Gauge backlighting stopped working after installing LED brake and tail lights

Tiny
DAVID VINES
  • MEMBER
  • 2001 TOYOTA TUNDRA
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 236,000 MILES
After installing LEDs in the brake/tail lights on my truck, I have lost all gauge cluster backlighting. All fuses are working, all bulbs are are fine. I'm getting power to the gauge instruments as the speedometer, tachometer and all gauges work, just no lighting. I've seen that for some reason the gauge lights and tail lights work in sync for some reason. Could the LEDS be throwing the computer off to not allow the gauge lights to work?
Saturday, April 10th, 2021 AT 11:04 AM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Short answer is yes they could. The reason is, LED lights have very little load/resistance so they require very little current to run. When the computer does not see the proper returns in voltage it causes the module to do crazy things because it was never programmed to run with those lights.

The way to test this is to just unplug the LEDs and see if the dash lights come back. You can plug the original bulbs in if you want but the dash should come back once they are unplugged if they are causing the issue.

If that is the case then you will need to find out if the LEDs that you installed have built in resistors. Basically these LED light companies have figured this out and include that in the lights so that the system does not realize that there is a different bulb installed. However not all of them do that.

Let me know if you have questions on this. Thanks
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Sunday, April 11th, 2021 AT 8:08 AM

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