This set-up worked excellent for for three weeks, now, no matter what I do, the lights are on in anything but direct sunlight...
Forgot... to cover the sensor for 'testing', I used the black lid off a spray can of undercoating (or paint). The towel other threads say to use I think may still bleed too much light...
why would you want to get rid of the auto-headlights? That is probably the best simple feature GM has put on these vehicles..
I figured it out. Now I have my auto lights again!
PS. if you want to lose your auto lights, look under the dash below the steering wheel. There is a purple connector going into the BCM and in that connector are a gray and a white wire. They had a switch tapped between the two and that worked to disable them. No problems with the setup.
The 2 reasons I have to disable the AHL is that they don't shut off while cranking to start, and I'd rather have all available amps going to the starter on cold dark winter mornings.
AND... they come on in anything but direct sunlight, so either the sensor or BCM ain't quite right either...
-still working on it.
nice that you figured it out. i purposely killed my auto-lights by using a 1.5kOhm, 1/2W resistor in place of the light sensor.
mine were just overly sensitive & would turn on in anything but direct sunlight... maybe my windows are a bit dark :)
Have you measured the amp load of the headlights? It's a lot more than the glove box light (wait, they do not have those any more) but in ratio (by percentage) it's a whole lot less than the starter, the highest amp draw device in the vehicle.
the final answer... with sensor taken out of the circuit: The 2.2K resistor didn't do it; Lights stayed on. A 1.5K resistor didn't do it either. Lights still on.
I went down to 470 ohms (cause it was the next lower value I had)- out went the lights.
the 5V reference measured 5.12V, and the return was about 3.6V if I remember right (it was 2 weeks ago). No error codes & no more headlights on in bright daylight, wa-hoo!
If the auto headlights are hurting your cold morning start you need a new battery. Bypassing the auto on headlights won't fix a bad battery.