Mercedes-Benz ML320. Service manual - part 193

 

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Mercedes-Benz ML320. Service manual - part 193

 

 

 

2001 Mercedes-Benz ML320 

1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662

  

me 

 

Fig. 135: Shift From 1st To 2nd, Function (Second Gear Engaged)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
 

Aim  

Engage front multiple-disc clutch (K1), disengage front multiple-disc brake (B1). 

Operation  

1st Gear Engaged  

The end face of the 1-2/4-5 command valve (31a) is kept depressurized via the 1-2 and 4-5 shift solenoid valve 
(Y3/6y3). Via the 1-2/4-5 holding pressure shift valve (28a), working pressure (p-A) is applied to the front 
multiple-disc clutch (K1) is depressurized. See Fig. 133

Shift Phase  

Via the 1-2 and 4-5 shift solenoid valve (Y3/6y3), the shift valve pressure (p-SV) is directed onto the end face 
of the command valve 1-2/4-5 (31a). See Fig. 134. The 1-2/4-5 command valve (31a) is displaced and the shift 
pressure (p-S) coming from the 1-2/4-5 shift pressure shift valve (29a) via the 1-2/4-5 command valve (31a) is 
directed to the front multiple-disc clutch (K1). At the same time the front multiple-disc brake (B1) is subjected 
to overlap pressure from the 1-2/4-5 overlap regulating valve (30a). 

The B1 pressure acting on the end face of the 1-2/4-5 shift pressure shift valve (29a) is superseded by the 
working pressure (p-A). The increasing shift pressure (p-S) at the front multiple-disc clutch (K1) acts on the 
annular area of the 1-2/4-5 overlap regulating valve (30a). With an appropriate pressure level at the 1-2/4-5 
holding pressure shift valve (28a) this valve switches over. 

2nd Gear Engaged  

After the gear change is complete, the pressure on the end face of the 12-/4-5 command valve (31a) is reduced 
via the 1-2 and 4-5 shift solenoid valve (Y3/6y3) and the command value is pushed back into its original 
position. See Fig. 135. Via the 1-2/4-5 holding pressure shift valve (28a) working pressure (p-A) now reaches 
the front multiple-disc clutch (K1) via the 1-2/4-5 command valve (31a). 

The front multiple-disc brake (B1) is disengaged (depressurized). The spring in the 1-2/4-5 shift pressure shift 
valve (29a) pushes this into its original position. 

Operating Pressure, Function 
 
See OPERATING PRESSURE, FUNCTION

Shift Pressure, Function 
 
See SHIFT PRESSURE, FUNCTION

Modulating Pressure, Function 

 

2001 Mercedes-Benz ML320 

1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662

  

me 

 

 
See MODULATING PRESSURE, FUNCTION

Shift Valve Pressure, Function 
 
See SHIFT VALVE PRESSURE, FUNCTION

Lubricating Pressure, Function 
 
See LUBRICATING PRESSURE, FUNCTION

Regulating Valve Pressure, Function 
 
See REGULATING VALVE PRESSURE, FUNCTION.  

Limp-Home Mode, Function 

Operation  

In order to ensure a safe driving state and to prevent damage to the automatic transmission, the ECT control 
module (N15/3) switches to limp-home mode in the event of critical faults. A fault code assigned to the fault is 
stored in memory. 

All solenoid and regulating valves are thus de-energized. 

Effect  

The gear last engaged remains engaged.  

The modulating pressure and shift pressure rise to the maximum levels.  

The torque converter lockup clutch is switched off.  

In order to preserve the operability of the vehicle to some extent, the hydraulic control can be used to engage 
2nd gear or reverse:  

Stop Vehicle  

Switch Off Engine  

Move Selector Lever To "P"  

Wait At Least 10 Seconds  

Start Engine  

Move Selector Lever To "D": 2Nd Gear  

Move Selector Lever To "R"  

The limp-home function remains active until the fault is rectified or the stored fault code is erased. Sporadic 
faults can be reset via ignition OFF/ON. 

 

2001 Mercedes-Benz ML320 

1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662

  

me 

 

Upshift/Downshift Solenoid Valve, Location/Design/Task/Function 
 
See UPSHIFT/DOWNSHIFT SOLENOID VALVE, LOCATION/TASK/DESIGN/FUNCTION

Location/Task/Design/Function Of PWM Solenoid Valve, Torque Converter Lockup Clutch 
 
See LOCATION/TASK/DESIGN/FUNCTION OF PWM SOLENOID VALVE, TORQUE 
CONVERTER LOCKUP CLUTCH

Modulating Pressure Regulating Solenoid Valve, Location/Task/Design/Function 
 
See MODULATING PRESSURE REGULATING SOLENOID VALVE, 
LOCATION/TASK/DESIGN/FUNCTION

Shift Pressure Regulating Solenoid Valve, Location/Task/Design/Function 
 
See SHIFT PRESSURE REGULATING SOLENOID VALVE, 
LOCATION/TASK/DESIGN/FUNCTION
.  

Operating Pressure, Function 

The working pressure supplies pressure to the hydraulic control and transmission elements. The working 
pressure is the highest hydraulic pressure in the entire hydraulic system. The working pressure is regulated at 
the working pressure regulating valve in relation to the load and gear. All other pressures required for 
transmission control are diverted from the working pressure. 

Working Pressure Regulating Valve, Location/Task/Function 
 
See WORKING PRESSURE REGULATING VALVE, LOCATION/TASK/FUNCTION

Upshift/Downshift Solenoid Valve, Location/Task/Design/Function 
 
See UPSHIFT/DOWNSHIFT SOLENOID VALVE, LOCATION/TASK/DESIGN/FUNCTION

Shift Pressure Control Solenoid Valve, Location/Task/Design/Function 
 
See SHIFT PRESSURE REGULATING SOLENOID VALVE, 
LOCATION/TASK/DESIGN/FUNCTION

Multiple-Disc Brake, Location/Task/Design/Function 
 
See MULTIPLE-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION

Multiplate Clutch, Location/Task/Design/Function 
 
See MULTI-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION

 

2001 Mercedes-Benz ML320 

1998-03 AUTOMATIC TRANSMISSIONS Complete Transmissions - ML 320 - 722.662

  

me 

 

 

 

 

 

 

 

 

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