Auto problem

[watercool]

Hi everyone,

I have a 2006 Yaris with auto transmission. I've had a problem with the gear selection which has got worse and worse.

The car is very jerky to drive, when I press the accelerator the car pauses and then decides to engage and move forward. This pause has got longer over a year. It's now at the point where it's a bit dangerous ie pulling out at junctions.

Because of the unreliable/unpredictable nature of the gear selection it's quite a jerky ride when in the lower gears as it surges forward once selecting.

I really don't know where to start with it, never had an auto before.

[dj92]

I'd recommend to buy a Toyota-specific scan tool ("MINI-VCI"), which can be had for 20...50$ in china.

[WeeYari]

How many KMs on the vehicle?

Have you checked the transmission fluid level?

Has transmission fluid ever been changed?

[IllusionX]

You don't have to "select" gears while driving auto.. you put it in "D", and drive away.. and normally just leave it there until you need to park or go in reverse.

[watercool]

I mean the car 'selects'/puts the car in to a gear, not me.

It's done about 60,000 miles (96,000km?) and never had the trans fluid changed.

[marcus]

I mean the car 'selects'/puts the car in to a gear, not me.

It's done about 60,000 miles (96,000km?) and never had the trans fluid changed.

now thats automatic.. really you dont have to shift the gear from P to D?

[CTScott]

I am confused as to which transmission you have. The EPC does not show any automatics being paired with the 1.3L engine for either French or Japanese made 2006 Yaris.

[CTScott]

Ah, I see it now. You have the C551A MMT (multi mode transmission):

"The multi-mode manual transmission has been developed from the conventional
manual transmission by adding actuators that are directly controlled by electric
motors. The transmission control system consists of an electronic throttle control
system, clutch actuator, shift and select actuator, sensors, a shift lever, and a
transmission control ECU. The system offers automatic clutch operation and two
driving modes: automatic shifting E mode and manual shifting M mode"

[CTScott]

You can grab the service manual for your transmission from the Micro Image forum:

http://www.microimageonline.com/downloads/C53A-C551A/C551A%20MULTI-MODE%20MANUAL%20TRANSAXLE.pdf

There is a calibration procedure that may help (and that can be done without the Toyota Intelligent Tester).

Page 74 shows your current issue and all of these as potential causes:

1. Transmission unit (Gears, bearings,
shift fork, synchronizer ring, shift key,
etc.)
2. Clutch disc (Clutch cover)
3. Clutch stroke sensor
4. Clutch actuator assembly
5. Shift stroke sensor
6. Select stroke sensor
7. Shift and select actuator
8. Shift lever position sensor
9. Shift lock solenoid circuit
10. Shift lever assembly
11. Speed signal circuit
12. Transmission control ECU

[watercool]

Sorry folks, yeah it has the auto bit (Where I can put in R, E or N) then you can slide the gear stick to the right and there is a plus and minus sign to change gear yourself.

The exact model is a T-Spirit and yes it is MMT (always wondered what that stood for!)

Thanks for all that info, so it could be a number of things, great haha bloody cars!

[CTScott]

Sorry folks, yeah it has the auto bit (Where I can put in R, E or N) then you can slide the gear stick to the right and there is a plus and minus sign to change gear yourself.

The exact model is a T-Spirit and yes it is MMT (always wondered what that stood for!)

Thanks for all that info, so it could be a number of things, great haha bloody cars!


I never really looked into how exactly the MMT worked before. It takes a nice simple manual transmission (the C51 that is is based on) and makes it about as complicated as can be.

[watercool]

Sounds very much like that haha

I didn't think you'd have Yaris' over in the US, bit small for you guys aren't they?!

[CTScott]

Sounds very much like that haha

I didn't think you'd have Yaris' over in the US, bit small for you guys aren't they?!

There are actually many of us with them here, but we are definitely a minority. This morning at Starbucks I was parked between a Hummer H1 and 3 mile long Ford Expedition.

[dj92]

I've read the MMT would have a quite dumb algorithm.
One of the reasons I like manual transmission best.
(and dual-clutch-transmission is bad, too: I often jump a gear)

[IllusionX]

Sorry folks, yeah it has the auto bit (Where I can put in R, E or N) then you can slide the gear stick to the right and there is a plus and minus sign to change gear yourself.

The exact model is a T-Spirit and yes it is MMT (always wondered what that stood for!)

Thanks for all that info, so it could be a number of things, great haha bloody cars!

ahh.. MMT transmission.. i drove one of these on a Sart ForTwo. I hated the "auto" mode, as it's really jerky and shifts at the weirdest moment. But you are right about the delay.. even though i never drove a toyota one, to get started from a stand still, it's quite jerky and takes some time before get car gets moving.

Yours may or may not have a problem, but after i got used to the smart, it's quite a blast to drive the MMT.