[bmchicago]

no faults in transmission and shifts to park on a Gen1 6HP? this is usually caused by too high voltage or not enough fluid.

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I checked door status in the CAS and found the passenger rear door was "status 3" rather than reporting open or closed. Replacing a fuse now has all doors accurately reporting closed status, but transmission problem persists. I have a seatbelt warning and a misfire that I'll chase next.

you have a seat belt warning? is it for the drivers seat??

[Beard]

I checked door status in the CAS and found the passenger rear door was "status 3" rather than reporting open or closed. Replacing a fuse now has all doors accurately reporting closed status, but transmission problem persists. I have a seatbelt warning and a misfire that I'll chase next.

Hello.
First we need to solve the problem with the engine.
The engine must not have any malfunctions.
There is no gearbox without an engine. The engine sets it in motion.

[RocketSurgeon]

no faults in transmission and shifts to park on a Gen1 6HP? this is usually caused by too high voltage or not enough fluid.

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I checked door status in the CAS and found the passenger rear door was "status 3" rather than reporting open or closed. Replacing a fuse now has all doors accurately reporting closed status, but transmission problem persists. I have a seatbelt warning and a misfire that I'll chase next.

you have a seat belt warning? is it for the drivers seat??

The seat belt light is on, but the car is correctly detecting the driver and passenger seat belt latching based on live data.

Running voltage is nice and healthy around 14v. Fluid level is correct. I wish I could find a way to read line pressure in the data.

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Here are the current codes.
   

[Node]

So now we learn that no comms with door module is not the only fault... Of course seat belt sign is also suspicious, but given your EMF is stuck, reports undervoltage and is connected directly to PT-CAN I would suggest you try to disconnect that unit as that is quite easy to do.

From your description we are chasing some transient fault here, not static one like seat belt would be.

[jaki]

In mysterious cases, I allways do complete car flash with AOS ISTA.
That clears if son
me modules s/w is corrupted in somehow.

[bmchicago]

I suspect the fluid is not full. your filling it correctly with the engine running and adding fluid to the fill plug and not through the drain plug?

[PelsonBMW]

For me it's a problem with seat belt/door lock

[RocketSurgeon]

So now we learn that no comms with door module is not the only fault... Of course seat belt sign is also suspicious, but given your EMF is stuck, reports undervoltage and is connected directly to PT-CAN I would suggest you try to disconnect that unit as that is quite easy to do.

From your description we are chasing some transient fault here, not static one like seat belt would be.

I did an i-step on the car and replaced a few fuses, which seems to have fixed all of the door module and airbag codes, alongnwith the seat belt light. I disconnected the EMF, but it's still doing the same thing. I also took off the belt to rule out alternator. The gear position lights begin to blink within about 5 seconds of starting the engine, so that's interesting.

In mysterious cases, I allways do complete car flash with AOS ISTA.
That clears if son
me modules s/w is corrupted in somehow.

A software update did fix all of the door module and airbag communication issue, but transmission issue remains

I suspect the fluid is not full. your filling it correctly with the engine running and adding fluid to the fill plug and not through the drain plug?

Filled while running and level, after cycling through gears.

For me it's a problem with seat belt/door lock

After a software update, all of those issues appear to be resolved. Here are the new codes.
   

[Node]

So your EMF is still stuck?

However those blinking lights sound suspicious. How do they blink? Is it like random gear being displayed? Or just the number blinks?

Depending on blinking mode:
Have you checked EGS is getting proper 12V power/ground and PT-CAN signals are clean? Also 15-WUP signal. 
Was gear blinking the same with disconnected alternator?
Also gear selector lever could have failed if you are getting random gears. I would try to disconnect EGS wire between EGS & SZL.

[RocketSurgeon]

So your EMF is still stuck?

However those blinking lights sound suspicious. How do they blink? Is it like random gear being displayed? Or just the number blinks?

Depending on blinking mode:
Have you checked EGS is getting proper 12V power/ground and PT-CAN signals are clean? Also 15-WUP signal. 
Was gear blinking the same with disconnected alternator?
Also gear selector lever could have failed if you are getting random gears. I would try to disconnect EGS wire between EGS & SZL.

The EMF seems to be broken, but the parking brake is not applied, so the car can roll freely.

The gear indicator blinking is somewhat rhythmic, not like a random glitch or flicker. It did the same with belt removed. The blinking RND seems like the transmission indicating a fault condition despite the lack of codes. The power, ground, and KL15_WUP to the transmission are clean. I can't vouch for the PT-Can though without an oscilloscope. I watched live data in the SZL while manipulating the gear selector, and it consistently displays every action accurately. 

I just discovered that my local parts supplier gave me aftermarket seals and transmission pan, so that may also be a possibility.