If you unplug your battery when working on your car, you need to read this thread.

[timmay77]

This is probably the most embarrassing post I have ever made.

For those who do not want to read the whole post, scroll to the end of and read the last few sentences.

So a few of us gathered yesterday to put a new clutch/flywheel/RMS in DaytonDomer99's (Phil) 2002 M5. For those who don't know me, I am a machinery mechanic by trade, and I take GREAT pride in my work. The install couldn't have gone better. We had the transmission out in under 3 hours and the car completely back together and ready to go after 7 hours total work time. Problem was, it wouldn't start once we turned the key. It acted as if it wasn't getting gas. We checked EVERYTHING again and again. Checked for loos connections, pinched wires, among other things. We also swapped crank position sensors thinking it was bad. We even unplugged the CPS in my car to see if it sounded the same trying to start. It didn't. My car just cranked, never sent fuel, never even truly tried to start, just cranked. Phil's car was sending gas, trying to start, just wasn't getting spark. COMPLETELY different sounds when they each tried to start. The ONLY thing that happened, that was BAD, was when it came time to hook the battery back up, the ignition was left in the "on" or "2" position. I remember having to turn the wheel so I could install the support for the engine when pulling the transmission off. That required having the key turned on to unlock the steering wheel to do so. It must not have been put back to "off" and the key removed. We checked all of the fuses, relays, and any other electrical devices we could find. We unplugged the battery for 30 minutes and touched the positive and negative leads from the car together to totally discharge the capacitors in the ECU to do a full reset. Nothing worked. What we think (thanks Brian, aka WingsAA for researching this) that when the battery was hooked up with the key on, it went into a "safe" mode thinking it was being hot wired.

We exhausted all of our resources, calling all of the M5 gurus we had phone numbers for, and a few of their contacts as well. Thank you again, Peter, Steve, and Matt for your help. Even you Ray, without you knowing it, helped by being my friend. Mike at NE Motorsports is a true gentleman and was willing to help a complete stranger with just knowing I was friends with Ray and Peter. Mike, off the top of his head, had some GREAT suggestions and amazing knowledge of these cars. What a class act. Anyway, I ended up having to have the car towed to the local stealership where it now waits to be looked at. Tears filled my eyes, literally, as they pulled away with my friend's M5 on the back of a flatbed that I couldn't get running. Luckily Brian (WingsAA from Ohiobimmers.com) knows almost everyone at the dealership, and is going to work closely with them to diagnose the problem. Thank you again Brian.

Phil, again, I am SO SORRY. I will have your Beast repaired and back to you as soon as I can. I feel just as bad about having to put you in my Accord to drive until I do. It makes a great winter car, if you're me. LOL.


As of right now, we still don't know what it will take to get the car running, but I will update this thread once we do.

Cliff notes: When hooking your battery back up after finishing your work, make sure the key is NOT in the "on" or "2" position. BAD things happen. Make sure your key is off, or out of the ignition completely.

[mister2d]

What a nightmare! How can you guys sleep now.

Tell ya what, I'll stay up the rest of the night in hopes of sending some good vibes.

[M55555]

Thanks for sharing, and sorry to hear Tim. Hope it gets resolved ASAP.

+1 All nighter...

[timmay77]

Originally Posted by mister2d

What a nightmare! How can you guys sleep now.

Tell ya what, I'll stay up the rest of the night in hopes of sending some good vibes.

I haven't hardly slept at all, I am literally sick over this whole mess. I will gladly except the good vibes my friend......

[M5 London]

Tim,

Sorry to hear this.

These things happen, and perhaps even for good reason (someone up there made sure this car was not being driven (exposed to danger perhaps) on the road that day)

Did you check any of the fuses/relays in the E BOX ?

Good Luck and I am sure its going to be something minor !

Cheers

Kumaran

[timmay77]

Originally Posted by M5 London

Did you check any of the fuses/relays in the E BOX ?

Thank you Sir.

We did check the (5) 30amp fuses in the E box thanks to the knowledge of Mike at NE Motorsports. I had NO CLUE they were there until he pointed it out.

[djazz]

Best vibes possible from here too.

Sounds like an honorable response to an honest mistake.

dj

[TurboCarrera]

Before disconnecting a battery from a modern vehicle - car, boat, or motorcycle - hook a 12v source to the two battery cables and leave it on while the cables are off the battery. More often than not I use a $10 battery charger from a discount store, but anything that will give you 12 volts will be fine. I do this even if I am just doing a quick battery swap. It saves a lot of hassle with the computer and saved radio buttons and a host of other things, and adds about 30 seconds to your workflow.

Better luck next time,

Steve
00 M5
05 X3
10 S1000RR
84 911

[timmay77]

Originally Posted by TurboCarrera

Before I disconnect a battery from a modern vehicle - car, boat, or motorcycle - I hook a 12v source to the two battery cables and leave it on while the cables are off the battery. More often than not I use a $10 battery charger from a discount store, but anything that will give you 12 volts will be fine. I do this even if I am just doing a quick battery swap. It saves a lot of hassle with the computer and saved radio buttons and a host of other things, and adds about 30 seconds to your workflow.

Better luck next time,

Steve
00 M5
05 X3
10 S1000RR
84 911

Dude, we disconnected the battery cables on purpose so the car didn't have power. The way you are SUPPOSE to do it before doing any serious work to keep from frying something. Your advice is appreciated, but does not apply at all to this topic.

[Randy Ray]

May sound dumb but did you try another KEY????
When i bought a dup key from the dealer.....the new key would not work until they recoded it again, and again..........

(I miss the old days when you just hot wired it to help in the diagnosis)


Good luck...it will all work out.


Randy