Croc

After just over 2 years of ownership, I had my first major issue with the car yesterday.

I started the car in the morning, noticed the lights in the instrument cluster was dimmer than usual, without thinking too much, I put the car into reverse and the reverse camera did not engage. I then realised the whole Comand system was not ON and could not be turned ON manually. I drove for about 500 meters and hit the first set of traffic lights and got this wonderful idea of restarting the car in the hope that it would start the Comand system just like what you do when you have a computer problem and how wrong was I. The car would not start at all; the instrument cluster continue to light up, the climate control fan was functioning, and electrical windows were working too, but Comand was dead, engine would not start and even the bloody hazard lights wouldn't work! Great fun at a busy intersection during peak hour traffic!

I turned off everything completely and tried to start the car, multiple times, with zero luck, so I called roadside assistance and help arrived about 1 hour later. They also could not start the car, so they reconnected the battery, at which point, the car came back to life. They reckon it was an electrical failure and asked that I take the car to the dealer.

But after putting the car through the full health check at the dealership, every test passed and they also could not find any error code stored in the onboard computer.

Anyone else experienced this? or heard of similar stories?

Plutoe

I hear these stories all the time, typically on Friday and just after the pubs have closed, folks are pissed and their car wont start---most of the time the car does start when the owner realizes that he is trying to start his girlfriends car with his key or he is on a tractor and trying to start-----your issue is rare--broad daylight and no reported booz--that's a tough one--you may want to trade the car too many problems!!

Mike5215

Reconnected the battery? Is it possible one of the terminals were loose?

stockbmw

Door didn't close fully? Does our cars have auto interior light shutoff when on for more then 1hr?

DBOC205

^ Faulty door sensor is probably good line of thinking, but you should still be able to start the car or manually bring the COMAND system to life. Did you try using the key in the dash as well as the keyless go?

I reckon go see someone who has Xentry and get a print-out of the full diagnostic quick test report for reference. The modules report on exact odometer time/date for even minor hiccups. It would be really surprising to not see anything at all on that report.

Fingers crossed it won't return Croc. Doesn't sound like the sort of issue you want a repeat of in traffic.

Croc

Not possible as I said many of the electronics were still working.

Croc

Its not flat battery if thats what you are suggesting.

As I said, the car did start initially, but Comand didn't turn ON. Other electronics including climate control were still working.

Croc

Would an authorised MB dealer have Xentry? Thats where I had mine inspected. I am booked to go back in mid March and they would like to keep the car for a couple of days.

Mike5215

It's actually very possible. A loose terminal can draw enough voltage to run some of the accessories but not enough amps to start the car

DBOC205

Oh yea, of course they have Xentry. That's the software suite which interfaces with the car for all things software related to the car modules. They will use a multiplexer (which hooks to the OBD port) and then that talks (mostly wireless these days) to a computer running Xentry Diagnostics.

Most dealers just don't let you peer over their shoulder whilst they use it however because it's done inside the workshop where they don't like folks wandering about. You could ask for a printout of the "Quick Test Log" though (it should be about 8 pages in length, showing each module, software etc, plus not only faults but also 'event' conditions which fall outside of normal parameters and they're all logged in each of the modules). If you want a sample PM me. The problem is that you can clear the fault log to see if anything new comes up when running a new suite of tests. If they do that then you're back to square one and you'll have to wait until your problem occurs again.

Shadwell

also possible to have a battery showing 12.7v static but not be able to provide the CCA to start the car.


Recharge if possible, replace if not.


I have had new batteries under warranty on the last 2 mercs, despite recharging monthly on the wife's car and weekly on mine..


Dash cam's with parked recording timers and battery savers still pull the battery down... which combined with many short trips can bugger them up..


I have had no issues since and maintaining a recharge regime.. (peace of mind really)..

JBMCL

I had a similar situation happen but it wasn't as serious as yours. I started my car one night and the Command didn't turn on. I tried to turn it on manually via button and nada. The car ran fine but the backup camera obviously didn't engage cause the screen wasn't on. Audio and climate control worked fine.

I was in a rush, so I drove to my destination and parked. After an hour, I turned my car back on and everything worked fine. Weird..only happened once *knock on wood*.

Croc

Ok, but you would think if there is any voltage, the first thing that should work is the hazard light?

Croc

I did get a quick browser of the test report on Monday. It was quite a few pages, and every test had a passed mark.

Croc

Road assistance was able to get the car to start simply by reconnecting the battery. No recharge was done. The car was also driven the day before, and serviced only 1 week earlier. I highly doubt it was the battery.

Croc

Sounded like a lucky escape!

There is another difference - I couldn't get audio to work in mine, given its part of Comand. So not sure how your audio was working? maybe your Comand was ON, just not the screen.

JBMCL

Yeah. It seemed like most, if not all the functions was on/working but the screen wouldn't turn on.

kleinebin

Fire risk after the vehicle not starting has lead to a Worldwide recall :s

https://mbworld.org/forums/c-class-w...fire-risk.html

Mike5215

Who knows. You'd think so but Mercedes electronics are cluster f to troubleshoot. Their one saving grace is that they normally trigger a fault code, but yours didn't.