Transmission control Module / TCM ECU suitability

[carrera]

Time to turn my attention to the silver estate car and see if I can rescue that. It's a long preable with a brief question at the end

The car is a 2002MY, B205 E engined auto, Vector trim, 5 speed without flappy paddles for the gearchange and no M selector on the gear selector.

Following this thread I have concluded that the TCM is at fault, P0748. Unfortunately the TCM in the breaker car also throws an error code, P0715.  Having swapped the TCM's over (but no Tech 2 so no reset of saved adaptation) I am happy that the problem and error code transfers with the TCM, so I need another TCM.

This is what I learned from the EPC

It's part number 51 64 256, two plug connections, made by Aisin, and also has the code 93-50 with a GM (not Saab) underline.

2002 model were 5540599, and the replacement is 55352924
2003 model  is simply listed as 55352924
2004-2010 is listed as 55 560 029

I have been doing lots of internet searching and have concluded that the Saab part number is pretty much meaningless, as it never appears on the TCM itself and does not differentiate between engines. Furthermore, the numbers that are shown are not cross referenced to the original Saab part number or car. BUT, with all the searching I have done I have created myself a little database of what TCM part number cross checks to the model year and engine combination - about 50 data sources.

Here's a photo of the original........ there was a very high failure rate on these I understand, the first two digits are always 51 for 2002 TCM's



Everything is clear so far.

From the Saab EPC it seems that the 2003MY TCM's are the approved replacement for the 2002 ones that fail. But are they really ?

I have seen that the 2003MY begin 54 and the 2004MY can begin 54 or 55, the 55 versions seem to be reliable.

From what I understand 2003 was when the flappy paddles were introduced, the gear selector got a M and the dashboard changed accordingly

Was that for all models, or initially just for the Aero with it being an option for other trim level cars ?

Of course, what I really want to know is are the TCM's truly interchangeable, or only interchangeable with Tech 2 software reprogramming ?

I am unable to locate a good TCM for a 2002 car (and if it was good how long would it last now), but have found TCM's from a 2003 B205E and a 2003 B235R. The one off the aero is much cheaper but is marked as having the paddle shift. If I fit that will I get an error code which can be cleared and not return, or will I need a Tech 2 to program it with the different software / change point map for the B205 engine. 

Does anyone know ?

[sgould]

I don't know!

But I know someone who has upgraded a 2002 car to one with flappy paddles and he said it was quite straightforward. Unfortunately I don't know what bits were swapped or used.  So there shouldn't be a lot of difference.  It may actually be the same unit with different software.

[carrera]

I don't know!

Now I don't quite believe that 

I think I saw that thread when I was reading the internet. It involves replacing the TCM, auto shift unit, instruments console and the steering wheel flappy paddle buttons.

It would be good to know if he needed the Tech 2 or as he swapped everything at the same time it all the bits just played nicely with each other when connected. The TCM has no coding / handshaking needs that I can see so they are just plug and play, apart from adaption and software upgrades.

I really need to find a Tech 2 at sensible money 

[sgould]

I'm fairly certain that it was Paul Price - 9000parts on uksaabs.

[carrera]

I'm still reading.......... looks like I was quite close, the instruments and gear selector are optional changes

Different SID too to interpret the paddle shift buttons, an extra wire from SID to TCM (fiddly) and it is Tech 2 that switches the paddle shift on and off



So perhaps the absence of the SID wire and paddle shifts will not cause a problem, the ECU just thinks they have been switched off ??

[phoenix]

My experience... I had an 03 car with paddles that needed a new auto gearbox. I got one from an 04 car (with, as luck turned out, it's TCM).

Having fitted the new box I took it for a test drive and it drove like a dog with flashing autobox error light. I was wondering what I'd done wrong and then I remembered the TCM. Popped the 04 one in and all was good.

02 and 03 part nos are the same, 04 onwards are different so you should be OK with any 02/03 TCM I think.

[carrera]

That's interesting phoenix.

I'm not sure that 02 and 03 TCM's are the same. From my research the numbers on the back of the TCM for a B205E are as follows

2002 - 51 64 256 (from my cars)
2003 - 54 40 326
2004 - 55 90 518

I was going to stick my neck out and suggest what the TCM numbers for your car were, but as I don't know which engine I am saved potential embarrassment.

From what you have said I think we are in agreement that the 2003 TCM is the recommended replacement for the 2002 one. Subject to paddle shift and Tech 2 complications ?




 

[phoenix]

Before the MY02 onwards 5 speed, there were individual TCMs for different boxes. Thereafter it was the same. However installation requires programming with the specific version of SW appropriate to the engine. My copy of EPC lists

MY02: 54 04 599 NLS use 55  352 924
MY03: 55 352 924
MY04-: 55 560 029

However I can't find any of the part nos you list in EPC but they can be found by Googling, which suggests that from the factory there were indeed different part nos but any replacement was specifically programmed to the individual car.

