I didn't get the repair terminal part number, but they did have it in the system at the Toyota parts counter. When the parts lady said they were $20 each and special order, I started evaluating other options. It did sound like the standard repair with 6" of wire lead though.

I looked for quite a while trying to find the terminal part numbers with no success - I don't think anyone has figured them out. If your able to find the correct, I would be quite interested.

My suspicion is that the connector is so tiny, fragile and finicky ( I tried taking it apart to inspect the terminal locking mechanism), that Toyota doesn't want you messing with it.

Two more of the pins on the light sensor (1 and 2) if i recal, go to the automatic HVAC if you have it. The last connector is not used.

I'll be home in a few hours. I'll plug the $7 sensor in. (there are wires attached to the blank plug)
If it doesn't work I'm not disassembling my truck. I'll (maybe) monkey with it when I install other lights.
Thank you for the information in this thread.


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Connected the sensor. No difference.
With headlights on, covering or shinining a light on it made no difference.
$7 invested in the future.

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Just did this mod today on my 2016 TEP and it worked beautifully. I spent all of 43 seconds completing the install. Thanks, OP for posting this info!

Make sure your dash light dial isn't in the full max position (past when it clicks).

I tried both positions.
I'll mess with it after work tomorrow.

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Did you check to see if the BCM F9 connector had pins 21-23 populated?

question for ya....

Sorry, need to correct my previous post, pins 20-22 are the ones you need. But yes, the pins you have circled is the area of interest. Specifically the pins you have circled in that picture from the corner are 19, 20 and 21. What you cant see in that picture is pins 22 and 23 which were also empty on mine.

I guess it's possible that I received a defective sensor.

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I came across a document from Toyota on testing the sensor with a multi-meter. I'll try to find it and post a link.

Found it.

If you need to check if your sensor is performing as expected, follow the procedure in this document:
Toyota 4Runner: Light Sensor Circuit Malfunction (B1244) - Lighting System - Service Manual

Attached Images

Toyota 4Runner_ Light Sensor Circuit Malfunction (B1244) - Lighting System - Service Manual.pdf (163.7 KB, 598 views)

Bought the 89121-30020 sensor on eBay. I made on offer and knocked off $6 and he took it. Paid $68.99, free shipping. I have a 2020 ORP. Wire was pretty short, so I tied a shoelace to it before I released the dummy sensor. New sensor plugged right in. Tested and works great before I pushed sensor back in the hole. Love the results. Much better to see when lights are on during the day for bad weather. Thanks to all for the info. Mike

Calling 2 dealers with a PRO Vin
The 2020 part
Ambient light sensor
New number 89121-0E060
89121-30020 succeeds to this new number

I would not buy from the dealer as it seems to run around $130. Search eBay for the old number, not 4Runner. These are a common Lexus part and seem to go for about half of the dealer price for a new one. It took 3 days, over a weekend, to arrive, I took my time, was very careful and it probably took 7 minutes to install and test.

I did a ski trip to Whistler, BC in January and had snow in Vancouver. I had my headlights on in daylight due to the road conditions. It was very hard to see my GPS due to it was too dim. This mod fixes that....