Multiple warning lights, rough idle, after tailgate wiring fix
 

Hello all, I'm new to the forum and am having issues with my 2010 e61 535i. It's recently received a new battery (registered), and new plugs and coils all around. Car was running great until I decided to fix the severed tailgate wiring looms :bash:. Upon finishing the job, when I start it up, the car now displays the engine, 4x4, and brake malfunction lights on the dash, as well as idles roughly for about 40 seconds before it dies completely. I'm afraid that I've fried some critical module in the car, but I'm not sure where to go from here. DME codes show misfires on cyl 1, 2, and 3.

I've already visually inspected every fuse in both the trunk and glove compartment fuse boxes and they all look good. I've also pulled the DME and, even though I have the MSD81, checked the MOSFETs that were there anyway but they all check out fine.

Any clue how all of these warning lights and misfires are related? Where do I start looking from here? I have a KCAN cable and BMWtools, but am a noob at all of it beyond using INPA to register the battery.

Any insight is appreciated, as I now have a car with working tailgate glass, defroster, and improved key fob range that doesn't frickin drive.

Multiple warning lights, rough idle, after tailgate wiring fix
 

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It all seems like a strange/bizarre coincidence. Have you at least tried to unplug and re-plug your coils and reset the Check engine light? The 4x4 and brake malfunction comes from the battery being disconnected/heavily discharged, you probably already know that you need to drive the car above 20MPH to get rid of those two messages.
This might not help but it is better than silence from the readers ;)

Thanks Pocholin, and I love your car! That's pretty much the stage I want to get mine to once I get it working properly... already have the rear spacers and LED angels, was 1 day away from MHD stage1 ... but I digress.

I've cleared the codes, but the misfires are very real and come back right away. I've read on other forums that misfires can appear in banks of three (1-3, 4-6), so that's what led me to check the MOSFETs in my DME... though, as I have the MSD81 and not the problematic MSD80 on pre-LSI models, it's a different board layout so I'm not certain I tested the correct ones. I just tested those that were available to me under the cover, and they checked out, but there might be some on the back side that I didn't get to. Not sure, didn't dig that deep. I'll try re-seating the coil connections, takes 1 min so what the hell. I've also read that bank misfire issues could be O2 sensor related, but I get no code for bad O2? Those are on the to do list anyway, but the amount of $$$ I'm dumping into this car is getting annoying because...

Battery is brand new (1 month) because I had been getting the "4x4" and "brake" and "excessive battery drain" warnings on startup after the car had been sitting for 3 months while awiting repairs for... drum roll please ... YES! YOU GUESSED IT! ...sucking the serpentine belt into the crankcase through the front oil seal!!! $$$$ I'll save that rant for later. But yes, the old battery was tested weak, and the new battery made those warnings disappear and the car had been rockin' for the last month before I decided to re-loom all of the tailgate wiring. Those warnings might go away after I drive off, but the misfires kill the car, so I can't really test that theory yet.

I guess what I'd really like to know is how to tackle the misfires first. I have the BMWtools software, just don't know how to use it yet or even if it would tell me where to look for issues. It's totally possible that everything together is unrelated, but it all happened on the same startup attempt so just laying out the scenario as it happened for the knowledge-base here.

Thanks all!

When my car had 89k miles the dealer spent a great deal of time fixing misfires on cyl 3 & 6. At the end of about two months of in and out of the dealer they had replaced spark plugs, coils, vacuum test (which they found no leaks), injectors, intake walnut cleaning and finally all four O2 sensors (luckily for me, all under CPO). They did it in that order, using the low-hanging-fruit principle. You might want to do the same...or just go for the O2 sensors...which are expensive.

Nice to get that all covered under warranty!

I dove back into the DME and took apart the daughter board to get access to the components that were previously inaccessible. There were a bunch more transistors under there, but they all checked out fine with my DMM (at least they weren't failed shorted like what happens to the MSD80). Everything you mentioned was on my maintenance list to be done over the next year, so it looks like I have to push that schedule forward significantly :hmm: Walnuts can wait. Already did plugs and coils. Injectors on 3 cyls all at once seems odd... O2/plugged cat theory might be next since it's related to an entire bank (1-3). That's why I'm looking so intently at the DME. My "misfires" are so severe that the car will not run, and it happened all at once. Definitely seems like 3 cylinders are completely non-functional, not just "missing" occasionally. The only other example that I have found online that exactly mirrors my situation was a guy with a 335, and he found his DME at fault.

When you had your misfires, did they render the car unusable, or was it just random roughness and hesitation? And was it the O2s that finally smoothed things out? I trust there was no error code for O2 or they would have started there...

Misfires were only happening at full throttle. Dealer had said that they would've changed the cats before considering the DME module bad. But the DME did come as one of the faulty items.

Cylinders 1,2, and 3 are all part of what's known as Bank 1. It would be very unusual to have 3 different mosfets go bad on the DME, as well as coils, plugs, or injectors.
I'm unsure if the O2 sensor on that bank will cause that issue, especially if it isn't throwing a code, but you might want to look at the catalytic converter downstream. If it's bad internally, falling apart, etc, it can block the exhaust flow and cause those misfires, and it won't typically show a code.

I know this is an old thread but your mention of the rear hatch got me thinking. I had a similar warning light scenario that was brought about by water in the spare tire well. The wagons had problems with both the wire harnesses and the sunroof drains, the latter allowed water to overflow into the spare tire well and swamped out several control modules and relays. It happened to mine and I would crazy random fault codes of different conditions. My Indy diagnosed the problem, cleared the drains, dried out the modules and got everything working again. If you haven't solved it yet, that may be a place to look.