Mercedes 7G Tronic 722.9 Transmission Control Module TCM Conductor Plate Failure
This issue commonly occurs in Mercedes vehicles equipped with the 7G-Tronic automatic transmission, identified by gearbox code – 722.9. Symptoms include prolonged holding in one gear followed by abrupt shifting, resulting in a rough and jerky gear change.
Initially intermittent, this problem escalates to a permanent state if left unresolved. It stems from the breakdown of the TCM conductor plate internally, impeding the monitoring of the input shaft’s rotational speed by the control module. Consequently, it fails to gauge torque converter slippage, leading to ineffective torque clutch lock-up, hindering smooth gear changes or even gear selection in severe cases.
Common Faults:
- Engine management light illuminated (in most cases but not always)
- Gearbox goes into “Limp Mode” with reduced power
- Intermittently failing to change gear
- “Sticking” or staying in one gear
- Failing to select a gear
When attempting to diagnose this issue within cars the fault codes can be a very useful tool. While the common symptoms are a useful tell, fault codes generally can give a more accurate read as to the issue with the car.
Common Fault Codes
- P2207 Component Y3/8n3 (Output speed sensor (VGS)) is defective – upon request
- P2206 Component Y3/8n3 (Output speed sensor (VGS)) is defective – upon request
- P2550 Component Y3/8n3 (Output speed sensor (VGS)) is defective – upon request
- 0717 – the signal from component Y3/8n1 (turbine speed sensor, VGS) is not available
- 0718 – the component Y3/8n1 (turbine speed sensor, VGS) is defective,
- 0722 The signal from component Y3/8n3 (Output speed sensor (VGS)) is not available – upon request
- 2201 – the component Y3/8n2 (internal speed sensor) is defective
