Transmission 8HP45 Swap and Mechatronics Question
 

Hello all. I would appreciate some insight/suggestions on a transmission issue I’m having.

Background: I purchased a BMW X5 35i with a bad transmission. It has the ZF 8HP45 transmission. When I pulled the pan I found chunks of metal in the pan, so I bought a replacement transmission from a donor 2011 X5.

After I replaced the transmission I couldn’t get the transmission to shift out of park (no reverse, neutral, or drive). I read that the transmission control module (Mechatronics) is mated with the DME, CAS/FEM/BDC modules for the specific vehicle. Thus, when a transmission replacement is required, it is not possible to install a used automatic transmission without affecting the ability of the vehicle to function.

So, I thought, no problem. I dropped the pan and valve body from the “new” transmission and swapped the mechatronics from the original valve body onto the new valve body. I re-installed the new valve body with the old (vehicle's original) mechatronics, re-installed the pan, filled it with fluid, and then: same thing. The vehicle will not shift out of park. I don’t have any transmission codes (or at least I don't think I do as none show up on my Autel scanner). I am getting a transfer case code, however. The transfer case code is: CF80 - signal from engine management setpoint-torque request. I think this code would go away once the car is moving again but I don’t know. Regardless of this code, I would think the transmission (separate from the transfer case) would still select a gear.

Here’s my main question: Did starting the car with a different mechatronics (the one that came with the “new” transmission) than the original one cause the DME to freak out and now it won’t even accept the original one?

I’d like to hear some suggestions from you all before I ship a mechatronics unit to be “virginized” at a cost of $300 if that’s not my problem.

I’ve posted in E46 Fanatics as I own a 2004 325i, but this is my first post in xoutpost.
Thanks in advance for any advice you might have.

That sounds very plausible. Hopefully someone with more knowledge about swapping modules will chime in.

Long shot but have you tried to disconnect the battery overnight? This rarely works for anything on a BMW but in this case, it is worth a try. Do you have a OBD to USB cable? ISTA+ software may get you better codes and diagnostics.

https://www.bimmerfest.com/forums/sh....php?t=1023698

Thanks for chiming in crystalworks and smassey321.

I'll disconnect the battery for a few days (working nightshifts and won't be able to mess with it again for a few days anyway).

smassey321, I have a OBD2 to USB cable, but I used it for VAGCOM. I'm not sure if it works for BMW as well. Do you have one that you recommend? I also don't have ISTA software. A trip to a local BMW independent mechanic with the proper software might be in my future.

Vagcom cable is not the same is what your BMW needs. This is what most people use. https://www.bimmergeeks.net/product-...eeks-pro-cable

Did you "fill" the trans with fluid, or go through the proper refill procedure (with the vehicle running & at operating temp)?

It was filled the proper way.

UPDATE:

I have been doing lots or research on this. Only E70 (X5) and E71 (X6) models came with EWS security in E series. EWS essentially immobilizes the vehicle. In my original post in this thread, when I said “cause the DME to freak out”, what I think really happened in technical terms is I activated the EWS. Even with the original mechatronics back in, the EWS is active and needs reset/cleared. Here is my plan:

1) I have a K+Dcan cable on the way and I’ll install Standard Tool (INPA, NCS, etc) from Bimmergeeks(DOT)com. I’ll read all codes and clear them all and re-try.

If that doesn’t work, then:

2) I had posed this same question to bimmerscan(DOT)com I received a reply that (he thinks) all I need to do re-code the EGS. I’ll try that.

If that doesn’t work, then:

3) I’ll need to find a shop/person/whatever that has ISTA/P or AutoHex to reset the EWS

References:
https://www.microtronik.com/support/...ynchronization

BMW Coding Forum

I will figure this out and I promise I’ll post the resolution once I figure it out.

SOLVED
 

SOLVED

To recap, it wouldn't shift into any gear once I replaced the transmission with the mechatronics from the replacement transmission still in. Even with the original mechatronics back in, it wouldn't shift into any gear.

So, I did end up tripping the security (immobilizer) by starting it (powering it up) with the foreign mechatronics.

With the original mechatronics in, all it took was the K+Dcan cable and ISTA. I read the codes and cleared all fault memory. That's all it took. Took it for a drive today!

Awesome. Thanks for the update.