Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
hi, i'll be happy to help you in anyway i can.
sorry to hear of your misfortune :(
does it still start ok?
Yes, it starts fine at the moment.
thats good news.
are you handy with tools and want to give this a go yourself, or do you just need advice?
I would say that I am quite handy with tools and mechanical aspects of cars. Electrical items are another matter.
do you have a voltmeter?
ok, lets start with the alternator.
start the car up and put your voltmeter across the battery.
anything less than 13 volts is a bad alternator.
after that turn the headlites on with the engine off for 1 minute.
OK. That will take a couple minutes, I need to clear a lot of crap out of my wife's trunk. Back in a few minutes after I do that start the car and check the voltage.
if the voltage is less than 11ish replace the main battery.
beyond thats its more likely the battery control module.
dont worry about the aux battery for now.
aint this remote diagnosis a hoot lol
OK. Good news. 12.2 volts with engine off, 14.0 volts with engine running. I assume this means the alternator isworking.
very good news. alternator ok, main battery probably ok.
probably a bad battery control module.
additional good news, believe it or not it may just be software.
will require a trip to the dealer, i'm afraid.
be prepared to pay 1 1/2 hours labor for diagnosis. if the repair seems reasonable, just do it.
if the come back and say you need an $1800 something or other, check w me before you buy.
I did not try the light test, as I left to check voltage before that came through. Should I still do it. Is the battery control module expensive, and does it need programming, or is it a DIY?
Also, I am new to this caht stuff, how do I get back to you after I see what the dealer says? Finally, given that the alternator seems to be generating power, is it OK to drive it to the dealer (about 5 miles)?
See last couple follow up questions.
I think that covers it. I am thnking that I buy the BCM and install it to see if that fixes the problem Cheaper than 1.5 hours of diagnosis.