Quadcammer

First off, sorry for the cross post, but I wasn't sure which section would be best:

Vehicle is a 2000 E430 4matic, totally stock with 64k miles.

Battery will die after about 3 days of non use. This is partly due to a weak battery (from all the drain/recharge cycles) and partly due to a viscious drain.

With a fresh battery, it will last a week or so, and thats it.

Heres the situation.

With all fuses in, draw reads at 140 ma.
Pull every fuse but #16, and there is no change in that figure.

Pull fuse #16, and the draw comes down to 10ma, which is all good.

Fuse 16 is for the heated/adj mirror, the memory seats, the ds window, courtesy lights, and central/convenience locking.

This screams door control module...which the dealer agrees with.

So I order a new door control module, pop it in there, same problem.

When you remove the door control module entirely from the system, the draw is 330ma, which to me indicates that the can-bus is not going to sleep cause the module doesn't respond.

So now I've reached the limits of my electronics diagnosing ability and need your guy's help.

If anybody has any ideas/suggestions, I'd really love to hear them.

Wiring looks ok on the door with no apparent fraying, and all apparati work fine (memory seats, mirrors, etc).

Any advice would be very useful.

Thank you.

Quadcammer

scratch that, after about 20 minutes, with the dcm off the door and not at all hooked up, draw is down to 10ma.

Quadcammer

ok, further elimination.

The plug featured in the following pictures is what is causing the draw. Something connected to this is the issue.

Skylaw

Wish I had the wiring diagrams to assist with your very nicely documented statement of the problem. I came to the same conclusion you did while reading your first post - the DCM. Without it being that, (stating the obvious) one would have to see what else is connected to that plug. Time to sign up for a 1-day subscription to http://www.startekinfo.com/StarTek/

Quadcammer

Thanks for the tip skylaw. Hopefully the wiring diagram will clarify.

Quadcammer

Problem solved.

The Infared sensor in the exterior door handle was bad somehow, causing the 140ma draw.

Once those wires were disconnected, draw dropped to 10ma.

Its my mother's car, and she didn't even know she had the summer convenience feature, so I just left the wires disconnected.

Tracing this was a massive pain in the ***, but in the end, it was worth it. $115 an hour for diagnosis would have been painful.

Anyway, cost $18 for the WIS subscription, but thats it.

Diesel Benz

Thanks for reporting the solution for the problem. The IR sensor failures have been reported at the forum before but nothing has been mentioned about the related quiescent current issue. It would have been interesting to know from the other cars if they too suffered from the additional current draw. If the car is driven daily, the owner may not even notice a 140 mA quiescent current.

Quadcammer

Yup, on a fresh battery the car would last about a week before it was toast.

After a few drain/recharge cycles, 3 days were the best it would do.

She doesn't drive the car much, so hopefully this will solve all the dead battery annoyances.

Skylaw

Thank you for that feedback. This one is going into my bookmarks for sure.

UK-C200

Excellent diagnostic work, and thanks for posting up the resolution. I've had a bad IR sensor in the R171, but no current draw - it must have just died "open".