Battery and alternator ok, but jump starting car

[Seraffa]

Hi. Strauss Auto says the battery and alternator are ok on my 1991 toyota camry, but the battery gets slightly drained overnight and the car won't start without a jump. Once jumped, the engine idles high for a few minutes. The tech says it needs an electrical diagnostic ($85) but I don't have $85.

I've started unhooking the battery every night then reconnecting in the morning, and the same thing happens without the battery draining.

My boyfriend thinks the car needs a new coil. Any clues?

[Mike Gerber]

If the car starts up fine with a jump, then the coil has nothing to do with the problem. I would start by checking all electrical connections between the battery and the starter, looking for loose or corroded connections. All connections should be shiny clean and tight. I would pick up one of the terminal cleaning brushes available at any auto parts store for a few dollars and clean all conenctions. If the problem still exists after cleaning/checking all connections, I would then check for a dark current draw. That's the current that the car uses with the engine off for things like the computer memory and the radio presets. You will need a digital volt/ohmeter for this test. Do a search on this forum for the term "dark current" and read up on how to do this test. It has been covered several times before.

Mike

PS: If you have an aftermarket alarm system on the car I would remove the fuse from that as a test. See if the car starts normally the next day. I have seen poor wiring on aftermarket alarm systems cause an excessive dark current draw.

[Seraffa]

Thanks! That's very valuable help -----