RobbieLu

Hello!

I got really big problem with Red battery message ( Visit workshop)

I scan Battery Control Module with my diagnostic tool i get fault code "9055 - The terminal 61 signal on the CAN bus is missing or is faulty."
but that fault code say nothing for my problem.

Problem 1
I also check voltage output from my alternator to main battery guess what? i got 12.3v seems fault is here but its not i change alternator to the new one, and still get the same voltage output from alternator, but something interesting is that, when i accelerate output goes from 12.3 to 13,9v and 14v and doesn't goes down, seems okay? i think it should go to the 13.5v when i start engine without accelerate? then i check "Drive Belt Tensioner" i change it also because it was in bad condition, but still same problem with charging a battery from alternator, doesn't charge if i don't accelerate on high revs.

I also change both batteries "AUX battery and Main battery" still got the same problem Red Battery Message on my dash, then i change Aux Battery Relay and clear the codes with my diagnostic tool, start the engine and again same pop up with "Red Battery Message" i took my voltage meter and checked Aux battery with engine on, got 12.2v seems its not charging, i being to look all fuses, all fuses was in good condition expect one in "F32 fuse box" i change it and i got the same fault code on my dash.

Then i change Battery control Unit but problem was not gone.

I spend a lot money to trying fix that "Red battery Message" on my screen.

Maybe you guys will help me to find out my car's problem.

Sorry for bad English.

konigstiger

Assuming vehicle is MY03-06 could be the relay (current part # 0025424719), faulty relay will give you red warning. If f70 was bad (front prefuse, interior foot well) this is for battery relay http://workshop-manuals.com/mercedes...ion/page_4935/ to replace see here (wheelhouse) http://www.google.com/url?sa=t&rct=j...,d.eXY&cad=rja

RobbieLu

Hey! Thanks for your reply!

but i have tried 3 Aux battery relays, i bought one new aux battery relay from local car parts shop, the second one is old from my car the OEM part, third one i had try to put from my friends w211 also OEM part. Still same Red Battery Message

konigstiger

Have someone clear/pull codes with MB DAS. If alternator is rebuilt (usually a weak point in this scenario) revisit other than this not much more I can offer.

RobbieLu

Problem fixed, found broken wires from alternator.
also needed to change voltage regulator, because of short-circuit.

Scrandan

Hi there would you be able to tell me if the broken wires you found was the two skinny wires in the plug the go into the alternator please

boogsenior

check battery control module in trunk ( usually near trunk latch). Sometimes electrical connections are not plugged all the way in to the module. causes warning light to go on. Worth a try.

rapidoxidation

Responding to a 3 year old zombie post from a n00b...
Slow night at work?

cetialpha5

I think it's the mobile site. Tends to show old threads after a new one so if you keep scrolling and don't pay attention, all of a sudden you're replying to an old thread without realizing how old it is.