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Transmission Failsafe Mode w/ Transmission Code 15

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I recently had my mechanic replace the transmission in my 2001 540iT Sport Wagon based on the diagnosis from Concord BMW. When it was installed, the car dropped into the Transmission Failsafe Program mode and displayed transmission code 15: Pressure actuator failure. This is also generic OBD II code 1748: Manufacturer Transmission Control Unit Malfunction and/or Transmission Control Unit Self Test Failure.
Has anyone experienced this problem? If so, what was the diagnosis?

My mechanic doesn't have the big BMW test set to fully diagnose this issue so I've made an appointment to take the car to Concord BMW for diagnosis.

I also had the transmission control module replaced and reprogrammed. Does anyone know if the transmission failsafe program cuts out a lot of the transmission control module functions?

First off, the shift selector indicator on the dashboard is disabled. According to the service manual, the LEDs are enabled through the TCM. Also, the shift lock solenoid is not operating. I can put the car in any gear without having to depress the brake. The pathway for this circuit also travels through the TCM. Unfortunately I do not remember if those two items worked before I had the transmission replaced.
The sport mode is unavailable and no indicator lights change when I tap the shifter to the left.
Additionally, the parking control assist does not activate when the vehicle is placed in R (possibly indicating an electrical problem vice a hydraulic/mechanical problem with the transmission).

I am trying to avoid another R/R of the transmission and was wondering if it could be the computer interface inside the transmission? If so, can that be replaced? I have verified continuity between the TCM and transmission connector and a visual inspection of the connector pins does not indicate any damage/missing pins.

Even though the car is sluggish from the start (because it is stuck in 4th gear), it drives great.

The last time I had the transmission diagnosed by the dealership, 20 minutes later they said, "We couldn't see anything wrong specifically, BUT you need to replace the transmission." $6000.00 later, I now have a working transmission but I am still having issues. Any input to help isolate the issue BEFORE I take it back to the dealership for their input would be greatly appreciated.

2001 BMW 540iT Sprot Wagon w/ Steptronic 5 speed
ZF transmission part# 5HP24A
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How do you read the transmission error codes? I have the Pieke tool and I was testing my transmission shifts and it went into failsafe but I couldn't get any codes out of the Pieke (just got the "---")
In the morning and when the car is really cold it shifts crappy. It either bangs into gear, looses power while turning and accelerating. When I shift manually it seems to act a lot better. When the car is warmed up it seems to act a lot better.

When I took it out at lunch (cold) I was doing some testing. I turned off the DSC and did a hard launch in automatic - sport mode. It felt like a slipping clutch going into gears and then going into 4th the Transmission Failsafe light came on. I was kind or relieved to at least know I wasn't crazy and would have some codes to work with.

I got home. Turned the engine off. Inserted the Pieke tool. Then turned the key on. Then pressed Go. No codes "--". Nothing.

Turned the car on. No Transmission Failsafe. Drove around. Car drove perfectly fine. Tried to repeat the transmission failsafe and couldn't do it. Very frustrating!

Now I have been getting some weird electrical things lately. I had 3 of my 4 new Angel Eye rings light up and the 4th would come on later. Re wired the whole thing and didn't help. Bumped up the fuse and that helped 100%.

Then the brand new battery dies on me 2 days ago. Ordered the FSU for replacement and charged it over night but no problems.

Then I started the car after work yesterday and the flashers and the dome light came on - on their own.

So it could be alternator, new battery is bad, VW MAF unit doesn't work I just put in, did something wrong when doing the tranny fluid, etc etc etc.


Guess I will have to watch, wait, and see.
OK - here is an update on my condition. Took my car to AutoZone to have the new battery checked and the alternator checked. Still planning on re-checking the tranny fluid level too but this was an easy place to start.

First the battery. It was very low despite being charged all night. It read "charge and retest". It did fine under load.

Then the alternator. Got in and held 2000 RPMs. I was 100% prepared for it to be bad. Guess what - it tested OK. I don't know how long this thing will last but that was some good news. During the test the tech noticed as the revs fell to idle the voltage dropped too. He then suspected the battery was bad. We grabbed a new one and then retested and sure enough the voltage remained constant and didn't drop off with load. Kept the new battery and drove around. Didn't seem to be any problems with shifting. No mystery lights coming on.

Next day - fire up the car and drive off. It is wet from rain and a LOT warmer then usual but the car behaved 100% better. The car always seems to be perfect in manual shifting mode - it is just when in normal driving mode when I head out in the morning that it seems to loose power upshifting, hunt for the right gear (feels like slipping clutch) and then bangs into gear sending the car forward.

I will keep testing but maybe this was an electrical gremlin. I will still use the Bentley to recheck my fluid level on the rack this weekend as well.
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