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Noob Zone => Noob Questions => Topic started by: horon6155 on June 28, 2025, 12:56:42 PM



Title: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 28, 2025, 12:56:42 PM
Hello, Leuye. I installed a DQ250 from a MK5 GTI in my Golf MK4. I got the transmission very cheaply and now I know why.

At first, everything worked when it was cold. As soon as the transmission warms up, nothing works anymore. The lights flash. I then replaced all the selenoids and solenoid valves. It's much more pleasant when it shifts into R or D, but as soon as it warms up, the same thing happens again. Error codes 1815 and 1820. I then replaced the pressure sensors and changed the oil again.

Now the same thing isn't happening. When I put the car in D while it's warm and accelerate, D starts flashing. As soon as I idle, it stops. Same thing with R. I then tried to do the basic settings, and since then I've been getting the error P1707 and everything is flashing again.

I can't read the TCU with Autotuner or KESS3 either. I get errors.
I think the TCU is defective.

I want to get a new one, but they're extremely expensive. I thought I'd buy a DQ250 TDI transmission and simply transfer the TCU and install MK5 GTI software on it. Would that work, or are the mechatronics different?


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: _nameless on June 28, 2025, 09:16:51 PM
Where are you located? I have a few mech units just chillin


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 29, 2025, 03:44:44 AM
I'm from Germany. What would you like for them? Are they functionally OK?


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: _nameless on June 29, 2025, 01:02:34 PM
I'm from Germany. What would you like for them? Are they functionally OK?
Yeah Im in the states though. I have a few sitting in the trans still I can pull if needed


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 29, 2025, 03:14:19 PM
Are they ones from the Golf MK5 GTI, or do all 02e TCUS fit together? Which one would you like?


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: aef on June 30, 2025, 07:05:32 AM
try to source a exx or fxx mechatronic instead of the old mk5 cxx mechatronic

Quote
Here some informations about 02E Hardware Numbers assignment:

GROUP "Cxx"   EARLY UNITS all with analog inputs (for speed signal, shift paddles or reverse light control) (used moslty 2003-2004 some of them have additional pins in connector

02E927770 E
02E927770 G
02E927770 K
02E927770 L
02E927770 M
02E927770 AA

GROUP "Cxx"   (2004 - 2006)

02E927770 AD  - replaces all EARLY analog units because can EMULATE analog inputs.
02E927770 AE  - used only on cars from year 2004 which DO NOT use analog signals anymore.

GROUP "Exx"  (2007 - 2008)

02E927770  AJ  - used as replacement for AE, CAN only, no K-Line anymore.
02E927770 AK  - no information nor experiences til now. Very rare unit.

GROUP "Fxx"  (2008 - 2015)

02E927770 AL - replacement for AE, AJ
02E927770 AM - theoretically can be used on some cars which still needs AD, but special software versions are required.
02E927770 AT - replace AL

IMMOBILIZED UNITS used on MQB cars with UDS diagnostic protokoll.
Cannot replace NON-IMMO units, because of bootloader incompability.
02E927770 AN
02E927770 AQ
02E927770 AS


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 30, 2025, 09:15:13 AM
And why? Are the exx or fxx better than the cxx? I don't even know which one I have. In any case, I know that the cxx has more pins, but mine only has the necessary pins for power, ground, can, and k-line, and two other pins, if I'm not mistaken. Actually, a cxx would be better for my golf mk4, if it fits, because it has a reverse gear signal, so I don't have to build a separate controller for it.


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: aef on June 30, 2025, 01:09:23 PM
its gambling.... you can buy another old cxx with more or less problems

or you can buy one of the latest fxx or mqb with less mileage


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 30, 2025, 01:54:19 PM
Since the nameless guy isn't responding anymore, I'd like to return to my other question.

Can I use a 2.0 TDI TCU for my GTI transmission and install GTI software on it?


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: _nameless on June 30, 2025, 04:53:44 PM
Are they ones from the Golf MK5 GTI, or do all 02e TCUS fit together? Which one would you like?
Yeah its from a mk5.
Since the nameless guy isn't responding anymore, I'd like to return to my other question....
LOL sorry I have a life outside this thread.


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on June 30, 2025, 11:39:07 PM
I'm sorry, I didn't mean to offend you. Please don't misunderstand me. What kind of functioning TCU do you want? Ideally, an FXX TCU?


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: _nameless on July 01, 2025, 01:32:40 AM
I'm sorry, I didn't mean to offend you. Please don't misunderstand me. What kind of functioning TCU do you want? Ideally, an FXX TCU?
The ones I have are CXX versions


Title: Re: 1.8t DQ250 conversation TCU Problem
Post by: horon6155 on July 02, 2025, 03:10:41 PM
Hi. How much do you want for a mechatronics unit?