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Join Date: Dec 1969
Location: Las Vegas, NV USA
Posts: 69
Altenator Light

Another quick question on behalf of my brother. When he applies the brakes, his alternator light comes on very dimly. What does this indicate?
Old 08-02-1998, 07:43 PM
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Dave at Pelican Parts's Avatar
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It indicates one of about a zillion things, unfortunately.

First, if the light comes on BRIGHT when he hits his brakes, it means there's a real problem somewhere--possibly with his charging system, possibly with his brake-light circuit (and that includes ALL grounds, too!).

Check to see if the light comes on when he uses his turn-signal, his backup lights, and/or his headlights. If the light does come on for these, then the problem isn't in the brake light circuit.

If the light glows dimly with the brake lights on, and brighter with each load placed on the electrical system (all those lights I listed), this may only be a minor problem.

Dig out a voltmeter and check the voltage across the battery TERMINALS THEMSELVES (not the clamps, not the wires, the things poking out of the battery). When the engine is running, you should see 13.0-14.5 volts. Grab the throttle lever and pull, the voltage should stay relatively steady.

Now turn on all the lights you can--headlights, foglights, turn signal, put a brick on the brake pedal. Measure the voltage again. Chances are, you'll now see less than 13V. Pull the throttle lever again so that the motor is running about 2000 RPM. If the voltage stays below 13V, you have a charging system problem. Most likely the alternator is worn out, but it's worth checking all the connections and grounds first.

If the battery voltage goes up to 13.5V or so by 2000-2500 RPM, then your car is just like mine. I'm not satisfied that mine is "right", but at least it doesn't let the battery go dead. I'm told that I may be able to fix the alternator light coming on by cleaning up all of my fuses. I'll give it a try sometime and let you know if/how it works. But don't hold your breath, I haven't gotten around to it yet in the past two years...

Old 08-05-1998, 03:22 PM
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John Rogers's Avatar
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,206
This may sound silly, but it happened to us and I saw it on the Renegade 914 site too, ie: a blown fuse! Turned out it was the 4th one from the right. Along with the red light, the voltmeter in the console would go to 0 when we hit the brakes and the most it would read was about 8 volts!!!
Old 08-05-1998, 06:25 PM
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