For interest here's the list for all the pre 02 models which gives an idea of why they would want to go the above way:

45 78 597 Transmission control module 1998, B205E 1
49 26 515 Transmission control module 1999-2000, B205E 1
51 64 298 Transmission control module 2001, B205E 1
45 79 280 Transmission control module 1998, B235E 1
49 26 523 Transmission control module 1999, B235E 1
45 79 280 Transmission control module 1999, B235E, LHD, CA, US 1 Note: Ch. --X3020000
49 26 523 Transmission control module 1999, B235E, LHD, CA, US 1Note: Ch. X3020001--
52 56 631 Transmission control module 2000, B235E 1
51 64 330 Transmission control module 2001, B235E 1
52 56 649 Transmission control module 2000, B235R 1
52 52 945 Transmission control module 2001, B235R 1
45 78 571 Transmission control module 1998, B308E 1
49 26 531 Transmission control module 1999-2000, B308E 1 Note: Ch. --Y3040000
45 78 571 Transmission control module 1999, B308E, LHD, CA, US 1 Note: Ch. --X3020000
49 26 531 Transmission control module 1999-2000, B308E, LHD, CA, US 1 Note: Ch. X3020001-- Ch. --Y3040000
51 60 007 Transmission control module 2000, B308E 1 Note: Ch. Y3040001--
52 56 862 Transmission control module 2001, B308E

[carrera]

Agreed (except I think you have transposed digits 3 and 4, and that's what I included as a quote in the first post.

The mind bending bit is that the numbers on the back of the TCM are not Saab part numbers but Aisan part numbers (the top number) or software revision (the bottom pair of numbers) which is pretty much a guess on my part, but there is no pattern to the changes by year on these numbers, no apparent version increment. The 2002 ones I have say 93-50, 2003 ones are 09-06 or 08-05 for petrol or 02-02 for diesel.

The similarity between the part numbers threw me at first, but if you notice the 2002 EPC Saab number is 7 digits, and the 2003 on are 8 digits. The big number on the back of the TCM are always 7 digits long and the confusion is further amplified because the 2003 Saab number begins with 54, the same two digits as the 2002 Saab number. 

[carrera]

...and here's my current version of all the combinations I have seen from various sites and ebay descriptions. I would not say it is perfect or definitive, as I am relying on other peoples information, but it has been a useful help for me

[carrera]

So I have been exercising my brain cell this morning and have downloaded the 2002 and 2003 owners manuals.

According to this it appears that all MY2003 models did have sentronic, as there is no mention of trim levels. I did see something in one post that suggested that sentronic was not fitted on early MY2003 cars, perhaps that was incorrect.

That sort of adds a bit more knowledge, but I am still guided towards the idea that the 2003 TCM's are useable in 2002 cars, but only because of the replacement part number shown in EPC.

Here's the important pages, which show the changes in the shifter and the instruments

[phoenix]

My understanding is that Sentronic became standard for MY03 models onwards, which were introduced in Sept 02. The MY02 models were "regular" 5 speed auto.

[carrera]

Somewhat of a success today   

The replacement TCM arrived, from a 2003 with Sensonic / flappy paddle capability. Sgould had introduced me earlier this week to JTC (a new member on here who he knew was local to me) who has Tech 2 and so we spent the afternoon trying to get things working.

The first thing we did we confirm what error codes came up with the different TCM modules, being original, breaker and 2003 Aero. The starting assumption was that both TCM's I already had were faulty.

original had P0748
breaker had p0717 (this was different to my generic reader which showed p0715)

Then we put the aero TCM in and got two error codes, p0717 and p0826 which was a new one related to the absence of the sensonic signal from the SID (2003 cars have an additional wire).

After messing around with clearing adaption data and error codes on various modules, it slowly dawned that we had two TCM's which showed the same error code. We were unable to find a way to disable the aero TCM from expecting to see the sensonic signal (though it must be possible otherwise how do Saab use the later modules, perhaps it's through replacement of the software ??) so we decided to put the breaker TCM and follow the diagnosis procedures.

P0717 is an error code because of a missing signal from one of the two speed gearbox speed sensors on the box. This is compared to the trionic rpm signal, and if they don't agree the error is thrown. Now, having a spare gearbox meant it would be easy to replace the sensors one at a time to see if the problem was cured.

The first one we replaced was the output shaft which is easily accessible towards the rear of the box. No change. the input shaft sensor is below the battery box, the the battery tray was removed along with the 10mm bolt that holds the sensor.  With the bolt out I went to remove the sensor, and as I twisted it I realised the electrical connector was not in place. 

So, the retaining bolt was put back, connector inserted, battery pack on and the engine fired up. The error code was cleared, the banging on gearshifts when stationery were gone and the gearbox input shaft speed read using Tech 2.

So everything is hunky dory and the diagnosis of a failed TCM was confirmed to be correct.

In a way I am kicking myself, because the speed sensor error was being flagged up with my generic OBD reader, but that code does not exist in Saabworld. More than that, the original TCM did not report a problem with the input speed sensor, so I'm not being too hard on myself.

So, big big thanks to JTC for his help and assistance this afternoon with Tech2 , we had a really good chat and a fair bit of coffee 

I know a lot more about Saab auto boxes and TCM's than I ever expected to know too 


   

[sgould]

Glad it all worked out!

JTC is a useful chap to know!

[JTC]

Bit of a trial but we got there in the end 😁