pa28pilot

one of the subsystems may have failed.

So my COMAND in the CDI would only power up to the three -pointed star screen and then would shut right off. This began after I had left my lights on while I ran into a computer store. I drove the car for a while to charge it back up, and only when I had driven for more than an hour in various trips, did I ever get a "some convenience functions may be temporarily unavailable" message, as I was driving to the dealer's shop.

My service advisor took the car away and brought it back, telling me that my NAV system had failed, that they had disabled it, and that I'd need to schedule an appointment. Everything other than navigation works again, as before.

The interesting thing is this - one failing subsystem appears to take out all of the others. If the dealer's diagnosis is correct, then a bad nav unit means that NONE of the Phone, the Radio, the CD drive, the CD changer,and the Sirius radio is usable.

Shouldn't the power-on diagnostics simply identify the bad unit and lock it out? I suppose that if the problem caused a break in the fiber ring that it might be problematic, but I was under the impression that MOST units failed safe, at least as far as the ring went.

Oh, and this was within 3 days of my U.S. delivery date. I'm still not clear on the effect European Delivery has on the start of the warranty period. It won't matter to me for a while, but does anyone know the deal there?

MBenzNL

that is what a ringsystem does - it completely dies as soon as there is one malfunctioning component in that ring...

Fiber goes IN the nav drive and fiber goed OUT the nav drive...if the nav drive is malfucntioning and no longer passes data, it all ends in the nav drive and there is no audio system anymore.

greetingz,

jimbo1mcm

On some 05 CDI's they had a mod to update the software in the Battery module because it wasn't providing enough charge to the battery. I hope they looked at that before yanking the Command.

pa28pilot

I had the [August? September?] BCM update. They haven't yanked the COMAND yet, it sounds like they'll just be replacing the NAV module.

You're right to ask about s/w updates though. I'm not certain how well service people actually read the service bulletins/campaign documents.

<RANT>They always say "the computer will tell us if there's one that applies to you." Is it too much to ask that a human being actually look at the serial number and check? Right now they're claiming that the latest SBC campaign doesn't apply to me. I'm not sure I believe them.

Anyone who knows airplanes knows that it's worthwhile to sit down and compare the actual serial number to an actual list of open issues. In fact, we collectively pay a fair amount every year to have mechanics do exactly that with every aircraft registered in the U.S.</RANT>

pa28pilot

Agreed, but the computer industry has found ways to prevent that sort of failure. There are fiber ring interfaces that will revert to a dumb "repeater" mode when the unit in question fails, as long as power is applied and the interface itself isn't damaged.

konigstiger

Can’t imagine that they didn’t check nevertheless…

Campaign 2005070017 – Inspect Alternator, Replace Regulator AUG05. The alternator regulator may fail to prevent voltage values ranging beyond the specified tolerance limits. As a result, the battery may be insufficiently recharged and the convenience systems may be shut off due to a resulting under voltage condition.

pa28pilot

Interestingly enough, they did replace the entire NAV unit/DVD drive. The comments are often somewhat arbitrary, but they wrote "DVD stuck", which seemed funny to me.

I know I left my lights on, but I can't imagine that causing a drive failure in the NAV unit. Go figure...

Silmeron

Ahhh crap... Same thing just happened to me today.

I left my lights on for about an hour/hour and a half, came back to my car, and now my NAV system won't power up. It sits on the MB logo for about 2-3 minutes and then dies.

...off to the dealer I have to go, eh?

Dvinn

I had that service recall done, plus another one called a battery regulator which was replaced as well.

TPAbnz

Does your car start?

Call Roadside Assistance. They came to my house on a Saturday for this.

bsmoove

If it's the same thing I had, this happened to me 2 before 2 and the only temp fix was to pull out and put back the fuse for the NAV thats located in the trunk by the NAV Disc drive unit.

The perm fix was a software upgrade at the MB dealer.

Good luck!