Quote:
Originally Posted by spark3542
Here’s the current update (no pun intended)…
Cant find a fused circuit that is drawing…pulled all fuses one at a time
Installed new regulator (took 2 tries to get the right regulator…the most common one has a connector that comes straight off the back, but that interferes with charge air pipe, so special regulator with connector off to the side is required for the diesels).
Now immediately after start I get red battery screen of death and all “convenience” functions are disabled. I confirmed both from obd2 and voltmeter that alternator is charging. I even swapped batteries
Anyone have any insight as to why regulator change would give this screen? Again alternator IS charging, and battery IS good, but all convenience function remain disabled as long as the engine is running
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Firstly - you cannot remove fuses to find a battery draw on these cars as removal and install of a fuse can wake up a module and that module wont go to sleep/dark mode until its cyclic sequence - e.g. car locked etc.
Secondly - you have the wrong regulator on the alternator, the linbus is not able to communicate with and hence is showing that error, the good thing is that mercedes have designed it such that it will bootstrap itself and start charging the battery to full juice after a period of 10 seconds of no communication from the alternator regulator.
to find the draw, open the doors, trunk, hood etc and then lock all the latches with a screwdriver along with taping all the push buttons shut to fool the car that all doors are closed - then lock the car and leave it alone for about 10 minutes.
now one by one use your multimeter on 20DCV and check the voltage drop across all fuses and write them down.
find the bad circuit with this
https://www.underhoodservice.com/tech-tip-volkswagen-diagnosis-for-excessive-static-current-draw/