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blaisetd
July 17th, 2010, 10:45
So i took my 2001 xj (4.0 auto) out of storage and cleaned it up. Istalled a fresh battery and it started and drove fine. I let it sit overnight and the battery was deader than a bag of hammers. I charged the battery and used a test light between the neg terminal and ground to find the drain. I found the IOD fuse the power distribution block was the culprit.
IOD fuse description:
"The IOD fuse feeds the memory and sleep mode functions for
many of the electronic modules in the vehicle as well
as various other accessories that require battery current
when the ignition switch is in the Off position,
including the clock. The only reason the IOD fuse is
removed is to reduce the normal IOD of the vehicle
electrical system during new vehicle transportation
and pre-delivery storage to reduce battery depletion,
while still allowing vehicle operation so that the
vehicle can be loaded, unloaded and moved as needed
by both vehicle transportation company and dealer
personnel."
Pretty sure the IOD shouldn't kill the battery in 10 hours. Anyone have any ideas?? TIA blaise

joe_peters
July 17th, 2010, 15:07
Ok, the IOD circuit should NOT have enough of a draw to drain the battery, even after some weeks of sitting.

Did the test light come on BRIGHT or DIM? If it comes on BRIGHT you have enough of a parasitic draw to be a problem. If it comes on DIM, then the circuit is normal and low enough that the battery should maintain its charge.

Did you fully charge the "fresh" battery before installation?

blaisetd
July 17th, 2010, 18:59
Ok, the IOD circuit should NOT have enough of a draw to drain the battery, even after some weeks of sitting.

Did the test light come on BRIGHT or DIM? If it comes on BRIGHT you have enough of a parasitic draw to be a problem. If it comes on DIM, then the circuit is normal and low enough that the battery should maintain its charge.

Did you fully charge the "fresh" battery before installation?

Yeah, the battery was fully charged both times i put it in. The test light is very bright with the IOD fuse intalled and actually dim but still lit after i pull the fuse. Weird huh? blaise

Shorty
July 17th, 2010, 19:05
have you load tested the battery? A marginal battery can function after a charge, but not be able to store enough power to crank the engine if left alone over night.

joe_peters
July 17th, 2010, 19:15
As Shorty suggested.

Also, leave the fuse in and start unplugging items on that circuit--PCM, radio, clock. You can probably isolate the accessory/section of harness that is bad.

blaisetd
July 19th, 2010, 11:05
Checked it again Sunday and no drain at all. Weird.

joe_peters
July 19th, 2010, 16:54
Maybe a sticking relay in a circuit, just monitor things to see if it occurs again.