Shift Operation, Function - GF27.60-D-2000HAG

TRANSMISSION 722.9 in MODEL 906

Function requirements for shift operation, general

"Circuit 87 ON"
"Circuit 61 ON"
Engine RPM from CDI control unit (N3/28) (with engine 651) or CDI control unit (N3/30) (with engine 642)
Transmission not in limp-home mode
Signals from the engine compartment-CAN (CAN C)

Shift operation, general

The electric controller unit (Y3/8) converts the electrical signals coming from the control unit (Y3/8n4) into hydraulic signals.

The ESM control unit (N15/5) routes the selector lever positions "P", "R", "N" and "D" taking various pieces of information into consideration over the engine compartment-CAN to the control unit.

The ESM control unit changes the position of the selector range lever which is transmitted mechanically to the selection range sensor (Y3/8s1).

The shift range is displayed in the instrument cluster (A1). The signal flows from the control unit over the engine compartment-CAN to the instrument cluster.

The shift range can be changed in the forward gears while driving, but the control unit prevents a shift at unacceptably high or low engine speeds.

Function sequence for shift operation

The function sequence is described in the following steps:

Function sequence for shifting up and down
Function sequence for shift operation, gear 1 to 2

Function sequence for shifting up and down

The driver can select the following functions by operating the selector lever (touch mode (+/-)):

One press towards "-" activates the gear limitation or touchshift function (if the engine RPM permits, a downshift is made to the gear that lies on gear below the currently used one). Pressing and holding towards "-" selects the "Shift to optimum gear" function (the gear which permits the best-possible vehicle acceleration is then selected).

One press toward "+" with the gear limitation function selected increases gearshift limitation by one gear (e.g. from 3 to 4).

One press toward "+" in gear range "D" sends an upshift request to the transmission (the transmission shifts up if the driving situation allows).

Pressing and holding toward "+" cancels the gear limitation function completely (gearshift to "D").

The reverse gear, park position and the neutral position are shifted to directly using the selector lever (upshift/downshift).

Function sequence for shift operation, gear 1 to 2

Multidisk brake B2, multidisk brake B3 and multidisk clutch K3 are engaged in 1st gear. When shifting from 1st gear to 2nd gear, multidisk brake B3 is disengaged and multidisk brake B1 is engaged. The shift is initiated by the control unit. Here, the multidisk brake B1 is filled and the pressure in multidisk brake B1 is increased continuously. Simultaneously the pressure in multidisk brake B3 is reduced.

This involves a flowing transition. When the 2nd gear torque is reached, the engine speed must be adapted to the 2nd gear level (elevation phase).

This speed adjustment is achieved by the pressure in the multi-disk brake B1 being increased and, if necessary, engine torque being reduced via the CDI control unit.

A forced downshift occurs at excessively low RPM and a forced upshift occurs at an excessively high RPM. When the vehicle is stationary the transmission automatically shifts into 1st gear. It is possible to start off both in 1st or 2nd gear.

Limp-home mode, function	GF27.60-D-3012HAG
Engage gear range, function	GF27.60-D-3009HAG
Torque converter lockup clutch control, function	GF27.20-D-3002HAG
Torque converter lockup clutch control pressure, function	GF27.60-D-3019HAG
Working/lubrication/shift pressure, function	GF27.60-D-3024HAG
Control valve pressure, function	GF27.60-D-3017HAG