Thinnman

2000 Monte Carlo SS 3.8 it has a new battery and new alternator. I started out with 1.87amp draw originally but I found that the radio was drawing .45 amps so I connected the radio to a Key on aux power. The alternator itself was pulling .96 amps until it was replaced. The wires on the small connector to the alternator all show the correct voltages with engine off, pin D orange wire 12v always on, pin L red wire is 0v. The Amp meter now shows a .46 amp draw until the 15amp PCM fuse is pulled and replaced, then the draw goes down to .001 amp and remains there until the car is started again. Once the car has been started and stopped and left sitting for 1/2 hour to go through a full shut down, it goes right back to the .46 amp draw. I found the 10 amp BCM/Cluster fuse is also showing the .46 amp draw. When fuse is removed, it also shows a .001 amp draw but only until you put it back in. I tried to connect it like I did the radio to a Key controlled power source like the power mirrors. Everything seemed to work with it powered that way when you turn on the key. But then the car acts like it has a dead battery when you try to start it. I've been working on this problem for a year now and I'm just about to given up. The wiring diagrams that I've found on line have been very little help to me. Any help is greatly appreciated. I can't determine if its the BCM or the PCM that's causing the problem. The 2 car repair shops that has looked at it have not been able to find what is causing the draw. I'm a electronics tech but this beyond me. Please help

kevinkpk

Well, the body control module is drawing almost 1/2 amp constant? Try isolating it from frame ground. There shouldn't be a total of 150 milli amp total parasitic drain on the total system, including the radio. Keeping in mind original factory.

tech2

your almost there...continue what your doing. if the draw is all on the bcm/ipc fuse print out a power distribution diagram of that circuit and see what components the fuse powers. start unplugging components one at a time until the draw is gone.

Thinnman

Thanks for the help so far. Sorry for the delay getting back, but I have only the weekends to work on a solution. I looked at the BCM but didn't have any luck on isolating the ground and pulling all fuses had already been done. But this past weekend I did happen by accident to get the draw to .001 amps. I had substituted a screw driver for the door striker in the door latch so that I could leave the door open to get to the BCM. This caused the draw to drop to .001 amps and it stayed there even after multiple attempts to get it return to the .46 amp draw, even after 3 engine restarts, removing the screw driver and opening and shutting the door several times. The draw remained at .001, but the big test would be to let the car sit for 72 hours to see if the battery was going to stay charged. But, after it had sat, the car had not even been touch not even the doors I rechecked it and the draw had returned to .046 . I tried using the screw driver in the latch as before but couldn't get it to drop again. I took the door panel off and started to remove the latch and saw the 3 electric connectors attach to it, but I ran out of time and daylight before I could disconnect any of them. I'll try to discount them one by one this weekend. I think one of them has to be for the power locks and the other is for the alarm, but I have no idea what the 3rd is for. Pulling the fuses for the locks and alarm had no effect on the draw. I guess I'll have to buy a repair manual in order to get a schematic. I can not find one on line that has the door, BCM or power distribution on line.