So, my Fiero and I have come to a rough point in our relationship. I'm ready to go, but she's not moving. heh - Anyway, I have a brand new battery (1 week old) however, if it gets cold overnight the battery completely drains. I was thinking it could be the alternator, but when I'm driving around everything seems to be fine. I figured I might as well try posting in here just in case there's a Fiero-specific problem pertaining to this situation. Does anyone have any idea why this is happening? Thanks again for your help!

-Rich

Head light motors probably need rebuilding?

Easy way to check is to fully charge up your battery and then disconnect the headlight motor, leave it overnight, try again in the morning. Headlight motor can be disconnected, connector on wire on side of light. You can manually crank the head light up into position if you need to drive at night. Rodney Dickman and also the Fiero Store has rebuilding kits, it's a fairly easy process to rebuild the motors if that is what is causing the drain.

Some folks have reported hearing a click inside of the motor every 20 seconds or so on the motor that needs rebuilding.

You can also use an idiot light or a meter at the fuse box to determine the drain. (heads up, your courtesy lights are wired hot into two different circiuts by GM, that little tidbit will help keep you from going batty trying to figure that one out. ))

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jetman
Silver 86 SE 2M6 4-speed, with "check wallet light"
Now fortified with 8 essential slices of bacon goodness

Or radiator fan relay under the L headlite. That drained my battery dead in 2 hours. Sooo dead in fact it would not jump start or recharge again. If neither of those, use the test light proceedure to find what component is draining it.

Rich,

This exact same thing happened on my SBC kit and it WAS the alternator - or rather the voltage regulator inside the alternator. Doesn't take too much of a draw to take your battery down overnight. This is actually the easiest thing to test....

Unhook your battery and charge it up.
Unhook the wires from the alternator and secure them away from trouble.
Hook your battery back up.
Check to see if it drains overnight.

My car also ran fine while I was trying to figure this out. Voltage read-out was correct too. New alternator fixed it.

If it's not the alternator, then you're going to have to end up pulling all the fuses and putting them back in till you find the circuit causing the issue. (Of course retest with fuses out and alternator disconnected to see if it's outside the fuse box circuit.) I've tried in the past measuing the amp draw from the battery while doing these tests, but I had no luck - so this can take a long time. Perhaps you'll be more fortunate.

Good luck.

[This message has been edited by RTNmsds (edited 10-19-2010).]

Seams like every fiero I have owned has had this problem and it comes down to the BAT fuse and the one right above it I think it is the brake lights fuse. one time it was the starter solenoid and the other alternator.

Listen closely in the console area after you turn the engine off to see if you can hear a hum that lasts for more than a few seconds. If you do it is the fuel pump continuing to run. Most likely cause is the oil pressue sender switch has stuck on. Pull the plug off the sender and see if the hum stops. If it does, replace sender. If it doesn't, replace the fuel pump relay.

[This message has been edited by 2farnorth (edited 10-20-2010).]