I wanted (actually the wife casually mentioned that it would be nice one day - project authorized!) automatic headlights like on the limited and did some searching in the forums. I found this thread about DRLs that also included a couple of posts (here and here) where Rando described installing automatic headlights. Rando really paved the way but here is my version; all in one place for easy reference.

I think if you have a local pick and pull, you can get some of the parts much more cheaply used, especially the light sensor which was used in tons of Toyota and Lexus vehicles.

PARTS

Limited Headlight Dimmer OEM: 84140-35150 $109

a. Aftermarket – Standard Motor CBS1240
b. Airtex/Wells - 1S3999
(note: There are lots of similar ones for Limiteds on eBay but they don’t have the automatic headlight switch. Check the aftermarket part numbers. RockAuto had the cheapest ones.)

Light Sensor OEM: 89121-12010 $133 (got mine for $99 used on ebay)
Wire Harness
If you have standard climate control you need: OEM 82142-35020 $10
If you have dual climate control you need: OEM 82142-35030 $10 (thanks ThreeFiveO)

Note: As you’ll see in the install, I got the wrong three-wire dual climate control harness which required some minor modification for my ’04. No splicing required if you buy the correct wiring harness for you vehicle.

red butt connectors (X2) (but only if you get the wrong part )

TOOLS

Phillips screwdriver or 10mm socket
Butt connector Crimper
Wire Stripper

TIME

No more than two hours

Once you complete this mod, the tremendous burden of determining if it is dark enough and then removing your arm from the steering wheel to turn that little switch will be removed from your life. You do have to double check the switch if you ever valet park your car or you might end up like this poor woman.

When in auto, the green headlight indicator is only illuminated when the headlights are turned on by the system. There's a two or three second delay before the sensor turns on the headlights when the sensor goes from daylight to dark presumable to keep the headlights from flashing every time you're in a shadow.

STEP BY STEP

• Assemble the parts.
• Remove the plastic covering the instrument cluster. It just pulls off. Helps a bit if you pull out the top of the lower cover but you don’t have to unscrew the bottom screws.
• Remove the speedo cluster. 3 screws plus the 2 screws that hold the wiring connectors to the back of the cluster.

(cont.)

Attached Images