Ford Mustang Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
this is the story:
Yesterday, while at work, I went out to my car on break. When I sat down I noticed the battery warning light was on and I hadn't even put my key in yet. The light was just on. I figured it was telling me my battery power was low, so I started my car up. It was a little sluggish, but it started and I let it run for about 20 minutes, and the battery light went off as soon as it started up.
I went out again about 2 hours later and noticed the battery light on again. I tried to start the car, but this time the battery was pretty much dead (not enough power to start the car). After work I had a friend come by and jump my car, and I drove it home, parked it, and waited. After about an hour, it was dead again.
I replaced the battery, thinking maybe it was just bad, but the battery warning light goes on every time i turn off the car. And if the car sits for more than an hour the battery dies.
While the car is running, I have no problems, and the amps are the same as always. I thought maybe there was a problem with my alternator, but I just replaced it about a year ago, and I never had problems like this before that.
Someone please help me, I really don't know where to begin.
By the way, its a '90 GT.
Joe
:confused:
 

·
Registered
Joined
·
2,121 Posts
Replace the Alternator.

Alternators have diodes in them to prevent the battery from discharging when your car is off. If the diaode is bad, your battery drains through the alternator.
 

·
Registered
Joined
·
665 Posts
Check the connection on the alternator..

When the car is running, what does it say it is putting out volt wise..
 

·
Registered
Joined
·
2,121 Posts
If I diode is bad, it wont matter what the voltage says on the alternator. It will Run FINE and charge the battery when its running. When you turn the car off, the alternator will just drain the battery.

I've had this problem before and the fix was a change of the alternator.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
thanks guys i'll try this first
Joe
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #6 ·
ok guys, the alternator was bad, but I replaced it and the light is still on. My friends father thinks its probably a short somewhere, but I dont have the slightest clue where to begin with that.
 

·
Registered
Joined
·
2,121 Posts
Unplug the Voltage regulator on your alternator (Its the black plug with a clip near the top of the alternator. Plugs into a plast plug).

If your light goes out when you unplug this, remove the alternator, and return it and get a new one.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #8 ·
Dac said:
Unplug the Voltage regulator on your alternator (Its the black plug with a clip near the top of the alternator. Plugs into a plast plug).

If your light goes out when you unplug this, remove the alternator, and return it and get a new one.
tried that when i replaced the alternator. the light did not go out.
 
1 - 8 of 8 Posts
Top