Question about 1984 Toyota Celica Supra

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'84 Supra - Alt & Brake warning lights always on

As the subject says, I have an '84 Supra (5M-GE) and the Alternator warning light and the Brake warning light are almost always on. They come on together and go off together. Also, the alternator voltage jumps around occasionally, sometimes jumping up to around 18 volts, but most of the time it sits right where I expect it to be.

I'm assuming that these two items are connected, but wanting to check and see if I'm right before taking it off and getting it replaced. Thing is, the lights are on even if the voltage isn't fluctuating, so that's why I'm a little uncertain. Ideas?


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  • Nick_Wilson Jul 27, 2008

    It *was* the voltage regulator in the alternator (they are integrated, the VR is inside the alternator). I have a lifetime warrantee on it, so cost was no big deal, it was taking it off and putting it back on that I was looking to avoid if unnecessary.

    So for those of you who have both the alternator warning light AND the Brake warning light on, the first place you should be looking is the alternator. Since I saw the same problem posted for a '87 Tercel, I'm assuming that most Toyotas around those years would have the same warning lights for this problem.



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It's possible that the voltage regulator is shot. I don't know whether the regulator is integrated into the alternator on your car, but a Toyota parts counter (call your dealership) can tell you, if you ask them for a new voltage regulator. They'll tell you if it's available separately or if it is part of the alternator.

Posted on Jul 26, 2008


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