My 1998 Z34 has just over 140k miles and I've really not had any problem until now. Something is drawing power from the battery even when the car is off and it drains the battery in 2 days. At first I thought my problem was the actual battery because it's a 3 yr battery and this is year 4 for it. So I installed a new battery 3 days ago. That day and the next it was fine. Now, after sitting for 2 days it's so dead the car won't even turn over.

I jumped it and all was fine. The battery and alternator were tested and both are fine. Though I thought it was a long shot to have gotten a bad battery I had it tested anyway.

THIS IS IMPORTANT: Now, I can say, the DAY I put the new battery in, my wife played Mrs. Nice Guy and jump started a car in the local supermarket parking lot whose car was dead. My wife says that while she connected the cables correctly, the fellow whose car was dead connected the red to his negative battery terminal and black to his positive. She said she saw smoke under his hood and the cables melted about 10 inches from his battery.

Our Monte was fine and ran fine and started fine the rest of the day and the next day. The Monte then sat for 2 days. The battery was dead. that's when I installed the new one. It started fine after installation. I let it sit for 2 days. The battery was dead.

Here is what I did to try to figure out the problem: I disconnected the negative battery cable from the battery and connected my 12 volt test light to the cable and then to the battery's negative post. It lit up showing something was drawing power. I would expect that due to the stereo and clock. I pulled the fuse for the stereo and interior courtesy lights tripped by the door (I was keeping it open). I the pulled EVERY fuse and relay in the car and under the hood one by one, checking the test light and then replacing the fuse or relay. I was surprised. So, then I took every fuse and relay out in the car and under the hood and KEPT them ALL out. The darned test light never went out.

So something is drawing power from the battery that si not controlled by a fuse or relay! What could that be that is wired right to the battery? There's no aftermarket anything on the car except the stereo and that went out when I pulled the fuse. There is no alarm system.

Any suggestions? I don't know what could have been damaged when the fellow crossed the jumper cable lines. It still ran fine that day and the next so I don't know if that's what triggered the problem but I suspect my wife being nice has now created a problem. Like I said, the battery and alternator are fine.

Thank in advance for any suggestions.

Ron B.

 

After more research it seems I may have a bad Body Control Module (BCM). My symptoms match those frequently reported. Interior lights won't turn off. Elec door locks seem to work on their own. Parasitic battery loss. But how do you test the BCM to know if it's bad? I just replaced the starter for $128 for nothing.