Mercedes-Benz 722.6 (NAG1) Automatic Transmission
Posted: Wed May 25, 2011 4:29 am
Dear All,
Hello. My name is Michael. I am posting from Cyprus.
I am planning to do an extensive conversion on a Mercedes-Benz G-Class (1985 280GE LWB), including the installation of an MB M104 inline-6 3.2l, 24v engine coupled to an MB 722.6 5-speed automatic transmission.
My plan is to use the MegaSquirt MSIII (v3.57) + MS3X for the engine control and the GPIO – MegaShift for the transmission control.
I have done a lot of research on both the engine and the transmission but I still have a lot more things to do.
The Mercedes-Benz 722.6 (or NAG1 for Neue Automatikgetriebe 1) transmission is an electronically controlled gearbox mated to a lock-up clutch equipped torque converter. It first appeared in the mid-90s and has been in use on Mercedes-Benz passenger cars and vans ever since. Its’ variants also found their way into Jaguar, Porsche and Chrysler/Jeep/Dodge cars. Some of the transmission variants can handle up to 900 Nm of torque ex-works.
I have managed to gather the following technical information for the variant 722.611 (W5A330) which is rated at 330 Nm of input torque:
Ratios:
1st Gear 3.93
2nd Gear 2.41
3rd Gear 1.49
4th Gear 1.00
5th Gear 0.83
Reverse Gear 1 -3.10
Reverse Gear 2 -1.90
Electrical Connections:
The transmission bears a 13-pin electrical connector with which it is controlled. The wires are 0.8 mm in diameter (20 gauge). Pin 5 on the connector is not used, so there are 12 live contacts.
Early transmissions also had and extra output speed sensor (4-pin connector, 3 pins live) which was feeding the signal through a ballast to the Transmission Control Unit.
Signals provided by the transmission
2 RPM sensors (namely n2 and n3). They seem not to be measuring input / output speed directly. They rather measure internal transmission rotating components speed. They are both measuring on 60-teeth patters and they seem to be of hall-effect type sensors (the are internally wired with 3 wires). Sensor n2 provides its’ output to pin 3 whilst sensor n3 provides its’ output to pin 1. They are both grounded via pin 12 and are supplied with current via pin 7.
Oil temperature sensor (namely b1). It is a temperature dependent resistor connected to pins 4 (signal) and 12 (ground). It is connected in line with the starter lockout contact switch (see below). Temperature information is thus only available when the selector is not in ‘P’ or ‘N’. Sensor calibration data is available.
Starter Lockout Contact (namely s1). It is a switch which is connected in line with the temperature sensor. It is open (i.e. no current flows) when the selector lever is in ‘P’ or ‘N’ and closes in all other selector lever positions.
Output Speed Sensor (namely B49). Separate from the 13-pin connector. No further information available yet.
Actuators on the transmission
The transmission has 6 solenoid valves which control its’ hydraulic circuits.
Modulating pressure control solenoid valve (namely y1). Seems to be PWM controlled. It is connected to pin 6 (which is the common supply for all solenoids) and pin 2 (ground). It is controlled via pin 2.
Shift pressure control solenoid valve (namely y2). Seems to be PWM controlled. It is connected to pin 6 (supply) and pin 10 (ground). It is controlled via pin 10.
1-2 and 4-5 shift solenoid valve (namely y3). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 13 (ground). It is controlled via pin 13.
3-4 shift solenoid valve (namely y4). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 11 (ground). It is controlled via pin 11.
2-3 shift solenoid valve (namely y5). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 8 (ground). It is controlled via pin 8.
Torque converter lockup PWM solenoid valve (namely y6). It is PWM controlled. It is connected to pin 6 (supply) and pin 9 (ground). It is controlled via pin 9.
Selector Lever
Latest models are equipped with a touch-shift selector lever (P-R-N-D and ‘+’ & ‘-‘) with mechanical linkage for P-R-N-D and which provides signals via CAN bus for upshift/downshift.
Earlier models (like the first ML-Class) equipped with the 722.6 transmission were fitted with a voltage coded selector lever (P-R-N-D-4-3-2-1) with mechanical linkage for P-R-N-D and voltage output via a Gear Recognition Switch. No further information yet.
I am planning to do a logging/analysis of the actual electrical signals between the transmission and the transmission control unit in the next couple of weeks.
I will post the results here as soon as they are available.
From my point of view there are is a fundamental difference with the other transmissions currently supported by MegaShift. The difference lies in the presence of two pressure controlling solenoids instead of one.
I know that the basic design of the 722.6 family of transmissions has remained the same over the years. Of course lots of technical improvements have been introduced.
I presume that once MegaShift is configured to run the particular transmission, any other 722.6 transmission will be just a matter of tuning.
I would like to hear you comments and opinions on the subject.
