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years ago I messed up my rearview mirror so it could not be repaired and I have been using a generic replacement. I do not like auto-dimming, so I do not miss that but i miss the auto light function. I am wondering if there is just a light sensor I can hook up to the pinouts on the connector to replace that function.
I have started to do a little research, but if anyone has any thoughts to jump-start this that would be great.
Should be easy enough. It's late so working from memory, but as I recall the yellow wire in the mirror harness controls auto on .
A thought: Scott, why not just leave them on all the time for safety and convenience?
If you want on only in the dark, put a light sensor LED in series to control it.
Want a faster answer? Do advanced search on my name. I've posted the wire color several times. I'd do it now but gotta run. As I recall I noted if it was ground on or 12v to turn on auto.
A quick google search on LED light sensor circuit should help you design a sensitivity adjustment for activation.
The headlight sensor is an LDR (Light Dependent Resistor) along with a pot to adjust the sensitivity. You can see it here in this photo from the DVR mirror thread:-
The easiest solution would be to get hold of a scrap mirror from someone and use the PCB from that.
"A thought: Scott, why not just leave them on all the time for safety and convenience?" On the 99 you can't do this, the lights stay on when the car is off, otherwise, I would
"The easiest solution would be to get hold of a scrap mirror from someone and use the PCB from that." that is a good idea, may look into it if i find a junker
I wonder if this would work, I do not understand all the circuit and resistance practices but the diagrams of how people use them should be easy enough to implement when I get the pinout for my system.
Just looked it up. Yellow blue wire does control auto headlight.
Apply Image 1 of 2. See YU (yellow blue) wire to auto on selector. 2 of 2
12v from a switched ignition source, headlight should turn on only when ignition is on. If auto is selected.
"12v from a switched ignition source, headlight should turn on only when the ignition is on. If auto is selected."
I guess to do this you would bypass the light sensor, right? In the "On" mode the lights stay on when the car is off and in the "Auto" mode the lights do not go on. I may give this a try.
"Daytime Running Lights is an option in the IDS/SDD software. There are three settings; Off, European, or North American."
Is this something that can be selected? Does it have to be done at the dealer?
Yes Scott that's right. I've got a Titanium or dark grey colored XK8. This car blends into the asphalt colored roads way too well for me to ignore.
Decided I wanted the low beams on any time I turn the ignition on the day after I almost pulled out in front of a guy with same colored car, lites off, at dusk one evening. Would have been my fault, but whew it was hard to see!
I now place a piece of black tape over the sensor. It thinks it's dark out = my lights are always on.
"Daytime Running Lights is an option in the IDS/SDD software. There are three settings; Off, European, or North American."
Is this something that can be selected? Does it have to be done at the dealer?
Anyone who has access to the required software and cable can do it. A dealer, an independent, or another owner near you. Or you can buy the software and cable for the neighborhood of $100.
An advantage is that this does not require any modifications to the vehicle that you have to remember years from now when trying to track down some gremlin.
Last edited by bakntyme; Jan 26, 2020 at 03:48 AM.
So I bypassed where the sensor would presumably control the on and off. I got the results I wanted with the lights at first, they went on when the car was on and off when I turned it off. There were two issues that made this unworkable.
1. Even though the lights were off when the car was off, when I opened the driver door I got the beeping sound like the lights were on.
2. The dash lights stayed on when the car was off when I did this bypass.
If you want to fix this let us know Scott. I bet it will come down to what source is used for the switched 12volts to YU WIRE, double check which wires are now connected together. And finally reviewing the circuit diagram - maybe we need a diode to prevent reverse current to other legs of the circuit.
build a light sensor for the auto on lights
