Automatically Shifted Manual Transmission/Transaxle: Testing and Inspection

DIAGNOSIS OF DOUBLE CLUTCH TRANSMISSION

General Description
The gearbox is fitted with 2 clutch pressure sensors, 2 speed sensors for the clutch speed, 4 shift rod sensors and 1 oil temperature sensor. Based on these sensors the diagnosis is checking if the gearbox is working right. For controlling the gearbox there are 6 pressure regulators (closed loop) and 2 magnetic valves (on/off) necessary.
With the pressure regulators the 2 clutches, the cooling, the system pressure and the direction of the shift rods are controlled. The magnetic valves are need for the selection of the shift rod.

1. Electrical Diagnosis
The valves are controlled by the ATIC80. It reports the errors SCG, SCB and OL via SPI to the processor. If the ATIC80 does not deliver useful data additional a plausibility check is done.
The diagnosis is made over all valves at the same way.

2. Plausibility Checks

2a. Ratio control diagnosis
The ratio of the gearbox is checked when no shifts occur and the vehicle outputshaft speed is above a calibrateable threshold that defines that the vehicle is moving. Below this threshold the output speed of the torque transferring clutch is compared with the output speed of the transmission.

2b. Shift rod diagnosis
Based on the driver action the movement of the shift rods were checked by the shift rod sensors with several plausibility checks. The checks are if the shift rod is sticking, wrong shift rod is moving or no shift rod is moving.

2c. Clutch diagnosis
This function should detect clutch slips. The slip of the torque transferring clutch is monitored based on the engine speed signal and the clutch speed.

The closing and opening of the clutches are monitored by the clutch sensor. The measured clutch pressure must have the expected pressure levels after a certain time.

In the filling period it will be checked that the pressure will drop after the fast fill impulse. In the opening period it will be checked that the pressure drops down below the touch point and in the open period it will be checked the pressure will not be raised. The measured pressure will also be compared by the target pressure.