The 2008 RDX Owners' Manual (page 167) states:

The climate control system has two sensors. A sunlight sensor is in the
top of the dashboard, and a temperature sensor is next to the steering column.

Given that the RDX has a SUNLIGHT SENSOR, I'm wondering how possible it might be to find a way to switch low beams on/off based on the sunlight sensor.

I'm finding I really miss the dusk sensing headlamps in my BMW when I drive the RDX. It's nice going through tunnels and driving into the many parking garages in LA.

 

ya id love auto sensing lights.

 

me too.

 

i wouldnt want the auto switching for my HID lights since it causes undue on and off of the lights. HID lights i dont believe are suppose to be turned on and of as in the case would be if connected to a sensor like that. I think its worst for HID's then regular lights.

 

I'll pass your technical expertise along to BMW, Lexus, and the other lux manufacturer's whose systems provide dusk sensors with HID headlamps.

 

turning it on and off yes does wear it out but meh oem hid bulbs are like 100 bucks. Theres a guy that runs his hids every time he gets into his car and changed the bulbs after 3 years as they were going pink I believe.

3 years is fine and dandy.

 

go ahead acurarascal, why you have to follow me around talking shit? so you know, theres some design specs that would be helpful if you were to use a photo sensor, but either way without getting into that you can leave it alone, you can have your opinion too, but just quit trolling to bust on me. Countless sources about turning em on and off is widely known, but being a smart ass is probably what you were going for anyways. now, stfu and let grown ups discuss things, thanks

thats great mau108, in fact, my subaru had them and would turn on also when vehicle was being driven... but thats the point I am saying, leave them on is great, the constant on off though is whats more hurtful. For example driving in a tunnel or covered bridge. But whatever you do your welcome to it, personally I wouldnt want the lights in my rdx running on a photo sensor.

 

I just thought it was funny that this thread is ACURascal's thread to begin with....

 

alright its real funny. but there was a difference when someone posts an opinion and trys to help by informing and then trolls for issues with someone.

but you know what, i tried to give this forum a good go, but cluttered with a very very few people that actually have some knowledge of cars is the mass ignorance of yellow racing sticker modders. I mean seriously, is it such a hard understanding to grasp that turning on/off the lights repeatedly is bad for the lighting system? guess so for some/most... so sasair, go ahead and delete my account im gone, i dont need such a rookie pos site that is bent on mods like yellow stickers or bov or even bitching about how customer service really works... wow what a contribution to acura's acurazine provides!

 

hahahaha this guy is hilarious

 

ACURascal posted a very valid point to respond to your post. I don't see how he is "trolling to bust on you". You two have only posted in a few of the same threads. You're gonna have to have much thicker skin to survive any internet forum. This RDX forum is one of the most tame out there. I've said it before and I'll say it again. If you are going to post on any forum, be ready for someone to refute it, right or wrong. I'm not even sure what you are talking about with your "yellow stickers" comment. Good luck finding a better RDX site out there!

Back to the topic, I don't see how having an auto lights on and off would be bad for your HID lights. I have them on my G35, and they work great. Yes they do turn on in tunnels and when I enter a parking garage or any other time the light goes dim. That's what they are supposed to do. You should have your lights on in tunnels and garages and anywhere else where the light is low. Safety above all. There may be the rare occurence where it will turn my lights on unnecessarily, but not enough to warrant not having the capability.

 

umm... nevermind.

thanks, anyway, sasair.

 

For what it's worth, the Service Manual schematics show the sunlight sensor feeding info to the Climate Control unit. The Climate Control unit uses sunlight data in conjunction with the GPS provided relative sun position, to determine which side of the cabin should receive more cooling. (After almost a year, I'm somewhat sceptical about how well this works.)

You would have to feed the Sunlight Sensor info to a switching unit for the HIDs, but the manual doesn't make clear if the sunlight data is a graduated signal or a simple on/off. In addition, it probably works something like the Outside Temp Sensor in that it has a preset sampling rate in order to avoid rapid cycling.

