alright so i have been helping a local guy with his 1990 vert. Has about 60,000 miles on it, automatic transmission, very very clean car.

As of a few days ago, the battery seems to be draining on it. He had the alternator checked and it works fine. Gauge was reading 14.4v volts charging anyway. Thinking that perhaps the stuck mast on the antenna was the issue, we unplugged it but this seems to not be the source. Power windows work fine. There really isn't much else that is obvious.

So, what are the most common areas to check for a battery drain with the ignition off?

 

The car could have the factory alarm... that could be on silent alarm or whatever, I dont really know because the alarm in my vert has never worked.

 

you mean preventing it from starting? or draining the battery?

The car cranks real slow if it hasn't been completely drained. Battery is only about a year old as well. I may him check for a dead cell.

 

Check the plug on the back of the alternator. Those wires gets pretty brittle, you might have to follow it into the harmess a few inches.

 

Take your negative battery terminal off the battery, put a multimeter set on amps with one lead on the terminal and one lead on the negative battery post. The normal key off draw is like .002 or .02 cant remember kinda drunk at the moment. But anyways, make sure all the accessorys are off, all the lights are off, and start pulling fuses one at a time. When you pull a fuse and see the draw go way down that is probablly the circuit you are having issues with. Use your wiring diagram to see what all that fuse feeds power to and go from there. Or post on here and we can give you a hand. Make sure your trunk light is going off when you shut the trunk, if the switch is bad the ligth will stay on and kill your battery.

 

all FC's built after the 87 model year had a factory alarm.

 

thats a pretty good idea, ill give that a whirl.

 

Check your energy output cable.

 

Any aftermarket stereo or alarm wiring? Always check the aftermarket stuff first.

 

A test lamp will also work connected between the negative battery post and cable. The light will go out when you pull the fuse with the shorted circuit.