1997 MERCEDES-BENZ ML500 oil

Fig. 103: Temperature Sensor, Function
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Operation
The temperature of the transmission oil has a major influence on the shift time and thus on the shift quality. It is
possible to optimize the gear shifts in all temperature ranges by detecting the oil temperature. See Fig. 103.

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 178 © 2006 Mitchell Repair Information Company, LLC.

The transmission oil temperature sens or (Y3/6b1) is connected in series with the starter lockout contact
(Y3/6s1). The temperature signal is tr ansmitted to the ETC control module (N 15/3) only the dry-reed contact of
the starter lockout contact (Y3/6s1) is closed.
Selector Valve, Location/Task
Fig. 104: Selector Valve, Location/Task
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Selector Valve, Location

The selector valve (52) is located in th e valve housing of the shift plate (2a). See Fig. 104
.
Selector Valve, Task

Distributes pressure to the appropriate h
ydraulic components according to the selector lever position

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMI SSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 179 © 2006 Mitchell Repair Information Company, LLC.

Fig. 106: Torque Converter Lockup Clutch, Function
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Operation
When actuated by the ETC control module (N15/3), oil pressure controlled by the torque converter lockup
PWM solenoid Valve (Y3/6y6) is directed through the input shaft (1) to the pressure chamber behind the piston
(16d). See Fig. 106
. The piston presses the clutch pack (16c) together and allows torque to be transferred
directly between the impeller (P) and turbine wheel (T). The torque converter lockup clutch is activated in 5th,
4th and 3rd gears in relation to the engine speed and engine load.
AUTOMATIC TRANSMISSION, FUNCTION
Transmission without touch shift. 722.6 in MODEL 163, 170, 202, 208, 210.
Transmission 722.6 in MODEL 129, 140.
Automatic transmission 722.6 is an electronically controlled 5-speed transmission with a lockup clutch in the
torque converter.
The ratios for the gear stages are achieved by three planetary gear sets. The 5th gear is designed with a step-up
ratio as an overdrive.
Shifting is initiated electronically. The gears are shifted by the corresponding combination of three
hydraulically actuated multi-plate brakes, three hydraulically actuated multi-disc clutches and two mechanical
freewheels.
Basically automatic transmission 722.6 with electronic control offers the following advantages:
Reduced fuel consumption
Improved shift comfort
More favorable gear steps as a result of 5 gears
Enhanced life and reliability
Reduced servicing costs
The electrohydraulic control unit is bolted onto the bottom of the transmission housing. The end of the
transmission is formed by an oil pan made of sheet steel.
The oil pressure for the converter lockup clutch and center multiple disc clutch is supplied via holes in the input
shaft. The oil pressure to the rear multiple-disc clutch is routed through the output shaft. The lubricating oil is
supplied and distributed by additional bore holes in both shafts. All bearing points of the gear sets as well as
freewheels and shift elements are supplied with lubricating oil.
The parking lock gear and drive flange are connected to the output shaft by gearing.
Freewheels F1 and F2 optimize shiftin
g. The front freewheel (F1) rests against the stator shaft extension on the

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 183 © 2006 Mitchell Repair Information Company, LLC.

transmission side and connects the sun gear of the front planetary gear set to the transmission housing in the
locking direction.
The torque converter housing and transmission housing are made of a metal alloy. They are bolted together and
centered via the outer multiple-disc carrier of the multiple-disc brake B1. A coated intermediate panel seals the
two components.
The oil pump and outer multiple-disc carrier of the front multiple-disc brake are bolted to the converter housing.
The mechanical part consists of the propeller shaft, output shaft, a sun gear shaft and three planetary gearsets
which are coupled together.
In transmissions for powerful engines, the planetary gearsets have 4 planetary gears, while for less powerful
engines the front and rear planetary gear system has three planetary gear wheels. The stator shaft is pressed into
this and is secured against turning by a spline.
The rear freewheel (F2) connects the sun gear of the center planetary gear set to the sun gear of the rear
planetary gearset in the locking direction.
The electrohydraulic control unit consists of the shift plate made of light alloy for hydraulic control and an
electronic control unit.
The electrical control unit consists of a supporting body made of plastic in which the electrical components are
combined. The shell is screwed to the shift plate. Conductor tracks which are integrated into the shell, connect
the electric components to a plug connector. This 13-pin plug connector forms the connection with the vehicle-
side wiring harness and with the ETC 5 (electronic transmission control) control module (N15/5) via a bayonet
lock.
Automatic Transmission, Location Of Mechanical Components

See AUTOMATIC TRANSMISSION, LOCATION OF MECHANICAL PARTS
.
Automatic Transmission, Location Of Electrical/Electronic Components

See AUTOMATIC TRANSMISSION, LOCATION OF ELECTRIC/ELECTRONIC
COMPONENTS.
Automatic Transmission, Location Of Hydraulic Components

See AUTOMATIC TRANSMISSION, POSITION OF HYDRAULIC COMPONENTS
.
Automatic Transmission, Location of Components, Floor Shift

See AUTOMATIC TRANSMISSION, LOCATION OF COMPONENTS, FLOOR SHIFT
.
Automatic Transmission, Selector Lever Positions


2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 184 © 2006 Mitchell Repair Information Company, LLC.

