Climate Control Lights dim when braking - Toyota 4Runner Forum

Reidabook · 09-13-2024, 05:50 PM

I have a weird issue in my 4runner. When I push on the brake pedal the lights in the digital climate control switch from the bright mode to the dim night mode. The actual switch on the stalk is in off position. When it's in the middle or forward position the lights stay in the dim mode like they should. It only seems to happen on the climate control, the clock functions normally. I don't have leds bulbs in the climate control just the regular bulbs or led taillights, I know those sometimes do weird electrical things. Anyone else had this problem or know what might cause this?

Reinout · 09-13-2024, 05:58 PM

Quote:

Originally Posted by Reidabook

I have a weird issue in my 4runner. When I push on the brake pedal the lights in the digital climate control switch from the bright mode to the dim night mode. The actual switch on the stalk is in off position. When it's in the middle or forward position the lights stay in the dim mode like they should. It only seems to happen on the climate control, the clock functions normally. I don't have leds bulbs in the climate control just the regular bulbs or led taillights, I know those sometimes do weird electrical things. Anyone else had this problem or know what might cause this?

I'd start by checking the battery and alternator. If, for some reason, the battery/alternator are just bbbbarely providing enough power, it might cause one system to draw from the rest.

If you were to say, turn on the headlights, do you get the same results?

phattyduck · 09-16-2024, 12:22 PM

Step 1, check the grounds in the back and unplug any trailer wiring converters (the OEM one goes bad at this age, so remove it to eliminate the risk during debug). Grounds inside below where the tail light wiring enters the cab.

You will also want to check if the corner lights or cluster lights come on at all. With a helper, check all the other lighting, etc. around the truck at night to make sure it is doing exactly what you expect.

There is also a risk that there could be a broken trace on the flex PCB on the back of the gauge cluster, which can link systems that otherwise seem totally disconnected.

-Charlie

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