Regards
Michael
Hello. My name is Michael. I am posting from Cyprus.
I am planning to do an extensive conversion on a Mercedes-Benz G-Class (1985 280GE LWB), including the installation of an MB M104 inline-6 3.2l, 24v engine coupled to an MB 722.6 5-speed automatic transmission.
My plan is to use the MegaSquirt MSIII (v3.57) + MS3X for the engine control and the GPIO – MegaShift for the transmission control.
I have done a lot of research on both the engine and the transmission but I still have a lot more things to do.
The Mercedes-Benz 722.6 (or NAG1 for Neue Automatikgetriebe 1) transmission is an electronically controlled gearbox mated to a lock-up clutch equipped torque converter. It first appeared in the mid-90s and has been in use on Mercedes-Benz passenger cars and vans ever since. Its’ variants also found their way into Jaguar, Porsche and Chrysler/Jeep/Dodge cars. Some of the transmission variants can handle up to 900 Nm of torque ex-works.
I have managed to gather the following technical information for the variant 722.611 (W5A330) which is rated at 330 Nm of input torque:
Ratios:
1st Gear 3.93
2nd Gear 2.41
3rd Gear 1.49
4th Gear 1.00
5th Gear 0.83
Reverse Gear 1 -3.10
Reverse Gear 2 -1.90
Electrical Connections:
The transmission bears a 13-pin electrical connector with which it is controlled. The wires are 0.8 mm in diameter (20 gauge). Pin 5 on the connector is not used, so there are 12 live contacts.
Early transmissions also had and extra output speed sensor (4-pin connector, 3 pins live) which was feeding the signal through a ballast to the Transmission Control Unit.
Signals provided by the transmission
2 RPM sensors (namely n2 and n3). They seem not to be measuring input / output speed directly. They rather measure internal transmission rotating components speed. They are both measuring on 60-teeth patters and they seem to be of hall-effect type sensors (the are internally wired with 3 wires). Sensor n2 provides its’ output to pin 3 whilst sensor n3 provides its’ output to pin 1. They are both grounded via pin 12 and are supplied with current via pin 7.
Oil temperature sensor (namely b1). It is a temperature dependent resistor connected to pins 4 (signal) and 12 (ground). It is connected in line with the starter lockout contact switch (see below). Temperature information is thus only available when the selector is not in ‘P’ or ‘N’. Sensor calibration data is available.
Starter Lockout Contact (namely s1). It is a switch which is connected in line with the temperature sensor. It is open (i.e. no current flows) when the selector lever is in ‘P’ or ‘N’ and closes in all other selector lever positions.
Output Speed Sensor (namely B49). Separate from the 13-pin connector. No further information available yet.
Actuators on the transmission
The transmission has 6 solenoid valves which control its’ hydraulic circuits.
Modulating pressure control solenoid valve (namely y1). Seems to be PWM controlled. It is connected to pin 6 (which is the common supply for all solenoids) and pin 2 (ground). It is controlled via pin 2.
Shift pressure control solenoid valve (namely y2). Seems to be PWM controlled. It is connected to pin 6 (supply) and pin 10 (ground). It is controlled via pin 10.
1-2 and 4-5 shift solenoid valve (namely y3). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 13 (ground). It is controlled via pin 13.
3-4 shift solenoid valve (namely y4). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 11 (ground). It is controlled via pin 11.
2-3 shift solenoid valve (namely y5). Seems to be on/off controlled. It is connected to pin 6 (supply) and pin 8 (ground). It is controlled via pin 8.
Torque converter lockup PWM solenoid valve (namely y6). It is PWM controlled. It is connected to pin 6 (supply) and pin 9 (ground). It is controlled via pin 9.
Selector Lever
Latest models are equipped with a touch-shift selector lever (P-R-N-D and ‘+’ & ‘-‘) with mechanical linkage for P-R-N-D and which provides signals via CAN bus for upshift/downshift.
Earlier models (like the first ML-Class) equipped with the 722.6 transmission were fitted with a voltage coded selector lever (P-R-N-D-4-3-2-1) with mechanical linkage for P-R-N-D and voltage output via a Gear Recognition Switch. No further information yet.
I am planning to do a logging/analysis of the actual electrical signals between the transmission and the transmission control unit in the next couple of weeks.
I will post the results here as soon as they are available.
From my point of view there are is a fundamental difference with the other transmissions currently supported by MegaShift. The difference lies in the presence of two pressure controlling solenoids instead of one.
I know that the basic design of the 722.6 family of transmissions has remained the same over the years. Of course lots of technical improvements have been introduced.
I presume that once MegaShift is configured to run the particular transmission, any other 722.6 transmission will be just a matter of tuning.
I would like to hear you comments and opinions on the subject.
Regards
Michael