2004 LeSabre: How do I disable automatic headlights?

[Audire]

This is my first car with automatic headlights, and I find them quite annoying. My dash instruments go dim and I cannot shut off the lights until the light sensor gets direct sunlight. How can I make it so that my headlights can be controlled only by the stock switches? Does something need to be done to the light sensor on the dashboard?

[dpalomaki]

Try setting the Twilight Sentinel switch to the OFF position (all the way down). The Day Time Running Lights should still be operational, but rain activated head lights should be disabled as well.

The Twilight sentinel is intended to have about a 20 second delay in responding to sun sensor changes. Starting the car in a garage will often fool the system into thinking its twilight time (without the Platters) so you start out with the dim dash lights.

[Audire]

On my car, the Twilight Sentinel has a spring-loaded "OFF" position, and pressing it does not turn off the lights. I don't mind the twilight delay feature, but all that I really want is absolute control (muuhuuhuuaaaahh!) over my lights. I want them to come on when I press the headlight button and go off when I press it again, and no automatic light-sensing. I believe that I am both intelligent and courteous enough to know when headlights are appropriate, and I don't care for machines making that decision for me.

[dpalomaki]

Originally Posted by Audire

On my car, the Twilight Sentinel has a spring-loaded "OFF" position, and pressing it does not turn off the lights. I don't mind the twilight delay feature, but all that I really want is absolute control (muuhuuhuuaaaahh!) over my lights. I want them to come on when I press the headlight button and go off when I press it again, and no automatic light-sensing. I believe that I am both intelligent and courteous enough to know when headlights are appropriate, and I don't care for machines making that decision for me.

The off position is intended to disable the automatic sentinel operation, not turn off the lights. Section 3 of the owners manual should cover the workings of that system in more detail.

No simple way to fully disable it for 100% assured manual control. Would require some technician ability and time with the FSM to figure out how to modify the circuits and install an appropriate switch. And might negate any potential insurance savings for DRL if not done correctly.

I suspect the real issue is that the LeSabre was not targeted for a market segment that strongly objects to the way the sentinel works. As it stands it is probably a selling point for many (but not all) owners.

[Audire]

I read somewhere that by shorting across the leads of the photocell inside the dome of the light sensor on the dash, the computer would sense that it was detecting bright daylight and would thus override the system. I have some background experience with electronics, and I have doubts about whether the photocell would drop to 0 Ω in direct sunlight, or whether the circuit would tolerate zero resistance. Overriding automatic control of the headlights should not affect the DRL's, which simply go on or off opposite the headights.

[imidazol97]

Originally Posted by Audire

My dash instruments go dim and I cannot shut off the lights until the light sensor gets direct sunlight.

Just turn the slider for the dash light brightness all the way to bright.

[Audire]

Originally Posted by imidazol97

Just turn the slider for the dash light brightness all the way to bright.

Turning on the dome lights, which aren't bright enough to affect the light sensor, is not an answer to my question. I already keep the instrument lights at the maximum setting, which still dims the fluorescent displays so as to be not daylight-readable.

I need the headlights to be solely under my control.

[dpalomaki]

The sun load sensor (photo cell) is actually two photocells, one for the left and right. With the automatic HVAC system they read the sun load and adjust the air delivery (hot and cold deck mix) to compensate for sun load on each side of the car; e.g., more sun on the passenger side means a bit cooler air delivery on that side. If you kill the photocells the system goes into a default setting which means less sun load compensation. Feeding the automatic lights is a secondary function of the sensors - the signal comes from the automatic HVAC control module.

If you want to change the sun load sensor to believe it is always daylight - I would monitor its resistance until it trips to the "wow, its daylight" value, and shunt it with that value resistor. You should still get some benefit of the automatic HVAC sun load bias, not set a DTC code in the HVAC diagnostics system, and it will not likely mess with the dash light levels.

The easiest way to get to the sun load sensor is to pop out the defr0oster grill, you can pry it out.

Bleieve that the DRLs also depend on whether or not the car is in gear.

The trick is to not be one of the many forgetful folks who drive down the road at twilight in ignorant bliss that their lights are off in a car that is hard to see. (And that age does sneak up on all of us LeSabre owners.)

[Audire]

Thanks for the information on the sun load sensor. It sounds like a large can of worms that I'd rather not open. Perhaps I'll just install a separate switch to the new lighting relay. I'll mount it on the dash next to the switch for the LED rear fog light I just installed in the ready-made reflector above the left-hand reverse light.

Originally Posted by dpalomaki

The trick is to not be one of the many forgetful folks who drive down the road at twilight in ignorant bliss that their lights are off in a car that is hard to see. (And that age does sneak up on all of us LeSabre owners.)

I am 38 years old, a former (and mostlikely future) owner of products by the good people at Audi and Volkswagen, where the engineers assume that the driver has at least some degree of competency. Why did I buy the Buick? I got a great offer, I needed a car immediately, and they have a good track record for reliability. Compared with my mother's old '86 Cadillac, this Buick is a Formula 1 racer.

[dpalomaki]

At 38 you are no doubt substantially younger than the average LeSabre owner.

Be aware that most of the stuff in the car is controlled by one or more of the several internal computers. The switches provide an input to a computer that controls the devices directly or via relay if a high current such as the headlights or A/C clutch. The computer systems also provide diagnostic capabilities that monitor the state of the car. Thus, when adding a non-standard control capability it is a good idea to check for possible unwanted interaction with the installed systems.

[maxwedge]

The running lites are not meant to replace forgetful, "old folks" not turning them on, they are for safety issues as a car with the lites on is more visible in the daytime.. I may not agree with the idea of not controlling them, but it can make the car safer. BTW this all started in Canada.

[Audire]

Originally Posted by maxwedge

BTW this all started in Canada.

Yes, and the Canadians got the idea of mandatory DRL laws from Scandinavian countries where sunlight hours are very short in the winter. My issue, however, is with the automatic operation of the main beams, not the DRL's.