Citroen C5 Aircross Quiz
Automatic gearbox control

Operating principle

In this manual: Automatic gearbox control
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DIAGRAM OF THE AUTOMATIC SEQUENTIAL-CONTROL GEAR SELECTOR GATE

Schema de la grille de levier de boite automatique a commande sequentielle
Diagram of the automatic sequential-control gear selector gate

By moving the lever, the driver selects an operating mode for the automatic sequential-control gearbox.

Par un appui sur les touches, il va sélectionner un programme, neige ou

By pressing the buttons, the driver selects a programme: snow or sport.

ELECTRICAL DIAGRAM OF THE AUTOMATIC SEQUENTIAL-CONTROL GEAR SELECTOR

Schematisation electrique du levier de selection boite automatique a commande sequentielle
Electrical diagram of the automatic sequential-control gear selector

The electrical states of positions P, R, N and D are read from the multifunction switch on the automatic sequential-control gearbox.

The electrical states of the sequential control are connected directly to the control module.

The table shows the electrical states on wiring S5 and S6 of the sequential control according to operating mode.

NOUVEAUTES SUR LA BOITE DE VITESSES 4HP20

NEW FEATURES OF THE 4HP20 GEARBOX

32 shift strategies, compared with 10 previously.

Additional self-adaptive strategies.

Strategies for uphill and downhill driving.

Strategy for urban driving.

Emissions strategies.

Manual shift strategy.

Snow strategy for uphill and downhill driving (automatic engagement when grip is lost in D).

Strategies for cruise control.

Shift lock (gear selector locked in P).

Key lock (must be in P before removing the ignition key).

Drag reduction (prevents the vehicle creeping forward at idle).

Cornering recognition (maintains the engaged gear).

NEW FEATURES OF THE AL4 GEARBOX

Additional shift strategy for impulse manual control.

IMPULSE MANUAL CONTROL

Selecting manual mode

Manual mode is selected by moving the automatic gearbox selector to position M. Impulse manual control can be entered at any time.

  • On entering impulse manual control, the engaged gear is the gear that was engaged in automatic mode.
  • AL4: on entering impulse manual control, if the "snow" programme was selected, the standstill gear in impulse manual control will be the same as the standstill gear in the "snow" programme. A manual impulse still allows the automatic gearbox to be downshifted to a lower gear at any time. A new gear can be stored as the new standstill gear. The new gear must be lower than the previous standstill gear and must be engaged while the vehicle is stationary.
  • 4HP20: on entering impulse manual control, the standstill gear is always 1st gear.

Changing gear in impulse manual control

Gear changes are made by a pulse of the gear selector. A pulse down downshifts; a pulse up upshifts.

  • The "snow" and "sport" programmes are deactivated in manual mode.
  • The self-adaptive shift strategies are deactivated.
  • Kickdown is retained.

Note: Positions P, R, N and D do not exist in impulse manual control mode.

Shift conditions depend on the gear selected by the user being engaged.

  • The vehicle must not be cornering.
  • A selected gear is not engaged if a gear change is in progress.
  • A selected gear is not engaged if it is not within the permitted range of the shift schedule table.
  • The ESP must not prevent gear changes. The ESP may prevent a gear change in critical vehicle handling situations.

Shift schedule priorities

Definition: a shift schedule is a curve that defines the point at which the gear ratio must change. This curve depends on the accelerator pedal position and the vehicle speed.

Depending on the operating modes selected by the driver, the shift schedules selected by the computer are not necessarily applied. Some schedules take priority.

Example: in manual sequential mode, if the computer selects the "low temperature adaptation" shift schedule, this schedule will be applied instead of the "manual sequential control" schedule.

Priorités pour les lois de passage

Upshift conditions

Even in manual sequential mode, the selected gear is only engaged if the operating point is within the permitted range of the shift schedule.

Example: 1st gear of the automatic gearbox is engaged, the driver wants to shift to 2nd gear.

Conditions de montée de rapport
La position de la pédale d'accélérateur ne varie pas. La vitesse a

The accelerator pedal position does not change. Speed has increased. The driver selects 2nd gear. 2nd gear does not engage because it is in zone A. The shift request is stored. Speed continues to increase.

Le 2ème rapport s'engage à l'instant où il intercepte la courbe M12

2nd gear engages when it intercepts curve M12.

Downshift conditions

The same conditions apply when downshifting. The gear can only engage when it intercepts the curve.

Conditions de descente de rapport
Changement automatique de rapport en mode manuel

Automatic gear change in manual mode

To protect the engine and gearbox, an automatic gear change in manual sequential mode has nevertheless been provided.

Changement automatique de rapport en mode manuel
Lors d'une variation de la vitesse du véhicule ou de la position de la

When the vehicle speed or the accelerator pedal position changes, the automatic gearbox changes gear automatically.

This change occurs when the operating point crosses the curves delimiting the permitted zones. This protects the vehicle from engine lugging and over-revving.

Note: 2nd gear may nevertheless be engaged in zone A if the snow program was selected by the driver when entering manual sequential mode.

RETURN TO "DRIVE" MODE

When switching from manual sequential mode back to "drive" mode, the selected shift schedule is the economy schedule, or the schedule that was selected when switching from "drive" to manual sequential mode.

LOCK-UP SCHEDULE

Depending on the operating modes selected by the driver, the lock-up schedules selected by the computer are not necessarily applied.

Some schedules take priority.

Suspension

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