Firstly I would stick a decent earth lead from battery to gearbox or engine to rule out an issue with earths.

 

One scenario is a problem with the TCT module/connector which then draws a much larger current causing the lights to dim. Does it happen only when the roads are wet? Also make sure the new battery has the correct voltages for engine off and engine on and the alternator is charging correctly, given there was a historic error code.

 

I am keeping an eye on this topic, since I am experiencing the same kind of issue in my Mito 1.4 Multiair 135 TCT. I would also describe it, next to slow shifting, as a feeling of clutch slip, revs rise and there's very little acceleration going on. Thus far I replaced the clutches, DMF, hydraulic accumulator, transmission fluids and battery (AGM). Next to that I put in two new earth straps, to rule out this potential cause. For some reason, the problem of clunky and slow shifts still exists. On two occasions, I had an error code, related to clutch wear and one (U code) for CAN BUS. In my case the gearbox shifts perfectly fine after resetting adaptive parameters, however after some days it will go back to it's old clunky nature. At the moment, me and my mechanic reached a point of confusion.

 

Yeah its weird initially after resetting adaptive parameters yours work fine but later going back performing shitty. Is it possible the chip or whatever controls the adjustment is faulty x% of the time giving the same errors?

I thought about TCT adjusting badly for our driving style? To be honest I need to spend more time understanding TCT but AFAIK at the moment it somehow adjust (lol). At the moment I cant comprehend why its good, how the car knows how I want to drive and not sure how it 'learns' and how each program of DNA adjust to it as well. Im probably dum but it partly seems ******** to me... But after changing gear oil, updating drivers both of ECU and TCT even putting on different softwares from reputable tuners I literally changed my driving star thinking "I am an old lady,should drive like that" and it gives me same slow falling down of RPM meter after shifting. Now thinking as writing this, the error comes out even when I use it in 'manual' mode with the straps on the steering wheel. So I doubt it causes by faulty adjustments of TCT- but I am just guessing.

So maybe its some hidden error of one of the circuits? Its weird my headlights and every light of the car is blinking when shifting gears.

I am curious what is your oppinion about this wall of text, @Mito_BronzoNL

 

Thank you @Mito_BronzoNL

I called a guy who is referred in my country's forums one of the best, he said its most likely some hidden electronic error that may be pretty hard to find and might need to blow some of the parts of the car to pieces to see whats up.

In about 2-3 weeks he will service my car will let you know how it goes.


I assume your extra earht strap is the stripped copper cable? Isnt it dangerous to leave like that?

 

You said you updated the engine ecu and tct ecu software but does that include resetting the adaptive parameters ? I can see 7 different options in MES to do with calibration and resetting parameters, some normally after part replacements. I'm not saying it is recommended to try them as I have a manual but have you tried any of them ?

 

Yeah one of the mechanics reset adaptive parameters as well. I doubt the problem is software related because on 3 different programs it does the same thing. What is weird also with mine I don't see much difference in Natural mode and Dynamic mode as far as 0-100 km/h goes because dynamic mode revs up the engine so much without producing much force on the road. Keep in mind weird shifting still exists on every mode of DNA.

 

Not a problem I have, but did this ever get resolved? To me, the dimming lights suggest either poor battery connections, or earth, and a resistance spike dropping volts.... or something in the TCT electronics taking excess current... and dropping volts. Either might be behind the observed symptoms.

 

Sorry its a bit late.

Yes we found it as the problem got worse. One of the battery's connection is the culprit, not sure how to describe which I can send pictures if anyone want. I got generator refurbished and new battery in 2022 March. Car was better for a while than started having those symptoms again slowly. In last couple of weeks car started to show transmission fault (not registered by the ECU , good OBD scanner for Alfas Didnt see anything afterwards), started blinking lights more often and then seemed like battery died. Today we tested it and IT IS the reason for faults it looks like. Its strange how it affects TCT behaviour too. Good thing it got worse and now we know it 100% that its not some hidden very costly repair.

Everything else on the car is top shape, was tested on dyno and so on.