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DALLAS MERCEDES TRANSMISSION REPAIR SHOP
The Mercedes-Benz Transmission
You might be one of the fortunate people to own or drive a Mercedes Benz. Owning one of the worlds better built vehicles however will not exempt you from experiencing transmission problems like the rest of us.
Although we see less of these vehicles in for repairs, which only meanâ€™s that there are less of them on the road.
Mercedes has used different variations of transmissions depending on year and model, as an example we will list just a few of these and focus more on the one of the most common on the road today.
The following list is just some of the variations used.
722.0 Three Speed
722.1 Four Speed/4 Bolt Pan
722.2 Four Speed/4Bolt Pan
722.3 Four Speed/6Bolt/Large Case
722.4 Four Speed/6Bolt/Small Case
722.5 Five Speed Overdrive
722.6 Six Speed Overdrive
722.9 Seven Speed Overdrive
One of the most common of these is the 722.6, so will discuss that model for simplicity.
The 722.6 is also called a NAG1 (New Automatic Gearbox 1st Version) or also called a 5G-Tronic. This transmission is electronically controlled, which means shift by wire.
According to Mercedes Benz, this transmission is sealed for life, which is why there is no dipstick to check your fluid level.
Mercedes Benz however in recent years has published article AP00.20-U-12081B calling for a transmission fluid and filter change at 39000 miles. This was added into the 2007 and later model year â€œMaintenance Bookâ€. The 2006 model year book has a recommendation for maintenance checks for high mileage vehicles at 143000 miles.
The 2009 model year added the EVERY 40,000 mile Fluid & Filter Change. Most 2009 models however use the 722.9 transmission.
When servicing the transmission, Mercedes recommends the use of genuine Mercedes fluid; however this can be subsuted for fluid that is on their approved list of acceptable fluids.
Common Problems That Occur
As with any other transmission, these transmissions also have their own common problems that unless addressed immediately, can cause major problems.
- the majority of leaks come from the 13 Pin Electrical connector and the shifter mechanism bellow.
The 13-Pin connector can leak either internally or externally. In some, the leak will even wick up the harness to the ETC (Electronic Control Module) causing the Module to short out as well. Mercedes has an updated connector now available for this condition.
Most models have a cup holder near the shifter, where of course, out of habit we place our drinks in. We sometimes get a little careless and might even spill a little on the shifter. Well, located under that shifter is a Shift module, which does not function as it should when it has coffee or other liquid splashed on to it. This can cause your check engine light to come on, cause you to have â€œcodesâ€ for gear ratio errors and also put you into â€œlimp modeâ€, meaning youâ€™re running only on the gear that was engaged at the time.
Removing and cleaning the module will sometimes, but not always eliminate the problem. Even if you are able to do a good cleaning, the computer will have to be checked, cleared and reset to be sure that was all the damage done.Obviouisly, you donâ€™t want to continue driving with this malfunction as serous internal damage may occur.
- Limp Mode
- occurs when the Transmission Control Module (ETC) detects an active or intermittent problem and then wont allow gear shifting in order to avoid serious internal damage.
Limp mode has two classifications, the first being â€œMechanical-Hydraulic emergency running Modeâ€. In this mode, the transmission locks into third gear or the â€œLastâ€ known good gear.
The second type of Mode is â€œElectric emergency running Modeâ€. In this mode, whatever gear was engaged is retained and a fault code stored. When you turn off the ignition and restart again, the transmission is locked into second and reverse only. When you try to shift from park to reverse or drive or even neutral, you will a harsh engagement cluck.
This does not necessarily mean you need to replace your transmission, as in a majority of cases a simple replacement of â€œthe Conductor Plateâ€ is all that will be required. The conductor plate is attached to the top of the valve body and consists of two sensors and six solenoids. The two speed sensors are usually what fails, and when they do the ETC does not know the input or output speeds and wont know what gear to engage the transmission. The Speed sensors cannot be replaced separately, so the whole plate must be replaced.
A proper diagnosis from one our certified technicians will determine what type of problem you may be experiencing to determine if the repairs required will be a minor repair as the one described above.
We have the experience and knowledge to solve all of your transmission needs.