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98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

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CIK7
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98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by CIK7 » Thu Mar 26, 2020 12:34 pm

I have 2 98 XC, 1 in white seems fresher- junk car, 1 in black- my daily driver. The junk white has a 35.3 Aisin transmission computer; black one has a 44.3. I tried typing in those numbers. Nothing *shrugs* comes up. Is the 44.3 better than 35.3? Can I switch them? Advantages disadvantages? I assume the 44.3 is an updated module?
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1998 V70 XC black ($1K trade, Mi:144/147K, immaculate, remodel in progress, 2 updates coming soon)
1998 V70 XC white ($50 cash, junk, donor for my black XC, off to jy soon, PM for parts)
2001 V70 Ba white (sold)
2009 Impala LT 3.5L (sold)

Plans for my 98 XC: 16T/18T, P2 M66 swap, logo/badge delete excl grille

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Re: 98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by abscate » Thu Mar 26, 2020 1:05 pm

You need software to read what/has/hasnt been done to the controllers.

This is not a good place to play - there is no magical computer that will bolt on HP, and you can get in a world of hurt if you brick something
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Re: 98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by misha » Thu Mar 26, 2020 4:46 pm

General rule is...the numbers from original TCM needs to be exactly the same on the replacement TCM,excluding serial numbers.

In your case....TCMs have different part numbers and different software numbers.
One is from '97 the other one is from '98(according to serial number).

I would not try to swap them separately.
If you're gonna swap them...swap them both...along with matched ECU.

According to the picture...ECUs have the same part numbers but different software numbers(probably emissions differencies) and there is possibility that you will have a CEL on with replacement ECU.
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'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
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Re: 98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by CIK7 » Thu Mar 26, 2020 5:37 pm

misha wrote:
Thu Mar 26, 2020 4:46 pm
General rule is...the numbers from original TCM needs to be exactly the same on the replacement TCM,excluding serial numbers.

In your case....TCMs have different part numbers and different software numbers.
One is from '97 the other one is from '98(according to serial number).

I would not try to swap them separately.
If you're gonna swap them...swap them both...along with matched ECU.

According to the picture...ECUs have the same part numbers but different software numbers(probably emissions differencies) and there is possibility that you will have a CEL on with replacement ECU.
Which one is for a 97? Both of those cars are 98.
1998 V70 XC black ($1K trade, Mi:144/147K, immaculate, remodel in progress, 2 updates coming soon)
1998 V70 XC white ($50 cash, junk, donor for my black XC, off to jy soon, PM for parts)
2001 V70 Ba white (sold)
2009 Impala LT 3.5L (sold)

Plans for my 98 XC: 16T/18T, P2 M66 swap, logo/badge delete excl grille

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Re: 98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by misha » Thu Mar 26, 2020 5:58 pm

Under the last barcode ...T97 and T98.
It looks that both TCMs are from '97 i must had been oversight the numbers.

TCM from the 1st picture doesn't match the ECU...or...ECU doesn't match TCM.

One of those had been replaced in the past.
Both should be from the same year.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
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'71 144 S
'73 144 De Luxe
'78 244 DL
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Re: 98 XC: 2 cars, same year and trim, different transmission computers-interchangeable?

Post by Sommerfeldt » Sat Mar 28, 2020 8:48 am

misha wrote:
Thu Mar 26, 2020 5:58 pm
TCM from the 1st picture doesn't match the ECU...or...ECU doesn't match TCM.
How would you "match" the ECU and TCM? There's no guarantee that all parts are from the same year. My T5 had parts made late 1994, all the way to '96.

OP doesn't need to worry what ECU is in the car. The issue is making sure the gearbox itself is the same - IIRC there are 2 different ones for the 1st gens? In this case, seems to me that they're both for the AW50-42LE, The "44.3" seems to have been exclusively used on the 2.5T, but can't say for sure.

There shouldn't be an issue interchanging these. But, without knowing what exactly was done to it, there's no guarantee that it won't do weird things. Unless you're having issues with the gearbox, there's no need to mess with it. I've done a lot of strange stuff to 850s, but never had either a need or a desire to mess with the gearbox stuff. :)

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