Fig. 108: Selector Lever Positions
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
AUTOMATIC TRANSMISSION, FUNCTION
Transmission With Touch Shift 722.6 In Model 163
Transmission 722.6 is an electronically controlled 5-speed transmission with a lockup clutch in the torque
converter.
The ratios for the gear stages are achieved by 3 planetary gearsets. The 5th gear is designed as a low-rev gear
with an overdrive ratio.
Shifting is initiated electronically. The gears are shifted by the corresponding combination of 3 hydraulically
actuated multi-disk brakes, 3 hydraulically actuated multi-disk clutches and 2 mechanical freewheels.
The oil pump as well as the external plate carrier of the front multi-disk brake are bolted to the torque converter
housing.
The mechanical part of the transmission 722.6 consists of a drive shaft, output shaft, a sun gear shaft and 3
planetary sets which are coupled to each other.
The electrohydraulic control unit is screwed onto the transmission housing from below. The end of the
transmission if formed by an oil pan made of sheet steel.
The oil pressure of the torque converter lockup clutch and center multi-disk clutch is supplied via bore holes in
the drive shaft. The oil pressure to the rear multi-disk clutch is supplied via the output shaft. The lubricating oil
is supplied and distributed by additional bore holes in both shafts. Oil is supplied to all bearing points of the
gearsets as well as to the freewheels and shifting elements.
The parking lock gear and drive flange are connected to the output shaft by gearing.
Basically transmission 722.6 with electronic control offers the following advantages:
Reduced fuel consumption.
Greater ease of shifting.
Favorable spacing by 5 gears.
Long service life and high reliability.
Low maintenance costs.
The torque converter housing and transmission housing consist of a light-metal alloy. Both housings are bolted
together and are centered via the external plate carrier of the multi-disk brake at the front. A coated intermediate
panel seals the two components.
Freewheels F1 and F2 optimize shifting. The front freewheel F1 is supported on the extension of the stator shaft
on the transmission end and connects in the lockin
g direction the sun gear of the front planetary gearset with the

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 189 © 2006 Mitchell Repair Information Company, LLC.

Location/Task/Design/Function Of Freewheel

See LOCATION/TASK/DESIGN/FUNCTION OF FREEWHEEL
.
Function Of Gear Shift (With Touch Shift)
Transmission with touch shift.
On transmission 722.6 the electrohydraulic control unit converts the electric signals going out from the
electronic transmission control (EGS) into hydraulic signals.
Faults occurring in the ETC control unit (N15/3) are handled by the limp-home system. The limp-home system
is designed so that the driver can reach a Service Operation even under extreme conditions.
Selector lever position "P", "R", "N" and "D" are transmitted by the electronic selector lever module control unit
(N15/5) on the Controller Area Network bus class C (engine compartment) (CAN-C) and in parallel to this by
means of a shift rod to the range selector lever at the transmission end. By touching or holding the selector lever
towards "+" or "-" the shift range is pre-selected and displayed in the instrument cluster (A1) until an upshift of
transmission 722.6 is possible.
Function Of Gear Change

See FUNCTION OF GEAR CHANGE
.
Emergency Default Mode, Function

See LIMP
-HOME MODE, FUNCTION.
Function Of Manual Drive Mode Selection

Oil Level Control, Function

See OIL LEVEL CONTROL, FUNCTION
.
Torque Converter Lockup Clutch Control, Function

See FUNCTION OF TORQUE CONVERTER LOCKUP CLUTCH CONTROL
.
Function Of Gear Shift (Without Touch Shift)
On transmission 722.6 the electrohydraulic control unit converts the electric signals going out from the
electronic transmission control (EGS) into hydraulic signals.
Faults occurring in the ETC control unit (N15/3) are handled by the limp-home system. The limp-home system
is designed so that the driver can reach a Service Operation even under extreme conditions.
Selector lever position "P", "R", "N" and "D" are transmitted by the electronic selector lever module control unit

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 224 © 2006 Mitchell Repair Information Company, LLC.

(N15/5) on the Controller Area Network bus class C (engine compartment) (CAN-C) and in parallel to this by
means of a shift rod to the range selector lever at the transmission end. By touching or holding the selector lever
towards "+" or "-" the shift range is pre-selected and displayed in the instrument cluster (A1) until an upshift of
transmission 722.6 is possible.
Function Of Gear Change

See FUNCTION OF GEAR CHANGE
.
Emergency Default Mode, Function

See LIMP
-HOME MODE, FUNCTION.
Oil Level Control, Function

See OIL LEVEL CONTROL, FUNCTION
.
Torque Converter Lockup Clutch Control, Function

See FUNCTION OF TORQUE CONVERTER LOCKUP CLUTCH CONTROL
.
Function Of Gear Change
Operation
Every gear change is triggered by the electronic transmission control (ECT). Each shift sequence is assigned a
control block. Each of these contains one overlap regulating valve, one holding pressure shift valve, one shift
pressure shift valve, one common command valve and one electromagnetically actuated switchover valve
(upshift/downshift solenoid valve).
Actuation of the solenoid valve switches over from stationary mode to the shift phase.
When the gear change is complete the solenoid valves are no longer actuated as the different gears are subject to
a self-hold function in stationary mode.
Shifting "N" To "D" (1st Gear), Function

See SHIFTING N TO D (1ST GEAR), FUNCTION
.
Shifting N To D (1st Gear), Function
Transmission 722.6 As Of 1.7.96

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 225 © 2006 Mitchell Repair Information Company, LLC.

(B3). The further sequence of the switch-on process is as when engaging the rear multi-disc brake.
Residual Pressure
To avoid air getting into the hydraulic system, which causes a deterioration in shift quality, the line system
remains filled with oil in steady-state operation of the automatic transmission.
Function Of Shift From 1 To 2

See SHIFT FROM 1 TO 2, FUNCTION
.
Shift From 1st To 2nd, Function
NOTE: No mating surface on the piston of the center multi-disc brake (B3).

2001 Mercedes-Benz ML320
1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662
me
Saturday, October 02, 2010 3:15:28 PMPage 230 © 2006 Mitchell Repair Information Company, LLC.