Mercedes introduced its new 5-speed automatic transmission in 1996, replacing the older 4-speed models. The transmission was used on some models in Europe until 2020, which really speaks to its reliability and durability. In the US diesel market, it was in the E-class, the Jeep Grand Cherokee WK, the T1N Sprinter, and the NCV3 Sprinter with the OM642 engine.
This 5-speed transmission is known by a few different names. Mercedes refers to it as a 5G-tronic class and a type 722.6. You may also hear people refer to it as a WA580 or W5A580. In this case, the “W” indicates an automatic transmission that uses a hydraulic torque converter, the 5 is for the 5 forward gears, the “A” is for automatic, and the 580 is the maximum input torque capacity in Newtons. The name NAG1 was only used in reference to Domestic Chrysler products. NAG1 stands for New Automatic Gearbox 1st generation. These different names all refer to the same transmission.
The transmission is electronically controlled with a lock-up clutch in the torque converter. The gears are hydraulically activated using the electronic controls. The shift transitions and lockup-apply strategy work seamlessly. Acceleration is smooth, and the engine power is not interrupted by the shifts. All of this is controlled through TCM and PCM programming.
The powertrain programming is engineered to save fuel whenever possible and provide power on demand. The torque converter clutch is usually applied between 35 and 50 miles an hour under moderate acceleration. Depending on throttle opening and engine load, it can either be fully applied or partially applied. Under light throttle, the torque converter clutch can be commanded “on” as early as 2nd gear. On deceleration, the torque converter is partially applied in order to bring the engine RPM down to about idle speed. The TCC command and injector shut-off mode commanded by the PCM allows the vehicle to save fuel when coasting or coming to a stop. The fuel injectors are commanded on, and the torque converter clutch is commanded off before the vehicle comes to a complete stop.
Repair Solutions
Like any component, there are common problems, but fortunately, there are also easy fixes that cost far less than a new transmission or vehicle. Difficulty shifting especially out of 2nd gear could be caused by a faulty conductor plate. Although this repair may seem daunting at first it is only an additional couple of steps more than changing the transmission filter.
Another common issue we see is leaking around the 13-pin adapter. Although this leak in itself is not a major issue, if it continues to leak fluid it can get on the wiring harness and will eventually damage the TCM. You can inspect this when doing a fluid change, and it may be good to have one on hand.
If shifting problems continue, you may need to replace the solenoids in the transmission.
