headlight switch timing
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Teching In
Joined: Sep 2015
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From: Dunedin FL
headlight switch timing Can the delay on the headlight switch on module be adjusted from about 10 seconds to about 20 seconds after entering the dark garage or tunnel? It's a 2000 model.
Joined: Nov 2003
Posts: 11,329
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From: Jacksonville, FL (originally from Toronto Canada)
Sorry, no it can't.
The timing is a built-in factor of the system that is not adjustable. Even the amount of light needed to trigger the automatic headlights is predetermined by the factory although you can adjust that by adding a resistor either in series (lights turn on in brighter ambient light than factory) or parallel (lights don't turn on until darker than factory setting) with the photosensor in the dash.
The timing is a built-in factor of the system that is not adjustable. Even the amount of light needed to trigger the automatic headlights is predetermined by the factory although you can adjust that by adding a resistor either in series (lights turn on in brighter ambient light than factory) or parallel (lights don't turn on until darker than factory setting) with the photosensor in the dash.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The automatic headlights turn off when there is low resistance through the photosensor and on with higher resistance. That's why the simplest way to disable automatic headlights is to short the two sensor wires together... zero resistance makes the system think it's bright daylight all the time so the headlights never turn on automatically. Unfortunately, I've never been able to find any documentation on the actual resistance value that is the trigger point.
Circuits with resistors in parallel will always have a total resistance that is less than that of any of the individual resistors. So any resistor you install in parallel across the photosensor wires will cause the headlights not to turn on until it is darker outside than the factory setting. But if you use a resistor with too low resistance, the headlights might never come on automatically because the total resistance would be low enough to fool the system into thinking it's still light outside.
If you only want to change the sensitivity slightly then you'll have to use a resistor that has much higher resistance - more than that of the photosensor in complete darkness. You could measure the photosensor resistance in darkness and then work from there but I would suggest using a potentiometer or rheostat would be much easier. Wire it across the sensor wires and then adjust it up and down until you find a setting that turns the lights on and off the way you want.
Circuits with resistors in parallel will always have a total resistance that is less than that of any of the individual resistors. So any resistor you install in parallel across the photosensor wires will cause the headlights not to turn on until it is darker outside than the factory setting. But if you use a resistor with too low resistance, the headlights might never come on automatically because the total resistance would be low enough to fool the system into thinking it's still light outside.
If you only want to change the sensitivity slightly then you'll have to use a resistor that has much higher resistance - more than that of the photosensor in complete darkness. You could measure the photosensor resistance in darkness and then work from there but I would suggest using a potentiometer or rheostat would be much easier. Wire it across the sensor wires and then adjust it up and down until you find a setting that turns the lights on and off the way you want.
