Just got a newer motor (used 05 sedan with 60k motor) swapped in my 03 6MT coupe due to bad piston rings. Now the battery drains overnight (less than 8 hrs)... I removed the bose amp and radio fuses to see if that would help, but I woke up today and the battery was dead again.... I'm pulling my hair out over here.

any ideas?

 

more info:

at first when i went to pick up the car it wouldnt start so we switched the ECM relay with a relay thats identical, just on the other end of the fusebox....

that didn't help so then we started taking the engine apart... took off the intake and plenum and checked spark plugs. everything was fine so we put everything back together and the car started up just fine..

since then, every night the battery has drained completely

 

get a regular teest light with a normal light bullb NOT an LED.
pull the negative battery cable off and clip the wire from the test light to the negative cable.
use vice grips or another kind of locking plyers to clamb the the other end to the negative post on your battery.
leave the ignition off and the key out of the vehicle, turn off the interior light and everything else that you can make sure it all is off
once you connect the test light the light on it will light up if there is a draw on the battery.
start pulling fuses one by one to see when the light goes dimmer or off, you may have a draw in more than one fuse, and the light may not go completely off because of the clock.
when you find what fuse or fuses it is that makes the light go off than look at what the fuse it labeled and that will tell you what system the draw is in and where you should start looking.

goodluck

 

yea, just did that..... RIDICULOUS draw...

5.15 A.... until I pulled the AC fuse behind the battery and the amps dropped to 1.6

then I pulled the ECM relay and it dropped to just about 0!

I think i found the culprit!

 

actually I just put the 2 relays i had originally switched.... then rechecked.... now im pulling 1A... which is significantly less, but still lookin for the source of drain...

 

ok update again...

continued testing and found the ign con ECCS was drawing .3 amps and the radio was drawing .5 amps...

tried starting the car, and it started right up, then died 20 seconds later.... check engine light and battery light popped up.... now the car wont start at all

 

i would maybe start checkin all your engine grounds and look for any of the plugs and wires that were unhooked during the motor swap. then maybe those relays if their making a draw then not a draw maybe grab replacements from autozone or somehting i think their only a couple bucks each

 

autozone doesnt carry the relays that go inside the ipdm box, or else i would have bought one today...

 

I had the same problem when my previous car was boosted. Turns out, the idiot who installed my DEFI gauges did it incorrectly. And the gauges were draining out the battery.

 

car starts right up with the 2 relays switched... but draws 4 A.....