wm_sorg

I have an 88 Formula 350 with a factory GM alarm system. The battery will not hold a charge overnight. I need some ideas to help determine the source of the drain. I have not tested the alt for bleeding across the diodes yet.

My question would be what systems have access to battery power when the ignition is off? If possible I would like to disconnect systems and isolate the drain by trial and error.

Any suggestions would greatly appreciated.

RSpeed

The only systems I can think of off the top of my head is the alarm system and the memory/clock source for the radio. If you have any amplifiers added to your stereo, you may want to turn off your stereo and check to make sure that the remote turn on is off and not keeping your amps on. Check your alt to make sure it's fully charging.You can do this by checking the voltage at the battery with the car off, and checking voltage again with the car running. As you may already know, the voltage should be higher. But for now, that's all I can think of. If I think of anything else I'll let you know.

Tim Burgess

Try putting an amp meter in series with the battery & measure the current draw with the engine off & all the doors closed. It shouldn't be more than 0.05 amps, or so.

If it is, then (after removing the dome & courtesy lights & unplugging the rear view mirror light, if your car has one) remove one fuse at a time, until the current draw is gone. That will tell you which circuit the current is bleeding through.

Tim

Topgun

It might be a bad battery too. Some batteries won't hold a charge. Have you batteryu and charging system checked

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COUGAR

i would start this one by checking out the battery. i have had this problem with all of my f-bodies. battery gets older, power drains over night, tried all of the trial and error stuff, and it always came down to a bad battery, here is what you do. when you get home to park the car for the night, disconnect the battery from the cables and let it sit there, if you come out in the morning and it is low on power, buy a new battery and all of your problems are gone, if it is still carrying power, start in with the trial and error elimination rounds.\

hope this helps you

wm_sorg

Gentelmen:

The battery checks ok. Looks like I have to hook up an amp meter and pull some fuses. Are there any hidden ones not in the fuse box?

Tim Burgess

There is a 20 ampere fuse for the ECM, fuel pump, mass air flow relay, and burnoff relay near the battery, bolted to the frame near where the small ground wire from the "-" terminal from the battery attaches to the frame.

There may be a 4 amp in line fuse for the under hood light, near the hood hinge.

The alternator, coolant fan relays, blower high speed relay, light switch, fog light relay, and ignition switch are powered through "fusible links" down at the large terminal on the starter. They may be removed from the post on the starter, one at a time, if the fuse removals do not locate the source of the current drain.

Tim

wm_sorg

Tim are any relays supposed to be active then the car is off? When connecting and disconnecting the battery, I hear some relays activating on the relay block where the fuel pump relay is located.

Tim Burgess

There is a MAF power relay and a MAF burnoff relay - one is near the battery & the other near the fuel pump relay - I'm not sure which is which, though. The burnoff relay has battery power to its coil & pole contact. The ECM grounds its coil to turn it on. I know that the burnoff relay remains on for a short time period, after the ign is switched off, so maybe it is cycling after the power up. It should not be on permanently, though.

Tim