Toyota
Ford Kuga
 Service Manual
Automatic Transmission/Transaxle » Transmission Description (System Operation and Component Description)
Gearshift control

Adaptation

The TCM monitors every shift operation in all driving conditions to make even and smooth gear shifts possible. This is done by the control module, which either lowers or increases the hydraulic line pressure during gearshifts.

The changed pressure values are stored in the control module memory after the engine is switched off and retrieved during engine starting. This improves the shift comfort and extends the service life.

Full adaptability occurs when the following criteria are met:

  • Throttle plate opening is constant.
  • Transmission fluid temperature between 65 C and 110 C.

Shifting from 'P' to another transmission range

To be able to move the selector lever from 'P' into another transmission range, the ignition must be switched on and the brake pedal pressed (stoplamp switch on). The TCM detects the position of the brake pedal via the CAN data bus and the engaged transmission range from the TR sensor.

Based on this information, the TCM transmits a signal to the select-shift switch module. This activates the brake shift interlock actuator in the selector lever assembly.

When the brake shift interlock actuator is activated, the locking pin is retracted so that another transmission range can be selected.

The brake shift interlock actuator is deactivated when the ignition is switched off. It is mechanically locked when the gear selector lever is in 'P'.

Automatic transmission, selector lever in position "D"

The TCM adapts the shift points to match the driving conditions. Normally the TCM is in adaptive mode and gear changes take place adapted to the driving conditions. If special driving conditions are detected, the TCM switches to predefined characteristics.

When driving with normal acceleration, the TCM uses a preset shift program which is optimized for economical driving.

This shift program is suitable for "normal" driving and delivers early upward changes and torque converter lockup. Furthermore, the transmission fluid pressure is adapted to make smooth engagement of the gears possible.

Sport mode, selector lever in position "S"

The transmission switches from automatic operation into sport mode. In this mode the TCM switches to another set of characteristic curves.

These characteristic curves for control of the gear changes are adapted to sporting calculations (e.g.

gear change at higher engine speed).

In the sport mode shift program the shift points are set so that good performance is offered. Changing down occurs at lower engine speeds.

Manual gear changes (select-shift mode) can be made in sport mode by moving the selector lever in the (+) or (-) direction.

Changing gear in select-shift mode

If you move the selector lever to 'S', the automatic transaxle remains hydraulically in 'D' position. If you move the gear selector lever forwards (-), the select-shift switch module transmits a downshift signal to the TCM.

If you move the gear selector lever backwards (+), an upshift signal is transmitted to the TCM. In the instrument cluster, the symbol when the selector lever is in the 'S' position changes from 'D' to the current gear, for example 3.

The TCM transmits a signal to the select-shift switch module to switch on the light emitting diode for 'S' and to switch off all other light emitting diodes. The TCM decides whether the shift process is possible.

If the shift process is permitted, then the various valves are activated according to the intended combination for each gear.

In certain situations however, the TCM determines the gear shifting. The following applies:

  • If the vehicle is stationary, only 1st, 2nd and 3rd gears can be selected. 4th gear can be selected at speeds over 30 km/h and 5th gear at speeds over 40 km/h.
  • The kickdown function is only available in the automatic transmission range 'D'
  • Automatic gear changes into the next higher or next lower gear occur at fixed vehicle speeds and fixed engine speeds
  • The permitted engine speed for manual change down agree with that for the kickdown change up, i.e. an engine speed of approximately 6000 rpm.
  • If the temperature inside the transmission rises too high, the TCM takes control of the shift decisions in order to select a gear in which activation of torque converter lockup at the current speed is possible
  • Torque converter lockup is possible in 3rd, 4th and 5th gear. (1st and 2nd gears do not have torque converter lockup)

The signal that specifies the position of the lever to the select-shift switch module is generated as follows in the selector lever position 'S': there is a Hall sensor at the printed circuit board for the module for each of the three selector lever positions. A permanent magnet on the cover in the selector lever affects the output signals to the control module from the sensors. The control module recognizes the position of the lever by the differences in the signal properties.

