Mercedes-Benz W203 automatic transmission conductor plate and jerking when cold
What causes a W203 CDI automatic to jerk or hunt revs when cold?
Common causes are an old conductor plate, the TCC solenoid (the valve that controls torque converter lock-up) and a leaking bushing at the bulkhead connector. Old oil or the wrong oil level can also cause the symptom, so check the oil level and condition first.
Why is the condition of the bulkhead connector and the control box important?
Oil leaking from the bulkhead connector can travel along the wire into the electrical connector and the control box. The box is in the cabin, in the front passenger footwell under the carpet. An oily connector is replaced, and the box is cleaned with electrical cleaner and dried. The new bulkhead connector must not rotate while being tightened.
How is the TCC solenoid replaced?
The gearbox does not need to be removed: the oil pan is taken off and the aluminium valve body is unscrewed. The solenoid is on top of the valve body, and it is worth replacing the seal of the electrical connector at the same time. The job takes about 1-2 hours. The conductor plate is plastic, so be careful with the plug.