Auto-Dimming Dash Light Mod 5th Gen 4Runner – How To Dim The Lights in Your 4Runner

Auto-Dimming Dash Lighting for 5th Gen 4Runner – Compatible with 2014-2019 5th Gen 4Runner, Not Compatible with 2020+

Sometimes a mod isn’t a way to improve stock capabilities, it’s a way to bring your vehicle up to what should be stock. In this case, that’s unlocking your 4Runner’s ability to do something it’s already built and programmed to do. Certain 5th Gen 4Runners are pre-wired for auto-dimming lighting. Specifically dimming the dash and infotainment touch screen when in a dark environment, or turning the brightness up when you’re in a sunny one. In the case of TRD Pro or Limited models, that’s a feature that’s active as soon as you take delivery of your vehicle.

But for the rest of us, we have to switch between Off or Daytime Running Lights for bright environments and On for dark ones. Not a big deal, but easy enough to fix if you’re willing to roll the dice with international sellers on Amazon or eBay.

Find It Online 

• Auto Light Control Sensor (Toyota part#89121-50020): Check Price

Note that when I ordered my sensor, it shipped from China using China Post. If you don’t have any experience with China Post that means it took a long time, approximately six weeks, from purchase to delivery.

You can of course buy the part directly from Toyota. But doing so will cost you $200 compared to the $10-$15 you can spend if you’re willing to take the gamble on sketchy Chinese sellers on Amazon or eBay. But more on that in a minute.

Tools & Materials

It doesn’t get much easier than this.

• Interior Trim Tool
• Something to clean your windshield afterward (optional)

Check to Make Sure You’re Compatible

A fair bit of research has lead me to believe that the only models pre-wired for this sensor are the SR5 Premium, the TRD Off-Road Premium, TRD Pro, and Limited. In other words, it is models with the upgraded infotainment system, and the Pro and Limited models already have the sensor installed from the factory so they won’t benefit from this mod. So if you have either variety of Premium models, read on.

But if you don’t, it’s easy enough to check by popping off the dash plug and taking a look. Simply slip your trim tool under the blank plug at the center of your dash, and pop it out. If there’s a wire connected to the plug, you’re in the game. If not, better luck next time.

Step 1. Remove Blank Plug

Just like step zero, all you’ve got to do is slip your trim tool in between the blank plug and your dash and use the power of leverage to pop it up. If your 4Runner is pre-wired, the connector will be attached to the plug.

Step 2. Swap on the Sensor & Install

Carefully, so you don’t drop the wire back behind the dash, disconnect the wiring and attach it to your sensor.

Feed the wires into the hole, and pop the Sensor back into the hole. Note: This part of the process appears to be irreversible, so do not “test fit” the sensor before attaching it to the wiring harness.

Testing

That should be it. So start your 4Runner turn on your headlights, and test the sensor by either adding light (with the flashlight on your phone) or blocking it (covering the sensor with your hand). When the sensor detects light, it should brighten both your infotainment screen and your dashboard illumination to the same levels you have when in Daytime Running Lights or Off. When the sensor doesn’t detect light, it will dim both to the settings you previously had for On.

Final Thoughts

The functionality of the sensor is exactly what it’s supposed to be. It’s especially useful if you like your interior extra-dark at night, but still want to have more visible instruments when your headlights are on during heavy rain or snow. Not exactly a game-changing mod, but it’s nice to not have to switch between headlight settings while driving in variable weather. It’s a feature that came stock on my wife’s fifteen-year-old Corolla, but Toyota makes you DIY for a much newer 4Runner. Weird.

So I’m left wondering why I had to do it in the first place. Not that I actually needed to, obviously. But why is Toyota not doing it at the factory? My 4Runner had everything it needed to run this sensor. Toyota even wired a dummy plug so it’s not like they saved the cost of installation. Their $200 parts price is obviously inflated, even if the back-door price on Amazon and eBay is artificially cheap. But in the cost of a $40,000 truck, it seems bizarre that Toyota isn’t willing to throw in the sensor.