Gearbox TCU

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
Frazz82
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Gearbox TCU

Post by Frazz82 » Fri Nov 17, 2023 10:02 pm

Can you get the gearbox mapped on a car running standard BHP ?

An is the map done through the TCU. I am trying to cure 2 codes I get that are 18223 and 18243 if the TCU is faulty was going to either get it repaired or buy another an get it mapped.

Would it improve the shifting and are there any negatives as I dont want to put any extra strain on.the chocolate gearbox

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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sat Nov 18, 2023 10:16 am

You can. There's not much to be gained. The shift points can be changed slightly, if that's something you want. On mine, the MTM TCU keeps the torque converter locked on throttle lift off which gives engine braking, which is nice. I wouldn't be without that now.

There are no negatives really, other than it might not be a good use of money if you're not mapped.

Your error codes relate to short circuits in some of the solenoids. What have you done to eliminate other causes than the TCU?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Frazz82
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Re: Gearbox TCU

Post by Frazz82 » Sat Nov 18, 2023 11:09 am

Replaced the harness in the gearbox so far.

Its odd as u start it straight away it won't show fault codes but turn it on leave it then start it will. This all started happening when my bonnet grommet leaked into car an it was soaking.

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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sat Nov 18, 2023 12:10 pm

Sounds like the TCU might have got wet then.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Frazz82
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Re: Gearbox TCU

Post by Frazz82 » Sat Nov 18, 2023 1:53 pm

I did dry it out at the time. I ve just checked again an its bone dry under there now but taken it out an left it by the log burner just incase.

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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sat Nov 18, 2023 2:43 pm

I repaired a waterlogged ECU in a friend’s D2 S8 once. It was a Hail Mary job. Worked though. Had to reflow the solder joints and that did the trick.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Frazz82
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Re: Gearbox TCU

Post by Frazz82 » Sun Jan 28, 2024 5:49 pm

I ve taken the top of the TCU an looked inside and some of the solder joints are orange ish in colour so think this could be the issue as the faults codes that appeared are around the same time I had a water leak through the bonnet cable grommet.

I ve take some pics of the orange joints.
Attachments
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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sun Jan 28, 2024 6:28 pm

Yeah, looks a bit corroded. But more importantly, those joints are cracked. You can clearly see.
PCB.jpg
Last edited by Shoppinit on Sun Jan 28, 2024 6:37 pm, edited 1 time in total.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sun Jan 28, 2024 6:37 pm

Don't think it's corrosion, on second thoughts. Just looks like localised build-up of conformal coating, but it could also be flux residue, which can be corrosive. Some factories are better than other at cleaning it off. Those big pads just look like radiators.

Get a 20x jeweller magnifier and check all the solder joints.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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TechNick
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Re: Gearbox TCU

Post by TechNick » Sun Jan 28, 2024 8:00 pm

Reminds me of the issue found on my spare TCU... surprisingly, it still worked fine, though!
(Pic taken just before I soldered replacement capacitors in)Image

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Shoppinit
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Re: Gearbox TCU

Post by Shoppinit » Sun Jan 28, 2024 8:04 pm

Mmm. Bulgy.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Mɐʇʇ
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Re: Gearbox TCU

Post by Mɐʇʇ » Mon Jan 29, 2024 8:36 am

That’s what she said
"not a professional engineer, mechanic and mechanist"

Sxcarmyboi
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Re: Gearbox TCU

Post by Sxcarmyboi » Tue Jan 30, 2024 10:03 am

Iv got perfectly good working TCU available if needed
C5 RS6 Avant
800+ BHP loading
1100+ ft lb loading

bam_bam
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Re: Gearbox TCU

Post by bam_bam » Thu Feb 01, 2024 9:16 pm

Shoppinit wrote:
Sun Jan 28, 2024 8:04 pm
Mmm. Bulgy.
lolsie.
No matter where you go, there you are.

Frazz82
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Re: Gearbox TCU

Post by Frazz82 » Thu Feb 22, 2024 6:07 pm

Took a punt on a second hand TCU which arrived today, fitted it an no more fault codes so fingers crossed its fixed.

Feel like it's drives better aswell but nor sure if it's just in my head.

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