Eddy_Malese

I have a battery Visit Work Shop sign, the car drives well but interio lights aren't working. I bought a main battery, auxiliary battery and used alternator.

But still gives me the same message when I drive. I checked both voltage its 13.4v on both batteries, surprisingly when car is off for a while the convience function are available but immediatly i start it shows me the message.

Is there anything I could be missing or anyone who can help?

harjothundal

If both of your batteries are holding the correct charge at the time of startup, and your alternator IS outputting enough voltage to charge when running, then I would point all fingers at the BCM, aka Battery Control Module.

Eddy_Malese

Where could that be located

bbirdwell

In the trunk connected to the battery.

Eddy_Malese

Thanks I will check and get the part number and order one.

harjothundal

Here's the BCM. It's mounted on the rear of the trunk, at the bottom, next to the battery.

Eddy_Malese

Thanks once more!!

DocWilly

check bcm and x4/10 box under right front footwear because they are the easiest to check. if still not ok check central gateway module n93 using das

Eddy_Malese

Thank you I will check now.
Are these the bcm x4/10 fuse box?

DocWilly

x4/10 black box there are 4 clips to open the upper half and check the 150 amps fuse

DocWilly

bcm battery control module is at the back connected to the negative wire of the main battery which need to reset so it could communicate to with the instrument cluster
if still not ok then check cgm n93

DocWilly

mechanic just called me yesterday and the new cgm has been reinstalled and reprogrammed. initial drive test showed no recurrence of electrical gremlins. a friend told me that the weakness of benz is when the battery or alternator is dying it takes time before it will show as faults and will initially present with several errors rough idle high radiator fan convenience accessories shutting off and limp mode which disappears with restart. such that don't ignore red battery warning and if it appears replace all batteries especially if it's has passed 5 tears of service and change alternator if your car is old enough because if you just change the v regulator your not really sure when your alternator will conk out affecting your cars reliability.

DocWilly

last year my car when into convenience feature shutting off and high radiator fan with abs esp battery faults on instr cluster when by battery starts to die. then would not start when I shut it off. I tried unlocking the transmission lock and my car started but went home on limp mode with all faults on cluster and actually shutting off. when I check voltage on dyno the ffwing day .it seems normal and drove normal. but since the battery is about 8yrs I changed it. then 2 weeks ago alternator is dying but the errors did not initially confirmed it leading my mechanic to suggest changing the ecu because of multiple errors which I disagreed only few days later did it confirm alternator problem. but gremlins persisted after replacing alternator. bcm and x4/10 seems okay. when check using das the most common fault noted us the ecu communication with cgm n93 with can bus b and c. changing cgm corrected all errors

Eddy_Malese

Thanks Doc,

I have opened the x4/10 on the passenger but did not know how check.what I will do is open the four clips as you indicated.

I will updated you if there is any difference. Bare in mind I changed both main battery, aux battery and the alternator but still gives me the sign.

I think I have now other problems, yesterday drove around and the cars tarted to overheat, no pipe was leaking...the water cooler was steaming and temperature was almost 100deg. What could cause this?

DocWilly

check continuity of fuse with 150 amps mark if it's OK then it's not the problem. the fan is controlled by the engine module n3/10 which is the ecu. but the ecu is usually very durable so I drill look for other causes first I'll upload a pic and analyze from there about w211 networking.

DocWilly

rad fan is controlled by engine control unit and is under canbus c. while interior lights are under canbus b. b an c communicates via central gateway module n93. this needs das system for diagnosis. check integrity of n93 module.

DocWilly

Eddy_Malese

I have opened the bcm and I did not find fuses inside. It's a diagram.

DocWilly

x4/10 is not the bcm.

DocWilly

Eddy_Malese

That's located on the passenger site underneath the carpet? Which of the units I should open?

Eddy_Malese

Okay thanks, uhm... How do I know if the fuse is still okay?

DocWilly

use a tester to check for continuity of 150 amps fuse. use a digital multimeter to test continuity

justinp95

I need to check this. This is the first mention that this fuse even exists of a W211. I read a thread about a CL55 (or something like that) where the alternator wasn't charging and it turned out to be this fuse.

Also, how to you get that front carpet down?

Eddy_Malese

Thanks once more will certainly do so. Do you have a telephone number where I can contact you from. Otherwise mine is +27738028724