Tiago AMT weird gearbox behaviour: Service centre says replace the unit

The transmission causes no problems while the engine / car is running.

BHPian zeal_motorist recently shared this with other enthusiasts.

I drive a Tiago XTA (AMT) 2017, I've been facing an issue with the transmission and somehow it worked fine during summers in NCR. But in the last winter and now again in November, this has been a constant problem. You might already know that AMTs can only be turned on with Neutral gear and brakes applied (most of the cars).

Issue

Even if I leave my car on Neutral before turning it off, the gear sometimes shifts to manual-neutral or even manual-first from Auto-Neutral as I turn the key to the engine off and the car makes a warning sound. The next time I try to switch it on, sometimes it's changed back to Neutral (Auto/Manual - in which case the car can be switched on) other times it just gets stuck in First gear and refuses to switch on.

• The transmission causes no problems while the engine/car is running.
• The gear gets reset to Neutral upon disconnecting and connecting the battery, but even that didn't work once.

Resolution Offered

I took my car to the authorized service center for this issue and they charged us for changing the clutch plate even though the older one was in perfect condition (recently replaced), and refused to pay back the money. No resolution even though they had kept the car for about 10-12 days and tested it, and suggested a complete AMT unit change which would cost more than 80k INR. No help on this from Tata online support as well.

I don't know why the gear type changes to manual on its own and what could be the root cause for this, any help is appreciated.

Here's what BHPian Jeroen had to say about the matter:

I don’t think this would be caused by the clutch or the oil. At least I can’t imagine it would. The clutch has nothing to do with this and problems with too low oil or degraded oil tend to cause problems when driving and or shifting, not this.

There must be something wrong with the gear and or interlocking mechanism on the gear switch assembly. There might be a little play or something along those lines. I would start checking the proper operation of the neutral switch and proceed from there onwards.

I would take it to a different service centre because these guys haven’t got a clue I think.

Here's what BHPian sagarpadaki had to say about the matter:

My thought is that since the gear shift is hydraulically driven by an actuator in an AMT, the old AMT kit oil may be impeding the operation of the hydraulics thus causing shift issues.

Here's what BHPian ObsessedByFIAT had to say about the matter:

I had complained about inconsistent / jerky gear shifts in my Kwid EasyR. The service centre folks mentioned that they recalibrated the gear shifts through an OBD scan. I don't know how true that was, but I haven't faced the same issue in the past more than 8k kms. Maybe worth a try in your case as well?

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