I've been having an intermittent problem with my '05 MC. I've search the forum, and have found people that reported similar issues but not quite the same. Here's my scenario:

1) Unlock doors using remote, window rolls down and back up upon entering, put key in ignition.

2) Turn key to on, and the typical chimes, dash lights, etc. all work as normal.

3) Turn key to start, all electrical devices turn off... lights, chimes, all the dash gauges, etc. The engine doesn't turn over, and I don't even hear a click.

4) At this point, I've only found one thing that will bring things back to life. That is removing fuse R1 (engine compartment, marked with what looks like an engine symbol), wiat a second, then re-insert. I'm guessing this "reboots" the computer?

5) Return to step 2. 90%+ it starts right up.

This happens periodically, sometimes multiple times in the same day, sometimes several days apart. It began randomly one morning with the car in the garage.

Now when this happens, I lose all of my clock and all the trip data, (trip odometer, average fuel economy, etc), which is probably stored in the computer. Radio presets stay, as power was never cut to the radio by removing the fuse in R1. I don't have to disconnect the battery. Occasionally, and this seems to be less common, I see this same data lost without having to pull the fuse. This happened last week a couple times.

I've checked the battery (whlie it's in the "i'm not going to start" mood), it has a strong 12.5-13 volt charge, and is less than a year old. I've double checked the connections, they're solid... and that doesn't make much sense that it would be a battery problem since simply pulling and replacing the fuse normally fixes things.

Typically, this isn't such a big deal and I've been living with it for a few weeks mostly because its a pain to take the car in, and its not under warranty (salvaged title). This morning however the car got stuck in the church parking lot and it simply wouldn't start, I tried my normal steps several times with no success. It was sitting outside in 110 degree Phoenix weather. Even thou I was pretty sure it wasn't a battery problem, I tried hooking up jumper cables anyway. With the cables hooked up, I could hear the solenoid clicking, and the interior lights/dash/chimes all stayed on, but the engine never turned over. Giving up on that, I went home to get some other tools. Upon returning, I decided I should move the car into the shade, so I put the keys in and turned them to On so I could steer, and lo and behold the chimes and dash came on (I hadn't played with the fuse at this point), so I gave it a try, and it fired right up.

I'm pretty much at a loss for what to do, other than taking it in to the dealership (a nice 35 mile drive), but, I don't really like taking my car in for service without having a clue what the problem is. I'm hoping someone on here might have some advice on things to try, or perhaps you know of a good place aside from the dealership near Tempe AZ where I could take it. (I've been to one BMW shop for some other minor things that I couldn't fix myself, but they didn't know much about MC's). Thanks in advance!

David

 

Best bet would be to take into the dealer. Definitely a warranty problem. You may end up getting a new ECU.

 

Did you read his post:

Good luck with solving your problem, David - with all of the electronics on today's cars an issue like this is tough for anyone but the dealer to solve.

 

Yes I did.......and I missed that !

 

A quick update... since the last ordeal Sunday morning, the car has started fine every time (12+ starts). I haven't done anything to it! Intermittent problems sure are evil!

 

Still driving the same car, and realized I never responded to this with the resolution: The problem turned out to be a battery that had almost worn out. After replacing the battery shortly after my last post here I haven't had this problem again, even with subsequent batteries in similar conditions. Hopefully this information will help out someone else in a similar situation.