Re: 87 t-bird faulty charging system or electrical problem?
> 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 running,
should be ~13.5 volts or better.If not, suspect the voltage regulator. Folks tend to
forget about it. It can be tested, but it's 17 years old and cheap. For ~$15, replace
it and have peace of mind.(Of course check all of the connections first). Then check
the voltage at the battery terminals, engine running, should be ~13.5 volts or better.
If you get less than 13.5 Volts at the terminals, suspect the line between the Alt and
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 misleading
if the voltage is ok under test but the Alt can't produce under load. The main suspect
is the regulator.