Listers,
I could use some help with an ammeter problem--it's been driving me nuts for
months! The (new) alternator in my TR6 puts out about 16 volts at 3000
engine rpm. The manual states 14-14.4V should be seen on the output
terminal. This sounds like a regulator problem?
My ammeter jumps around erratically when I drive, all the time. I have done
some debugging, including removing all fuses (thus isolating the
ignition/charge circuit) and the problem persists. I'm guessing that my
regulator is bad, allowing voltage to increase until a cutoff is reached
around 16V, then drops to zero, and starts repeats this rapidly. However,
I've sent the alternator to the remanufacturer, they tested is "for several
hours" and claim it looks OK.
Here's what happens:
1) Start car. Idle at 800 rpm. Everything seems normal.
Ammeter needle steady.
IGN light on.
Alternator + terminal = 12.5 volts (presumably battery voltage).
Alternator IND terminal = 2 volts steady.
2) Rev engine up to 1500 rpm.
Ammeter needle bounces up high on +C side of guage, then down to center, at
about 2Hz.
IGN light flashes on and off, at about 2Hz (on when ammeter needle at
center).
Alternator + terminal = bounces between 12V and ~15V at about 2Hz
Alternator IND terminal = bounces between 2V and ~15V at about 2Hz
3) Increase engine speed to 3000 rpm.
Ammeter needle bounces around very quickly.
IGN light off.
Alternator + terminal = 16V
Alternator IND terminal = 16V (on cheap voltmeter I can't see fast voltage
variations, IE bouncing down to 2V)
Seems that the alternator voltage increases with engine rpm, then something
causes it to switch off and not charge. It then increases again, and cuts
off when it exceeds a certain voltage, and so on.
Any ideas greatly appreciated! Thanks in advance for any insights.
Steve
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