335i single turbo transmission issue

SlowE92 · 10-12-2024, 06:41 PM

Im at my wits end with this car. I replaced the entire transmission and the shifter, as well as the shifter cable. Whenever i put the car into drive it engages M2. When i put it into sport mode it will show the D/S but will not leave 2nd gear and doesnt shift. I replaced both paddles as well. The car has a jb4 and a Custom MHD BEF for a borgwarner 6973. Im thinking i replaced all hardware then it mist be a software issue but there are no codes. But i occadionally get the transmission malfunction light on the dash so if anyone has any tips or can help i would greatly appreciate it.

konstat · 10-13-2024, 06:34 AM

What’s the code when the transmission light comes on? Only thing I can think of is a faulty TCM. Did you at some point ever accidentally touch the pins on the TCM? They’re prone to failure from ESD.

Do you have an xHP flash? If so, is the issue still there when you completely uninstall the flash?

Also, how new is your valve body? Did you swap in your old valve body to the new transmission? I’m assuming we’re talking about a 6HP21

SlowE92 · 10-13-2024, 07:27 PM

Quote:

Originally Posted by konstat

What’s the code when the transmission light comes on? Only thing I can think of is a faulty TCM. Did you at some point ever accidentally touch the pins on the TCM? They’re prone to failure from ESD.

Do you have an xHP flash? If so, is the issue still there when you completely uninstall the flash?

Also, how new is your valve body? Did you swap in your old valve body to the new transmission? I’m assuming we’re talking about a 6HP21

New valve body, bought it with the new transmission from a bmw dealership. There isnt any codes, just the downpipes. I think however that i cant read the codes with just a normal obd2 or the mhd app, or read them through the jb4 app. And no i dont have an xhp flash anymore, i took it off when coding the new transmission. Its a 6hp21

konstat · 10-13-2024, 07:59 PM

We’re talking on two different threads but we can continue for continuity. You can purchase protool from bimmergeeks to see codes from each module. $70 for the diagnostics software I believe.

10-12-2024, 06:41 PM	#1
SlowE92 First Lieutenant 115 Rep 369 Posts Drives: E92 2007 335i, E60 2008 535xi Join Date: Sep 2023 Location: Salt Lake iTrader: (0)	335i single turbo transmission issue Im at my wits end with this car. I replaced the entire transmission and the shifter, as well as the shifter cable. Whenever i put the car into drive it engages M2. When i put it into sport mode it will show the D/S but will not leave 2nd gear and doesnt shift. I replaced both paddles as well. The car has a jb4 and a Custom MHD BEF for a borgwarner 6973. Im thinking i replaced all hardware then it mist be a software issue but there are no codes. But i occadionally get the transmission malfunction light on the dash so if anyone has any tips or can help i would greatly appreciate it. __________________ 2007 E92 335i - MHD, Turbo Technics 19T's 2008 E60 535XI - JB4 2010 E92 335i - JB4, Borg Warner EFR 8374
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10-13-2024, 06:34 AM	#2
konstat Enlisted Member 21 Rep 37 Posts Drives: 2008 135i M Sport Join Date: Oct 2024 Location: Massachusetts iTrader: (0)	What’s the code when the transmission light comes on? Only thing I can think of is a faulty TCM. Did you at some point ever accidentally touch the pins on the TCM? They’re prone to failure from ESD. Do you have an xHP flash? If so, is the issue still there when you completely uninstall the flash? Also, how new is your valve body? Did you swap in your old valve body to the new transmission? I’m assuming we’re talking about a 6HP21 Last edited by konstat; 10-13-2024 at 06:35 AM..
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10-13-2024, 07:59 PM	#4
konstat Enlisted Member 21 Rep 37 Posts Drives: 2008 135i M Sport Join Date: Oct 2024 Location: Massachusetts iTrader: (0)	We’re talking on two different threads but we can continue for continuity. You can purchase protool from bimmergeeks to see codes from each module. $70 for the diagnostics software I believe.
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