I need help please. My 87 thunderbird has a problem. I thought it was the
alternator. had it tested. tested fine. It does not charge the battery in
the car however. the battery is new. it will start and run,but drains the
battery. Also the instrument panel does not work. It lights up, but
doesn't display the information. what's wrong?
First check the voltage at the Alternator output terminal with the engine
should be ~13.5 volts or better.If not, suspect the voltage regulator. Folks
forget about it. It can be tested, but it's 17 years old and cheap. For ~$15,
it and have peace of mind.(Of course check all of the connections first). Then
the voltage at the battery terminals, engine running, should be ~13.5 volts or
If you get less than 13.5 Volts at the terminals, suspect the line between the
battery. If both are low, the "new" battery could be shorted internally, or the
alternator could be defective. Many testers do a voltage test. This can be
if the voltage is ok under test but the Alt can't produce under load. The main
is the regulator.
Digital speedo with fuel gauge, temp gauge, and alternator "idiot" light?
Does the alternator light come on with the key at "on"?
The alternator gets its "start-up" power through that light, or a built-in
if the light happens to burn out. Once running, the alternator is
If the light doesn't come on, the bulb may be burned out, one of the wiring
connectors on the back of the gauge cluster may not be plugged in all the way,
there could be a broken wire somewhere under the dash (anyone been messing
around under there, like cutting wires for a stereo?), or the ignition switch
be faulty. Do the back-up lights work? They get power from the same terminal
on the ignition switch as the alternator light (and several other things).
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