87 t-bird faulty charging system or electrical problem? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
 
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post #1 of 4 (permalink) Old 03-31-05, 10:01 PM
wilnbon
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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?

 
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post #2 of 4 (permalink) Old 03-31-05, 11:02 PM
Tom Adkins
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Re: 87 t-bird faulty charging system or electrical problem?

wilnbon wrote:
> 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.
Tom
 
post #3 of 4 (permalink) Old 04-01-05, 11:08 AM
MasterBlaster
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Re: 87 t-bird faulty charging system or electrical problem?


"wilnbon" wrote

> 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?


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 resistor
if the light happens to burn out. Once running, the alternator is self-energizing.

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 may
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).

 
post #4 of 4 (permalink) Old 04-01-05, 05:01 PM
gerald smith@impco.com
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Re: 87 t-bird faulty charging system or electrical problem?

On Thu, 31 Mar 2005 22:48:06 -0500, "wilnbon" <wilnbon@nospam.net>
wrote:

>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?


does your have external regulator ?
 
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