Wednesday, January 4, 2017

W211: The Most Ridiculous Battery Drain Problem Ever, 2003 E320, P.4

An update...car's still draining lol

Now that I've got an occasional break to check out the car, I believe I've got it fairly well isolated.

Car got a new rear SAM, as through some testing, I've found a few options on the car non-OP. With a new SAM in the rear, everything on the car is A-OK and isn't showing any coding problems which it seemed to be doing before. I've also got a MOST bypass where the teleaid module was and coded the teleaid out of the system. If you simply remove the teleaid you'll get an SRS warning light on the dash, because the teleaid runs through the instrument cluster and airbag modules on the car. Code everything to "Not Present", reset the optical loop and you'll have a perfect functioning MOST system without the teleaid being on the consumer circuit.

After running through the Mercedes canbus isolation tests (completely disconnect x30/4,7 etc) from the system - everything is in working order! Go figure - BUT, through some nonsense testing, I've completely isolated the battery drain to the interior fuse box (F34). How? Keeping the multimeter set up for parasitic draw, I've disconnected the rear pre-fuse box (F33) power wires one by one to see if any major systems were draining. F81 red cable apparently feeds the entire F34 fuse box.. when disconnected, there is no battery drain present - connected, drains like an open artery at a steady 1.5amps. Mind you, removing individual fuses would NOT give me a result! Car is apparently going to sleep as well, as when immediately shut off, it sits at around 3.8 amps and will steadily drop down to the 1.5amp draw. No more fluctuation with the new rear SAM, so progress is being made it seems.

Now, when I get some more time, I'll figure out exactly which circuits the F34 fuse box powers and run through unplugging the modules themselves and see where we go. I noticed the central gateway is part of the F34 circuit, so it's a possibility that it's keeping some consumers awake. We'll see with time I suppose!

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