I have a Toyota MR2. I installed keyless entry by soldering into the power lock/unlock wires and the constant 12V wire. All good. I then tried installing LED lights by using T taps on door trigger wire and the same 12V. I blew one fuse multiple times doing so, causing me to lose power to various electronics including the instrument gauges. I gave up on the idea.

Around this time, the battery light started flickering. Then it got worse. I would lose power while driving, dash lights would flash (mainly battery, P/S, ABS), no power steering, can't use lights, gauges dying etc.

Replaced alternator, belt and battery.

Issue persists but in an odd way. Car will be fine but if I brake "too much", it will resurface. Or sometimes when I push in the clutch. After driving for a bit, the issue will correct itself. Repeat.

I am guessing I shorted something somewhere? But then problem should be constant. I am stumped.

  • I take it you had the battery still connected while you were soldering things? Commented Oct 3, 2019 at 19:08
  • No, not when soldering but yes when doing t-taps.
    – findwindow
    Commented Oct 3, 2019 at 19:19
  • Start backing things out ... you'll find out what you did wrong soon enough. Commented Oct 3, 2019 at 19:25
  • 1
    Computer wouldn't usually cause you to burn fuses. The thing is, if everything was working before you did whatever you did, and it isn't now, whatever you've done is suspect. Only until you remove things will you figure out what's causing it. Commented Oct 3, 2019 at 20:16
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    Until you remove all the other stuff you did or added, as @Paulster2 suggests, you don't know it's the computer. It might be something else. Commented Oct 3, 2019 at 21:14

1 Answer 1


Too new to comment, so here is my take.

After you installed the keyless entry, did you try that before trying to add the LEDs?

If you did and had no problems, I suspect something with the T taps. If you didn't test the keyless entry before adding the T taps, it could be either new thing affecting your car. You can try to cut out the T taps and splice the wires together (not sure if they penetrate the insulation or not) or remove them. That may have caused the problems. If you remove them and still have problems, look back to the soldering in of the keyless entry. It doesn't sound like you hurt the computer because the fuses did in fact blow, which they are supposed to do to protect the other electronics.

  • Yes, had keyless for weeks before trying LED. The t-tap cutting the wire is a definite possibility. Fuse is not 100% fail proof. You can still fry wiring harness/electronics without blowing them. The reason I believe it's computer is because the problem happens when I brake. If it's wiring alone, problem should be constant. There's a trigger.
    – findwindow
    Commented Oct 3, 2019 at 21:59

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