BMW M5 Wartungshandbuch PDF herunterladen (Seite 89)

21

9

Service information

Sequential M gearbox SMG 3

Initialization

As on the SMG 2, the SMG control unit must

newly adapt and store various parameters

after a component has been replaced in the

area of the clutch or gearbox as well as after

programming.

Clutch teach-in function

This function is used to adapt the clutch to the

characteristics stored in the control unit. The

clutch grab point is taught-in with the engine

running.

The clutch is released and, after the input

shaft has stopped, initially, the clutch moves

quickly close to the grab point and then slowly

approaches the grab point.

This procedure is terminated if a transmission

input speed is already measured during the

fast approach phase as there is obviously a

fault in the system (e.g. bleeding).

If a valid value is measured during the slow

approach of the clutch towards the grab point

this value is stored in the SMG control unit.

Adaptations

It is necessary to check the gearbox

mechanism after replacing a gearbox,

components of a gearbox or the SMG control

unit. The following adaptations are provided in

the GT1/DISplus.

The most important adaptations in the

gearbox are:

• Shift range mid-points

• Valve characteristics

• Transmission characteristics

• Longitudinal acceleration sensor offset.

Shift range mid-points

This function ensures a gear can be

disengaged without previous adaptation of

the transmission characteristics.

Valve characteristics

The shift range valves in the hydraulic system

are designed as proportional valves. Due to

the tolerance scatter in series production, it is

necessary to teach in the offset current of

these valves.

The current at which the corresponding

selector rod begins to move is determined.

This value is stored as the offset current in the

SMG control unit.

The current consumption of the proportional

valves is determined in both switching

directions.

Transmission characteristics

In this adaptation phase, the selector rods are

moved to the end positions and the actual

values determined.

The measured values indicate whether a gear

is engaged.

The selector rod for reverse gear is

additionally monitored by a redundant sensor

whose values are also stored.

In addition, the hydraulic pressure is read off at

this selector rod and the selector rod is

monitored to ensure it remains in the end

position.

Longitudinal acceleration sensor

The measured value of the longitudinal

acceleration sensor has a constant offset. This

value is determined when the vehicle is at rest

in horizontal position and therefore the

longitudinal acceleration is zero.

The actual values are permanently sampled.

As soon as a sample value deviates by more

than a reference value, external influences are

assumed and the adaptation procedure is

terminated to ensure no falsified acceleration

values are measured during vehicle operation.

1 2 ... 84 85 86 87 88 89 90 91 92 93 94 ... 119 120

Kommentare zu diesen Handbüchern

Keine Kommentare