My '02 R50 is possessed! My first electrical problem started a few months ago. I ran through a deep puddle in heavy rain and immediately thereafter, got the dsc, abs, brake light trifecta. Reading the forums I assumed I had a bad wheel sensor. I bought a front and rear sensor and swapped them out one at a time and.....nothing, also no evidence of wire chafing or wet/corroded connectors. I took it to one of the only two garages in town that works on imports. They scanned it and told me that the sensors are working but the ABS module has a checksum error and needs replaced or rebuilt but despite the lights, the ABS appeared to still be functioning.

I let that slide until I had more time to deal with it, but last week it went nuts. It was parked outside in the heavy rain. When I went to leave for work, I turned on the headlights and got dash lights but no headlights. I turned the car off, did an ecu reset and then....I had headlights but no dash lights and the blower motor will run without the key in it. Other new issues also appeared, no turn signal indication in the tach and no chimes for turn signal, key in ignition or headlight on and no key.
I did more poking around on the forums and decided that I needed to check connectors. Grounds are tight and clean. I unseated and reseat all connectors to the fuse box and the the body control unit in the other kick panel, hook the battery back up and now the airbag light joined the party.

I am an experienced shade tree mechanic with good electrical troubleshooting skills but this can/bus stuff is baffling. I would have cried uncle and taken it to the dealer already if the closest one wasn't two hours away. Anyone else been down this road before?

 

Does this car have a sunroof?

If so check the drains by pulling the headliner down. If they've popped off refasten with zip ties.

I suggest starting with the BCM do a search and you'll find out more.

 

No sunroof. BCM, that is the unit by the hood release, correct?
I found that the foam padding under the drivers carpet was wet but no standing water and the passenger side was dry.

 

I would also check the two corner pieces of trim on the a-pillar. MINI really cheaped out and made a plastic clip where the foam gasket rots away. If they're loose buy new clips.

I would also make sure the cowl is draining properly.

I suggest finding out why water is getting in the car to before trying to fix anything. There's a lot of expensive stuff that is getting wet.

 

Are you referring to the black plastic outer trim that runs vertically or the thin black and chrome piece that goes under the windshield and wraps around the A pillars? I had a windshield replaced a couple years ago and the shop tore up one of the black plastic pillar covers and couldn't get it to stay on when they were done. Although they bought me a new one, I can't imagine they were any more careful with the other one.

I have removed the BCM to examine for water damage and see no signs of water. I will say this...BMW is a perfect example of penny wise and dollar foolish. The BCM is completely unsealed and the board isn't even coated so even if it doesn't get directly wet, very high humidity could do damage.

 

Bump......lots of reads not many suggestions.

I was out of town for a bit and had little time to investigate.

I have since tried several things.
All connectors in and around the fuse box speedo and BCM- clean, dry, and intact.
All solder joints on BCM touched up to make sure that there were no cold solder joints.
Ground to motor, body, ECU, BCM, fuse box, and every metal spot I could find are good.

Found that F5 while not blown, only has 2v on it.

It's not that I am trying to be a cheapskate, I have no dealer

 

I would drive the two hours, the dealer will sort it out, just bring a wad of cash. Two hours isn't that bad some people don't even have the privilege of a dealership.

 

What is the age and condition of the battery?

 

Battery is three years old and checks fine according to the local parts store.
As for a trip to the dealer....I don't get a warm fuzzy feeling driving a car with ongoing electronic issues two hours away but it may yet come to that.

 

I spent a good portion of the day pouring over the wiring diagrams, checking fuses, and connectors. I was trying to see what the common thread was on the diagrams and it clicked about something I read in another thread.

Since this weird dash light problem started, the radio fuse (F27) has blown a few times but each time I replaced it, the radio (aftermarket Sony) worked for a few days, maybe a week or so before blowing again. The thread I had read before was about some weird electrical problems caused by the CD changer connector in the boot. When I lifted the rear carpet, it was pretty obvious, at least the radio issue. There were the two connectors burnt and badly corroded with evidence of water having been the original and ongoing cause.

I disconnected the battery, cut the connectors off and put shrink tubing on all the severed ends then pulled the harness up into the side cover behind the tail light. I reconnected the battery and to my amazement the dash lights, instrument indicators, all working again!

 

Yikes !

Glad you found it.

Looks like something chewed up the wires, if you need new ones let me know.

 

Good to hear and thank you for updating thread for future reference.

 

This is the exact same problem I had, carpet was soaked and the connectors Tucked under the carpet. Pretty sure I fixed my leak back there, although I am still dealing with a big leak in the front rain gutters, maybe you should check that spot too before it causes you the hell it is causing me.