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harleys
03-09-2008, 02:57 PM
First i'll start with some info on the car:
89 Nissan 240sx Coupe
Sr20det swap
and other goodies that don't really relate to this problem.

Problem:
For a while now, the battery is dead if the car sits for more than a couple of hours. So today I finally broke out the multimeter to see what was drawing all the power. I figure out that it is the FL25A Eng Cont fuse under the hood. It's drawing about 10a with nothing at all on inside the car. I believe this fuse is for the ecu, so i tried disconnecting the ecu and it still has a draw.

Can anyone tell me what else this fuse powers? What could be drawing the power? I'm so tired of having to keep a jump box with me to start my stupid car. I tried giving all info that is related to the problem, if you need to know something else, just tell me.

Thanks in advance for the help.
slider2828
03-09-2008, 07:48 PM
I think pretty much the ecu.... check your grounds on the ecu... Pull it and see if it is still drawing.
harleys
03-09-2008, 09:35 PM
i did pull the ecu. even unplugged it still has the draw.
slider2828
03-09-2008, 11:31 PM
Check the wiring diagram.... sorry, try also the mafs.... which is connected o the Ecu as well.
harleys
03-11-2008, 11:38 PM
update: ok. figured out that it is the 02 sensor drawing power. if i unplug it, i have no draw at all. the red wire and white wire in the plug going to the sensor have continuity. not sure if it is supposed to, but doesn't sound right.
DataXUnknown
03-11-2008, 11:48 PM
I have the same problem! I'm gunna check my fuse tommorow, also the O2 sensor. Thanks! (My car is an '89 S13 with a blacktop SR)
PIwakawa
03-12-2008, 02:46 AM
my car had the same problem, just ran w/o O2, since there is no emission in florida.
Mangudai
03-12-2008, 07:44 AM
^ Doesn't thats affect gas mileage? Im assuming you mean the front o2 sensor..
harleys
03-12-2008, 11:59 AM
I have the same problem! I'm gunna check my fuse tommorow, also the O2 sensor. Thanks! (My car is an '89 S13 with a blacktop SR)

There are hundreds of things that could be draining your battery. It took me couple hours to narrow it down to this.
Drift_86
05-02-2016, 07:08 PM
I'm having same exact problem could some one pitch in and help me out?