Also, in my own experience with VW HIDs functioning as DRLs, the constant cycling and use shortened their sevice life to about 3 years. This may be why Honda uses ordinary H7 bulbs for DRLs and leaves the HIDs off.

 

D2S service life is rated around 3000 hours. That's about 2 years at 4 hours per day, every day. Lasting 3 years would put usage around 2.75 hours per day.

I've not found any credible service bulletin from any manufacturer of D2S / D2R lamps that indicates that service life is shortened by frequent duty cycling. Do you have such a thing?

I suppose the next step would be to examine the sunlight sensor itself -- maybe even buy a spare, power it up, and see how leads perform on voltage/bias differentials. It may be a rather simple device -- or, as you pointed out, it may be rather complex.

 

The 1st gen D1S HIDs in 2004 Touaregs all failed early. When I replaced mine the the new units were a later gen with different part numbers and the igniter base weighed only half as much. So perhaps it is not a fair assumption that DRL cycles contributed to the early failure. (They were Osram/Sylvania).

Nonetheless, DRL use accrues duty hours twice as fast (assuming 50/50 day/night). This may explain why Honda (guarding their reputation for durability) doesn't employ expensive xenons in DRL duty.

I haven't seen a TSB either regarding cycling vs life. Xenon service life is typically shortened by improper application; inadequate cooling space or mounting in wrong position or plane, ie: teenager aftermarket installs.

However, cycling on/off without proper cooling (3 times per hour) is suspected, but not yet proven to shorten life. This would cover DRL use (frequent short drives), although probably not light sensor activation (garages/tunnels).

Since you have to get a switching unit as well, I wonder if you couldn't just buy an aftermarket automatic headlight kit. I imagine many people would be interested in your success with that.

 

I had hoped to use the switcher already available for the auto shutoff and auto on (with door open), since it's clearly already wired into the headlamp controls.

 

After looking at the parts book image, I wonder whether the "sensor" is electronic at all. Either it or the ambient temp sensor (or both?) is/are attached to an "aspiration tube" which suggests that it feeds a temperature gradient to the climate system, which determines whether to adjust the temperature in the cabin.

 

I did a little research.

The sunlight sensor is at the top forward of the dash under the windshield. It is electrical and sends a variable strength signal. Test voltage is 3.0 to 3.5 volts in direct sunlight and 3.6 to 4.0 volts in shade.

The outside temp sensor is in front of the radiator on the lower left. It also sends a variable strength electrical signal. Test resistance is 1k ohm at 40C up to 11.5k ohm at -10C. The outside sensor is not aspirated, so it is subject to heat soak errors when the car is not moving. Because of this it has a preset sampling rate to reduce Climate Control cycling.

The in-car temp sensor is under the driver side lower dash (shown in your diagram). It uses the exact same resistance scale as the outside sensor, but it is aspirated. The aspiration tube (4 in your diagram) runs from the in-car sensor (3) to the blower/mixer box (B-17-20). The blower draws a continuous low flow of cabin air over the sensor so it is never sitting in a pool of heat or cold. Aspirated sensors are very accurate and consistant. (The aspiration air is then just dumped into the mixer box.)

I hope this is helpful!

Your challenge may be to get a useful on/off voltage from the sunlight sensor to the headlight/door switching unit.

 

This is great. My next stop was to have been at the dealer the buy this unit to do exactly what it looks like you've done. So, thanks for the extra work.

I suppose I'll have to bench test this to find out how reliable the hi/lo states are for this sensor. If they prove to be reliable, then it'll be no problem to build a little converter if necessary that will interface with the requirements for the existing headlamp switching system. Otherwise, it may be necessary to look for voltage deltas (hi to low or low to hi) rather than states. There's also the possiblity of just adding a small circuit with a photo diode or resistor to act as a standalone sensor. The problem with this approach is location and aesthetics.