5-speed MMT

C55#A, C251A, C5#A - created on a basis of the corresponding manual gearboxes, supplemented with select and shift actauators, clutch actuator, as well as speed sensor and PNP sensor.

C53A transmission. 1 - clutch actuator, 2 - transmission rotation sensor, 3 - neutral start switch, 4 - back-up light switch, 5 - shift and select actuator

C553A transmission. 1 - shift and select actuator, 2 - clutch actuator, 3 - shift stroke sensor, 4 - select stroke sensor, 5 - neutral start switch, 6 - transmission rotation sensor, 7 - back-up light switch

Shift&select actuator (C53A). 1 - shift motor, 2 - select motor, 3 - shift stroke sensor, 4 - select stroke sensor, 5 - shift pinion gear, 6 - ring gear, 7 - rotation lever, 8 - shift and select lever shaft, 9 - inner lever, 10 - select pinion gear.

Shift&select actuator (C53A). 1 - shift and select actuator, 2 - shift stroke sensor, 3 - select stroke sensor, 4 - shift motor, 5 - select motor, 6 - rotation lever, 7 - select motor shaft, 8 - shift and select lever shaft, 9 - shift and select lever, 10 - ring gear, 11 - shift fork shaft lever. b - select, c - shift

The shift motor via reduction gear rotates and the select motor via gear-rack pair slides the shift and select lever shaft, then the movement is transmitted to the shift fork shaft. The actuator positions are monitored by two Hall-effect stroke sensors.

Shift&select actuator (C53A) /operation/. 1 - ring gear, 2 - rotation lever, 3 - shift and select lever shaft, 4 - inner shaft.

Shift actuator (C553A) /operation/. 1 - shift motor, 2 - shift motor shaft (gear), 3 - ring gear, 4 - rotation lever, 5 - shift and select lever shaft, 6 - shift and select lever

Select actuator (C553A) /operation/. 1 - select motor, 2 - select motor shaft, 3 - shift and select lever shaft, 4 - shift and select lever

The clutch motor via the worm gear and the fulcrum moves the rod and the clutch release lever. The auxiliary spring provides additional force to move the rod, reducing the load on the actuator when the clutch is disengaged. The position of the actuator is monitored by a Hall-effect stroke sensor.

Clutch actuator (C53A). 1 - clutch release lever, 2 - clutch stroke sensor, 3 - clutch motor, 4 - clutch actuator, 5 - worm shaft, 6 - assist spring, 7 - worm wheel, 8 - fulcrum, 9 - sensor arm, 10 - pull rod

Clutch actuator (C553A). 1 - clutch release lever, 2 - clutch motor, 3 - clutch actuator, 4 - clutch stroke sensor, 5 - push rod, 6 - sensor arm, 7 - worm shaft, 8 - assist spring, 9 - worm wheel. a - release, b - engage, c - fulcrum

The clutch cover is equipped with a load controled (LCC) mechanism. If the control unit detects a load increase in the clutch drive as a result of the wear of the clutch disc (measuring current of the actuator motor), then the special mode (with increased clutch stroke) is activated and the LCC mechanism shifts to the next position, changing the height of the pressure plate.

LCC (C53A). 1 - LCC mechanism, 2 - diaphragm spring, 3 - lower pressure plate, 4 - upper pressure plate, 5 - adjustment wedge, 6 - lower rack, 7 - pinion, 8 - spring

MMT uses a shift-by-wire principle - the selector is not mechanically connected to the gearbox, and its position is monitored by a multi-position contact position sensor. MMT operation modes are: E (normal), Es ("sport"), M (manual shifting). In manual mode, the driver can use the shift paddles under the steering wheel.

Selector (C553A). 1 - shift lock control unit, 2 - shift lever position sensor, 3 - shift lock solenoid, 4 - transmission shift main switch

Selector position sensor (C53A). 1 - link 1, 2 - link 2, 3 - contact point plate, 4 - contact point

6-speed MMT

Later robots EC6#A differed from the 5-MMT in the kinematics of the select and shift actuators, presence of a hydraulic clutch drive and absence of LLC.

EC60A transmission. 1 - transmission rotation sensor, 2 - clutch actuator, 3 - park/neutral position switch, 4 - shift and select actuator

Shift@select actuator (EC60A). 1 - shift stroke sensor, 2 - select motor, 3 - shift motor, 4 - select stroke sensor, 5 - shift actuator plate, 6 - select pinion gear, 7 - select actuator plate, 8 - shift and select lever shaft, 9 - shift pinion gear, 10 - ring gear. a - shift and select mechanism

When the select motor is running, rotation is transferred to the pinion gear (A), which moves the plate (B) and than activates the shift and select lever (C).

Select actuator (EC60A) /operation/. 1 - select pinion gear, 2 - select actuator plate, 3 - shift and select lever

When the shift motor is running, rotation is transmitted to the pinion gear (A), then to the driven gear and the gear mounted on it (B). This moves the shift actuator plate (C) and activates the shift and select lever (D).

Shift actuator (EC60A) /operation/. 1 - shift actuator plate, 2 - shift and select lever, 3 - shift pinion gear, 4 - ring gear

As a result, the shift fork shaft lever moves and gears are changing.

When the clutch motor is runnung, the torque is converted by a worm gear, and the rotation is transformed into a movement of the rod. The rod pressurizes the clutch master cylinder allows to engage and disengage the clutch. The auxiliary spring reduces the load on the actuator when the clutch is disengaged, providing additional force on the rod.