Selector lever from 'N' to 'R' position

The TCM only permits shifting to reverse gear if the vehicle speed is less than 4.35 mph.

If the vehicle speed is greater than 7 km/h (approx.

4.35 mph), the clutch (C2) and the multi-plate brake (B3) are not activated and the gearshift is thus prevented.

Self-test and Diagnosis

The TCM monitors all the transaxle sensors and electronic components including the PCM. If a fault occurs, the driver is informed via a warning indicator and a text message in the instrument cluster. Faults are stored as DTCs in the fault memory of the TCM and can be read out and cleared using the IDS.

Temperature controlled torque converter lockup

If heavy load and high ambient temperatures cause an abnormal rise in the transmission temperature, torque converter lockup is activated as often as possible (temperature controlled lockup).

This reduces the slip and the heat developed in the transmission. When the temperature drops below +20 C, torque converter lockup is not used.

Slip locking

When changing gear this function makes it possible for the gears to engage more smoothly with reduced vibration and less noise. In this mode, the torque converter clutch is activated but not fully locked.

The following conditions must be met for the function to activate:

  • Gear selector lever in position D or S.
  • Gear 3, 4 or 5.
  • The transmission input speed is 1100 rpm or more and the throttle plate opening 20 - 35%.
  • The transmission fluid temperature is 40 - 120 C.

Hill climbing

The TCM can change the shift pattern slightly when driving uphill to avoid changing gear too often.

The TCM detects uphill driving by comparing the engine load transmitted by the PCM with the engine speed. If the engine load increases and the engine speed falls, then the TCM causes the transaxle to shift to a lower transmission range in order to increase the traction force.

Downhill driving

The TCM detects downhill driving by comparing the engine load and engine speed values transmitted by the PCM with the OSS sensor signal. In order to prevent overloading of the vehicle brakes, the TCM causes the transaxle to shift to a lower transmission range.

Hill-hold function

If the vehicle is stopped on an uphill incline, the TCM detects this through the faster drop in engine speed compared with the drop in engine speed when stopping on the flat. In this situation, the hydraulics are actuated by the TCM in such a way that the vehicle is prevented from rolling back. This function is not used on steep inclines.

If the vehicle is parked on an uphill incline (ignition switched off), the hill-hold function is not active when pulling away.

Altitude correction

Lower air density results in reduced engine performance. In order to compensate for this operating situation, the TCM changes the shift points.

Selector lever lock

To prevent the selector lever being accidentally moved from the P or N position, the vehicle also has an electrically operated selector lever lock.

This blocks the locking pin in the locking segment and thus locks the selector lever in the P or N position.

Shifting from P into another transmission range

To be able to move the selector lever from P into another transmission range, the ignition must be switched on and the brake pedal must be depressed (stop light switch on). The TCM detects the position of the brake pedal via the CAN data bus and the engaged transmission range from the TR sensor.

The signal is then transferred from the TCM to the select-shift switch module in order to activate the solenoid valve in the selector mechanism assembly.

In position P, the solenoid valve is activated and the locking pin is pulled in so that the lock button on the selector lever can be pressed as usual to engage another transmission range.

In the selector mechanism assembly there is a Hall sensor which is affected by a permanent magnet on the gate of the selector mechanism assembly.

If the selector lever is moved from the P position, both the Hall sensor and the selector lever lock solenoid are simultaneously deactivated, to prevent the selector from being kept in the N position.

If the ignition is set to "I" or "0" the solenoid valve is deactivated. When the selector lever is in the P position, it is mechanically locked because it has no voltage.

Shifting from N into another transmission range

The conditions are the same as for shifting from P into another transmission range.

However, the lock button on the selector lever must be pressed to be able to select R or P.

    More about «Transmission Description (System Operation and Component Description)»:

    System Operation

    Gearshift control

    Power flow through the transmission

    Service instructions

    Component Description

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