Peter
Member
My newly acquired A2 (my 50th car, my 14th Audi, my 3rd A2, my first diesel A2) has cruise control installed but it will not work. I had cruise control in my previous (petrol) A2 so know what to look for in analysing the problem.
I have checked (using VCDS) the
- sensors for clutch and brake pedals
- stalk switches: ON, OFF, cancel, +/RESUME and -/SET
Sensors and switches show their proper operation (measuring blocks 006 and 022 for diesel cars, petrol cars use 066); bits toggle as expected and so I assume the wiring to be OK.
Now there are two issues.
1) The ECU part number in VCDS does not show the additional "G" to confirm cruise control activation. I tried to activate the cruise control using login 11463. No effect. Measuring block 006 shows cruise control as activated: ON=1.0 OFF=0.0 (de-activated=255.0).
2) My ELM327 OBD dongle and the Torque app on my smartphone show the speed as 0 (speed is correctly displayed in other cars). Also the ECU shows the speed in measuring block 006 and 027 as 0 km/h.
Clearly, if the ECU "thinks" I am doing 0 mph, it will assume I am in first gear and cruise control will not work.
So the problem boils down to: why is my speed invisible to the ECU and to the OBD dongle?
Note: the 90hp TDI has no G22 speed sensor. Speed is derived from the 4 ABS sensors on the wheels, reported over the CANbus by the ABS/ESP-controller. The ECU and the instrument panel are the other controllers on this bus.
The instrument panel drives the speedometer and shows actual speed. Is it there that the 4 wheel speeds are converted to one car speed?
Does the ECU perform the same calculation to derive the car speed from the wheel speeds? Or is car speed transmitted by the instrument panel?
Any help, suggestions greatly appreciated!
I have checked (using VCDS) the
- sensors for clutch and brake pedals
- stalk switches: ON, OFF, cancel, +/RESUME and -/SET
Sensors and switches show their proper operation (measuring blocks 006 and 022 for diesel cars, petrol cars use 066); bits toggle as expected and so I assume the wiring to be OK.
Now there are two issues.
1) The ECU part number in VCDS does not show the additional "G" to confirm cruise control activation. I tried to activate the cruise control using login 11463. No effect. Measuring block 006 shows cruise control as activated: ON=1.0 OFF=0.0 (de-activated=255.0).
2) My ELM327 OBD dongle and the Torque app on my smartphone show the speed as 0 (speed is correctly displayed in other cars). Also the ECU shows the speed in measuring block 006 and 027 as 0 km/h.
Clearly, if the ECU "thinks" I am doing 0 mph, it will assume I am in first gear and cruise control will not work.
So the problem boils down to: why is my speed invisible to the ECU and to the OBD dongle?
Note: the 90hp TDI has no G22 speed sensor. Speed is derived from the 4 ABS sensors on the wheels, reported over the CANbus by the ABS/ESP-controller. The ECU and the instrument panel are the other controllers on this bus.
The instrument panel drives the speedometer and shows actual speed. Is it there that the 4 wheel speeds are converted to one car speed?
Does the ECU perform the same calculation to derive the car speed from the wheel speeds? Or is car speed transmitted by the instrument panel?
Any help, suggestions greatly appreciated!