Clutch actuator (EC60A). 1 - clutch stroke sensor, 2 - clutch actuator, 3 - clutch master cylinder, 4 - reduction gear, 5 - operating rod, 6 - sensor plate, 7 - assist spring, 8 - worm wheel, 9 - worm shaft, 10 - clutch motor

Toyota MMT system diagnostic trouble codes

Experience

In 2013, corks and champagne were popping in all dealer service workshop of the country: it was three years since the sale of the last model with a robot, and now their problems ceased to be a warranty case, but, on the contrary, turned into a new way to rob clients. Who would have thought that completely new and, frankly, primitive Toyotas, with a low milage can cause so much regularly recurring troubles. Some of them were simply dangerous - for example, shift to neutral gear at the most inopportune moment (like overtaking). Some are unpleasant - the disappearance of the creep mode (usually characterized as a lack hill-start assist and car pulling back), plus the usual for robots jerks and inadequacies. AMT did not like a long traffic jams. Did not like too hot weather in summer and too cold temperatures in winter. And of course, the owner should constantly expect of that inevitable moment when the AMT will refuse to engage gears and completely immobilize the car (at best, the first time it will be cured by the ignition switch off-on). The vast majority of troubles were somehow related with the clutch: wear of the bushings of the actuator worm wheel, overload and burn-off of the actuator motor, wear of the motor brushes, scuffing of the release bearing guide, rapid wear of the clutch disc, overheating, inoperability of the LCC mechanism... Mechanical defects caused a load increase, the motor current exceeded the threshold and the notorious error P0810 was not long in coming. Select/shift actuators were much less capricious, but also not eternal. The selector position sensor suffer aging and oxidative processes. The cherry on top was poor software quality - the final revisions of the control units coding appeared almost in the mid-2010s, after a decade of dubious experiments. During those 7-8 years, while robots were quite relevant, the owners, through their sad experience and private craftsmen, by trial and error, discovered a lot of subtleties in repair and operation. What, unlike time-tested automatic transxles, MMT work in a delicate balance of elements, which is simple to disrupt and difficult to restore. That it is necessary to monitor changes in production, using latest modifications of spare parts for the repair. That, on the one hand, you will have to abandon experiments with a non-OEM parts, and on the other hand, DIY improvements will become the norm. That the PC-DLC3 diagnostic cable should always be in the glove box, and the techstream label can be attached to the notebook taskbar (MMT live data parameters should have been checked at least as often as the engine oil was changed). That the repair may not give any result if it is performed by usual technician but not specially skilled in Toyota MMT master. Finally, some overlooked that works with the MMT transmission should be accompanied by one or another component of the whole complex of initializations and calibrations (Target Clutch Clamp Position Control, Clutch Actuator Preload, Initialization of MMT ECU, Initial Calibration of MMT System, MMT Synchronization Position Calibration). Others (including dealers), on the contrary, performed the initializations and reset of adaptations/settings for any reason, without replacing the corresponding components, which only accelerated the malfunction development and the likelihood of breakage of other elements. Well, practical folk experience found the most radical way to solve the MMT problems - a swap for a traditional hydromechanical automatic transmission, which was available for gasoline models (e.g. U341E) and was cheaper than one high-quality MMT repair. And as usual, before starting work, it is recommended to look through the genuine bulletins on the topic of interest - for MMT, more than enough of them have been released and revised, below are the most recent and relevant ones. • Today, the first document for any problems with MMT - TSB CP-0081T-0815 "MMT diagnosis summary TSB (5,6speed)" (2015) - describes the primary diagnosis algorithm and specifies the direction of the search, with reference to several options for standard faults and TSBs. • TSB CP-0009T-0113 "5MMT P0810 and No creep & Clutch Judder" (2015) replaced a number of bulletins of previous decade (CP-0006T-0112, CP-0021T-0110, CP-0026T-0110, CP-0071T-1208, CP-5013, CP-6003...). The changes affected the software of the control unit, the friction in the clutch release mechanism was reduced, the torque of the clutch motor increased. The document prescribes the installation of a modified MMT control unit (89530-12251 ⇒ 04009-31112)*, clutch kit (31250-19095 ⇒ 04000-03352)*, clutch actuator kit (04008-39112 ⇒ 04000-19112, includes release bearing and fork)*. * - example shows Auris ZRE151 part numbers Some other TSB: CP-0011T-0212 "6MMT DTC P0920" (2012, shiftselect actuator replacement) CP-0018T-0110 "DTC P0905 P0915 on C53A transmissions (MMT)" (2010, engine compartment wiring replacement) CP-0022T-0411 "6MMT DTC P0900 Clutch actuator circuit" (2014, actuator motor circuit short due to contamination of brushes wear particles) CP-0037T-0412 "6MMT Engine does not crank - Neutral start switch" (2012, PNP replacement) CP-0085T-1213 "Aygo 5speed MMT impossible to drive due to release bearing breakage" (2015, clutch kit, fork and release bearing replacement) CP-0116T-1010 "6-MMT malfunction resulting in DTC P0810" (2010, clutch stroke sensor and clutch disk replacement) CP-0149T-1214 "6 speed MMT malfunction resulting in DTC" (2014, clutch stroke sensor, clutch disk and clutch actuator replacement) As a result, we can say that MMTs are confidently included in the top technological failures of Toyota's recent history. And the best solution to their problems is still prevention - it is enough just not to purchase models with such a transmission.

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