Disable sensor on low beams

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Dec 18, 2006 | 2:22 AM

#21

73shark

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Joined: Apr 2006

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From: KC, MO area

RE: Disable sensor on low beams

My suspicion would be that it is a phototransistor or diode that is biased to provide a signal to the computer that is interpreted as nite or day. Just a guess tho.

Dec 18, 2006 | 2:54 AM

#22

VKtahoe

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RE: Disable sensor on low beams

I have installed HID lights for my tahoe and I dont undersatnd why you are going to all this trouble to deactivate the automatic lights. They work fine. Please let me know what I'm doing wrong.

Dec 18, 2006 | 11:39 AM

#23

golfer

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RE: Disable sensor on low beams

Quote:

ORIGINAL: ChadS

Golfer, thanks for your input..
This afternoon after I disconnected the sensor and the lights remained on. I started thinking sensor was a variable resistor too... but when I attach my ohmmeter it reads "open-load" (no resistance) in daylight or darkness... the next step I'm thinking about (when it gets sunny again) is attaching it back into the BCM wiring harness and taking a milivoltmeasurement on the white (ambient light sensor "signal") and the gray (ambient light sensor "reference").

Ihave a feeling that the sensor actually outputs a milivolt signal that corresponds into "lumin's" that the BCM (body control module)reads and determines how"light" it is.... Thats the way it works with the ambient light sensorsin commercial buildings (to automatically turn on parking lot lights) or so I've been reading.

If there are only two wires to the sensor it would be a passive device. This means it isn'ta source for providing any kind of signal.Usually a photo sensor is a variable resistor in which case would act as a voltage ( current ) dropping device. The control module would provide the voltage ( current ) to the sensor and the change of that voltage ( current ) back to the module would determine what statethe sensor isin .

If there are three wires to the sensor it would be an active system. it would have power , ground and an output. The output would supply a reference value to the module as to what state the sensor is in.

Dec 18, 2006 | 1:38 PM

#24

jlenkows

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RE: Disable sensor on low beams

Here's a thought.... pull the sensor into the dash and wire up a white LED to turn on when the key is turned. That will trick the sensor into thinking the sun is always out.

Don't laugh - it WILL work.

Dec 19, 2006 | 8:24 PM

#25

Hatchfinder

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RE: Disable sensor on low beams

Have you tried disabling the mechanism in the headlight switch that bouncesthe switch from the off setting (the O symbol) to the AUTO setting? Could be something as simple as a little spring. But then again, it could explode into a million pieces.

Dec 23, 2006 | 11:39 AM

#26

golfer

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RE: Disable sensor on low beams

Quote:

ORIGINAL: 73shark

My suspicion would be that it is a phototransistor or diode that is biased to provide a signal to the computer that is interpreted as nite or day. Just a guess tho.

This could be the case.
In which there would be a small measurable voltageacross the two leads when there is light . It would have to be determined what that value is then constantly in place when the sensor is removed from the circuit. This would mimic the sensor and signaling the BCM it's seeing daylight and not to turn on the headlights.

I had been going on the premise that GM would be using the economical , reliable ,simple ,and proven photo resistor used in most light sensing devices.