Electrically adjustable steering column (ESC), function

P46.15-2507-76

A1 Instrument cluster

A85 Left door lock

M20/1 Steering column in/out adjustment motor

M20/2 Steering column up/down adjustment motor

N2/10 Supplemental restraint system control unit

N10/1 Front SAM control unit with fuse and relay module

N32/1 Driver seat control unit

N69/1 Left door control unit

N73 Electronic ignition switch control unit

N80 Steering column module control unit

N135 Steering wheel electronics

S22 Left seat adjustment switch group

S59 Steering column adjustment switch

S110 Left multifunction steering wheel button group

S111 Right multifunction steering wheel button group

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CAN B Interior CAN

CAN E Chassis CAN

LIN B5 Left door LIN

LIN E1 Steering LIN

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Function requirements, general

 Steering column normalized

Electrically adjustable steering column (ESC), general

The adjust/store steering column function allows the steering column to be adjusted to various different positions and these positions to be stored.

The easy entry/exit function makes it possible for the driver to get in and out of the vehicle easily. In the process the steering column is moved upwards before getting in or out. The steering column is adjusted and the current position of the steering column is stored by the driver seat control unit by actuating the steering column up/down adjustment motor.

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 Normalization of the steering column is important for the limitation of the adjustment range.

For normalization of the steering column the respective limit stops of the steering column adjustment are approached and the counter reading of the Hall sensor signals is stored as the normalizing position.

The electrically adjustable steering column includes the following subfunctions:

 Function sequence for adjust/store steering column

 Function sequence for steering column adjustment easy entry and exit feature

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Function sequence for adjust/store steering column

The adjust/store steering column function allows the steering column to be adjusted to various different positions and these positions to be stored.

The adjust/save steering column function sequence includes the following subfunctions:

 Function sequence for adjust steering column

 Function sequence for save position of steering column

 Function sequence for call up saved steering column position

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Function sequence for adjust steering column

Actuation of the steering column adjustment switch is read in by the steering column tube module control unit.

The signal is sent over the chassis CAN to the front SAM control unit, which routes the signal to the interior CAN.

The driver seat control unit picks up the signal and depending on the request it actuates the steering column in/out adjustment motor or the steering column up/down adjustment motor. This actuation takes place as long as the signal is set or until an end position is reached.

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Function sequence for save position of steering column

The current position of the steering column can be saved together with the position of the driver seat and the outside mirror.

The position of the steering column is defined by the Hall sensors integrated in the steering column adjustment motors.

Saving is done using the following switches in the left front seat adjustment switch group:

- Left memory function switch

- Left memory switch 1

- Left memory switch 2

- Left memory switch 3

Operation of the left switch group, seat adjustment is read in over the left door LIN by the left door control unit and forwarded over the interior CAN to the driver seat control unit. This uses the Hall sensor signals from the steering column adjustment motor to store the current position of the steering column adjustment motors.

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 The instrument cluster emits an acknowledgment tone when the position is saved.

The corresponding positions are saved in the driver seat control unit. Up to 3 different data records can be stored.

There are two ways of saving positions:

- Press and hold down the left memory function switch, then press the corresponding left memory switch

- Press the left memory function switch for t > 100 ms and then release, then press the corresponding left memory switch within t  0.2 s to t 3 s

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Function sequence for call up saved steering column position

The following operating modes are available to move to a stored position:

"Hold memory":

Press and hold left memory 1 switch, left memory 2 switch or left memory 3 switch until the stored end position is reached. Releasing leads to immediate termination of the adjustment procedure.

"Press memory":

Press left memory 1 switch, left memory 2 switch or left memory 3 switch. The stored end position is moved to after the corresponding switch is released.

Operation is read in over the left door LIN by the left door control unit and forwarded over the interior CAN to the driver seat control unit. This then actuates the steering column adjustment motors.

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Additional function requirements for steering column adjustment easy entry and exit feature

 The easy entry and exit feature is activated through the instrument cluster

 Drive position stored

Function sequence for steering column adjustment easy entry and exit feature

The easy entry/exit function makes it possible for the driver to get in and out of the vehicle easily. In the process the steering column is moved upwards before getting in or out.

The easy entry/exit function can be activated or deactivated in the instrument cluster via the "Settings" menu in the "Comfort" submenu. The corresponding selection is made using the multi function steering wheel button groups.

The signals of the multifunction steering wheel button groups are read in by the steering wheel electronics and sent over the steering LIN to the steering column tube module control unit. The steering column tube module control unit routes the signals over the chassis CAN to the instrument cluster.

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The instrument cluster sends the status of the easy entry/exit function to the driver seat control unit over the interior CAN.

The steering column adjustment easy entry and exit feature includes the following subfunctions:

 Function sequence for move to easy entry/exit position

 Function sequence for move to drive position

 Function sequence for repeat limiter

 Function sequence for crash-active easy entry and exit feature

Additional function requirements, approach easy entry/exit position

 Intentionally leaving the vehicle by removing the transmitter key (A8/1) from the electronic ignition lock control unit

 Driver door opened

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Function sequence for move to easy entry/exit position

Before the steering column is moved to the exit position, the driver seat control unit stores the current position of the

steering column (driving position) so that the steering column can be moved back to its initial position again after the adjustment process.

The circuit 15 status is sent by the electronic ignition lock control unit to the interior CAN.

The status of the driver door, as defined by the status of the left front door rotary tumbler switch (A85s1), is sent to the interior CAN by the left front door control unit.

The driver seat control unit reads in all relevant information and actuates the steering column up/down adjustment motor accordingly.

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Function sequence for move to drive position

After the driver has got into the vehicle, the steering column is moved back to the drive position.

The driver seat control unit actuates the steering column up/down adjustment motor under the following conditions in order to return the steering column to the drive position:

- Closing driver door with circuit 15 On

- Change from circuit 30 to circuit 15C with driver door closed

- Change from circuit 15C to circuit 15R with driver door closed

- Change from circuit 15R to circuit 15 ON with driver door closed

The circuit 15 status is sent by the electronic ignition lock control unit to the interior CAN.

The status of the driver door is placed on the interior CAN by the left door control unit.

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The driver seat control unit reads in all relevant information and actuates the steering column up/down adjustment motor accordingly.

Function sequence for repeat limiter

The repeated insertion and removal of the transmitter key in and out of the electronic ignition lock control unit causes a switchover between the "move to entry/exit position" function and the "move to drive position" function. To prevent overloading of the steering column up/down adjustment motor, the number of requests is limited to five adjustment cycles.

The number of adjustment cycles is reset as soon as the electronic ignition lock control unit sends the status of circuit 15R or when the left door control unit signals the "driver door open" or "driver door closed" status.

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 The functions approach entry/exit position or approach driving position are aborted under the following conditions:

- Undervoltage or overvoltage

- Manual adjustment request over the steering column adjustment switch

- Memory adjustment request

- Reversal of circuit 15 transition or driver door status change

- Defect at a Hall sensor integrated in the steering column up/down adjustment motor

Function sequence for crash-active easy entry and exit feature

Following the occurrence of a crash event the driver seat and the steering column are automatically moved upwards to a defined position.

The crash signal is sent by the supplemental restraint system control unit over the chassis CAN to the front SAM control unit and forwarded from there over the interior CAN to the driver seat control unit.

The driver seat control unit then actuates the steering column adjustment up/down motor.