BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > DIY: Mechatronic seals and gear selector rod - GM GA6L45R

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      02-08-2016, 03:29 PM   #1
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DIY: Mechatronic seals and gear selector rod - GM GA6L45R

I wanted to consolidate the info on replacing the transmission selector rod and Mechatronic seals/sealing sleeve for the GM GA6L45R transmission, as I found various information in various places, and wanted to add a few helpful details left out of what I found. Fairly easy, albeit messy fix. $325 in parts and fluid roughly.

This is my experience, and any information here is to be used at your own risk. As always with the DIY guides, I assume no responsibility for anyone undertaking this repair.

My primary resource was the Bavarian Auto/Bentley procedure.

This sealing sleeve document was a huge help, as well.

A few notes:

1. Disconnect the battery.

2. The electrical connector at the back of the Mechatronic unit is a white/beige tab that pulls straight down. There is another one that is internal to the Mech unit that is in the front that stays connected.

3. There is a risk of ESD discharge if you touch the Mechatronic pins. Fingers out!!!

4. The vertical transmission switch tab goes in the V slot of the selector rod. When you put the Mechatronic unit back, the steel pin on the notched gearshift cam needs to line up in the same V slot (gearshift in Park and the transmission switch fully forward.) See pic.

5. Taking the transfer case/exhaust bracket makes getting to the sealing sleeve at the back of the transmission a lot easier. HOWEVER!!! It really helps to put the bracket back on before you put the transmission pan back on. I did not do this, and you can't get a socket on either transfer case bolt, and the bolt closest to the drain plug is very difficult to even get started. Needle-nosed pliers, small Vise-Grips, and E12 GearWrench to the rescue.

6. Put the Mechatronic unit back in very gently and make sure the sealing sleeve isn't getting pushed out of the back of the transmission. Line up the sealing sleeve tab w/ the Mechatronic slot. Don't force anything.

7. I never found torque specs for the Mechatronic bolts for the GM trans. I used common sense here and just made sure everything was tight.

8. The Mechatronic electrical connector, again, needs to be very gently lined up and locked in place. If both the pins and the locking collar are not lined up it won't let you lock the connection properly.

9. Once the Mechatronic unit is back in, connect the battery and run codes. If anything isn't fully connected, you should find out before you get carried away with fluid. Obviously, DO NOT START THE CAR.

10. Ignition on, foot on brake, again DO NOT START THE CAR. Make sure you can shift between Park and Drive a few times, and that the dash display shows the correct gear. I believe if the pins are not seated properly it trips the interlock solenoid on the gearshift, as this happened to me and I was stuck in Park. In essence I did this repair twice. Run codes again.

11. On AWD models at least, I got the AWD/DSC disabled error which apparently happens when you disconnect the battery. This is reset by turning the steering wheel all the way in both directions to reset the Steering Angle sensor. I also got the Drive-off Assist Inactive error. Again, I think this was just needing to be reset along with the AWD/DSC error.

12. Fluid fill. Plenty of info out there on this.

13. Reset transmission adaptations. Again, plenty of info out there on this.

14. Good luck! Hopefully I can save someone the time I spent sorting out a few issues before being able to know it was installed properly.
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      08-12-2018, 12:05 PM   #2
ryan stewart

Drives: 2008 328it
Join Date: Aug 2012
Location: Atlanta, GA

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Hey to add do this, not sure if they were posted but some videos I found that I thought I should link for reference.

Its a transmission repair guy doing a full teardown of our transmission AND replacing these valves, the entire video.

Full teardown

Diagnosis and showing the parts and replacement:

he also mentions wiping metal off of that selector guide for the sake of the magnetic sensors.
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