Mercedes 722.9 transmission

The Mercedes 722.9 7G Tronic transmission has seven forward gears and two reverse gears made possible by two planetary gear sets and a Ravigneaux gearset that essentially combines multiple planetary gearsets into a single unit. Four multi-disc brakes and three multi-disc clutches are used to control the gears. Mercedes 7G Tronic conductor plate problems and 7G Tronic TCM problems prevent the computer from controlling these gears as it needs to, resulting in several symptoms. These include:

  • Noticeably delayed shifts
  • Extremely harsh upshifts and downshifts
  • Failed gear engagement
  • Limp mode (the transmission gets locked into a single forward gear to prevent further damage to the transmission)

What is a Mercedes 722.9 conductor plate and 722.9 TCM?

The Mercedes 722.9 conductor plate, sometimes referred to as the 722.9 VGS, is mounted to the transmission’s valve body. It contains the transmission control module, which has the speed sensors integrated into the 7G Tronic TCM top. The speed sensors monitor the rotational speed of the transmission input shaft so that the computer knows how fast the vehicle is going. This data helps determine when to shift gears and relays these commands to the eight 722.9 solenoids that are mounted in the conductor plate itself. Because of the complicated electronic controls, each 722.9 conductor plate must be programmed to work with its installed vehicle. Mercedes Benz won’t sell you a brand-new 722.9 conductor plate and TCM unless you are an authorized Mercedes dealer. However, you can buy a rebuilt 722.9 conductor plate for considerably less money.

What causes Mercedes 722.9 conductor plate and 722.9 TCM problems?

Because the speed sensors are integrated into the 7G Tronic TCM, the entire unit has to be replaced or rebuilt when one of them fails. The sensors’ information allows the TCM to determine the exact slippage of the torque converter so it can provide a smooth gear change. But when the TCM or 722.9-speed sensors begin to fail, the transmission operation will become harsh and erratic. If the 722.9 VGS problems are not addressed immediately, the computer will transmit it into Limp Mode, which restricts it to a single forward gear (2nd) to prevent damage to other transmission parts.

Common Mercedes Conductor Plate Fault Codes

  • 0717 – The signal from the Y3/8N1 turbine speed sensor is not available
  • 0718 – The Y3/8N1 turbine speed sensor is defective
  • 2201 – The Y3/8N2 internal speed sensor is defective
  • 0722 – The Y3/8N3 output speed sensor is not available
  • 0721 – The transmission output speed signal is implausible when compared to the wheel RPM signal
  • 2766 – Excessive RPMs have occurred at the Y3/8N2 internal speed sensor
  • 2767 – The signal from the Y3/8N2 output speed sensor is not available
  • 2768 – The signal from the Y3/8N2 internal speed sensor is defective

Replacing a Mercedes 722.9 Conductor Plate

Before you buy a Mercedes 722.9 conductor plate, you must get the correct version. They actually made three: Mercedes VGS1 was typically used on vehicles made between 2004-2007. The Mercedes VGS2 and Mercedes VGS3 versions were used on later models. Each 7G Tronic TCM conductor plate is engraved with a number that will tell you which version you have. However, the Mercedes TCM is programmed to only work with your specific vehicle’s ECU and immobilizer system. You can buy used and have us virginized, or we can order new from the Dealer, and we can program the new TCM.

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