Autotechnica

I'm having this battery drain problem and I can't figure out what it is. I've pulled out 3 plugs from the front portion under the seat. Here's a pic of the plugs.



Will doing this isolate the problem? The seat module is built into the seat correct? I've also noticed that all my dome lights are blown. I've pulled all the bulbs and unplugged the rear dome light as well. It doesn't seem to be working, the battery is still going dead. The car will run for hours on end once the battery is boosted. The battery is also 2 months old, so it's not that. Any other ideas for battery drain? I don't have the time to fix this problem right now, if I want to unplug the power to the seat, which plug is it?

BTW, I also have a DashDAQ logging device which is swithced off manually when the car isn't running. When the car is off, is there current going through the OBD2 port? It's so difficult to isolate the problem as I have to try things one at a time over a long period of time. It's getting annoying.

thanks,

Bryan

Glyn M Ruck

If you isolate the front seat modules & the overhead console A/C temp monitoring fan module you should no longer drain your battery.

Autotechnica

Can you explain which plug contains the wires that will drain the battery for the seat module, and can you explain how to disconnect the overhead console? I'm not too concerned about the seat motors, but how will disconnecting the overhead console affect the car? What's the fix?

thanks,

Bry

samaritrey

You did unplug both set modules right there is one under each seat.
And the black box under the seat is the module that causes the issue the other wires go to the motors and then to the car for power so by unplugging them they are cut off 100% from draining battery. so if both seats are unplugged then the only thing that usually causes issues as glyn said is the overhead console.

Autotechnica

I unplugged both seat modules. It didn't work, my battery is still going dead. I'm currently slow charging the battery 14V @ 2-3Amps. I've removed and completely unplugged the upper console/dome light. Hopefully that solves the problem, otherwise I'll be spending my weekend pulling fuses/relays till I find the problem.

Glyn M Ruck

The cause of flat batteries are modules or the whole CANBUS not going to sleep as they should. This thread covers the seat modules. You will find others covering the A/C air sampling fan in the overhead console. These are the common culprits. Comand can also do this if fitted.

If no luck. Pull the earth off of the battery & insert an amp meter or use a cable clamp shunt unit. Then steadily pull fuses from SAM's & cabin fuse block one by one until you find the circuit that is drawing the current.

Autotechnica

So i think it's the overhead console that's causing the problem. I had the overhead console unplugged and tested the battery this afternoon and it's still at 12.6V. However, does the entire overhead console have to be unplugged or only certain ones? is it the sunroof, dome lights, etc?

I have searched the other threads, and nothing mentions wiring or specific plugs.

thanks,

Bryan

csaunder

I'm going to work on my seat modules this weekend. Between TemjinX2's fix or SGTzAMG's on mymbonline which does everyone prefer? At the end of SGTzAMG thread someone said their SRS light came on, anyone else have this issue?

csaunder

Well, I did SGTzAMG's fix and so far so good. Everything works and no SRS light. I'll see on Monday if my battery is dead.

ENGc32

Hi Glyn,

I'm a new c32 owner and you obviously have a wealth of knowledge. A fan behind my COMMAND currently runs nonstop and I've tried searching diligently for a solution to stopping the fan. I still have a battery drain with my seats disconnected. Other than pulling a fuse I cannot get the fan to stop running. Is there a specific update disk to use for the system which will stop the fan? There has not been a surefire solution to this issue posted anywhere on the forum. (Other than just disconnecting the COMMAND fuse)
I would LOVE your or anyone else's advice. I hope you don't mind me sending you a PM as well.

Thanks in advanced.

Cale