Oka so my buddies 96 LHS has been draining his battery (new battery.) and while we were sitting around after replacing his radiator we swapped his interior lights with LEDs. Got the radiator/burping finished so we decided to tackle this draw. We found the draw was coming from fuse #23 (off the top of my head IIRC). Which is a 10 amp.

Background info: they replaced this fuse with a 20 amp because it would blow every time you pressed the trunk switch (only that switch blew it). Tested switch, all good. Replaced with led lights and nothing blew. Dropped to the stock 10 amp. Still nothing blowing.

So we sit there trying to figure WHAT on this fuse is drawing, and it's not a bad draw, 14 mA. Which is just even more confusing. Then he noticed the interior lights are on, dimly, but all 8 are on. We couldn't see this with the factory lights but the brighter LEDs exposes this. Let it sit doors shut for 3 hrs. Come back and still dimly lit. Draining the battery a whole volt. This leads me to think it's the BCM?

Am I correct in my assumption? This is the only issue we've found but obviously a dead battery is annoying.

The alternator has been replaced and I want to test the diodes in it also but it was doing this before the new alt anyway.

Thoughts?

 

how are you testing for the draw?

 

Remove negative cable, set multimeter to milliamps (plugging cable into amp slot), connect positive to cable and negative to post, gives draw on battery.

 

Then pull fuses to find what's drawing how much. In this case this one fuse is 99% of the draw

 

must wait about 10 min to have the computers time out then see what the draw is.

 

I did. With fuse out, basically 0 draw, with fuse in, draw doesn't change after waiting. Which means something isn't going to sleep, which is also indicated by the lights staying dim (unless that's normal but I've never seen that) which leads me to think it's the bcm. Windows work, trunk works, underhood and trunk lights stay off, radio acts normal, trunk switch is fine. I forget what all is on that fuse off my head at the moment. But we went through each part.

 

what fuse is it?

 

I believe 23. I'm away from the vehicle and can't find a chart on google. It's the fuses in cab. The one that has the windows/interior lights/bcm/ and a few other things on it. 10 amp mini, raised above all the others in the panel

 

IOD fuse there are alot of items on this fuse

 

Yes... I realized that when I opened the manual while pulling fuses...
We went through all we could test right then, but what gets me is: why are all my interior lights still dim even after the car sits for hours??
We closed the doors, lights dimmed away and appeared to be off but if you looked right at them you could see they weren't completely off.
Windows are fine
Radio is fine
Trunk light turns off when closed
Underhood does the same as trunk
I can't think of the other circuits on that fuse at the moment. It'd be really helpful if you could list them since I'm 10 hrs away from the car, I understand there's more or less a dozen. Then I can answer which circuits are fine.

But my question is why would the lights stay somewhat on??????

Would that be BCM?????

Some help would be appreciated, I know there is a lot on that fuse. Believe me if he hadn't seen the lights still on idk where we'd be on it.

Everything works as it should minus the drained battery (new), lights staying dimly on, and the trunk switch would pop the 20A fuse put in for replacement, but after replacing the lights with LEDs and checking the switch it no longer does, even with the oem size 10A.


So back to THE ONLY ISSUES being a drain on the battery (even tested mine out of my truck and the same drain happened) and the lights staying on dimly.