Audi A4 GRA AJM - Solved Problem

Hello and happy Easter.

Two weeks ago, I had a GRA (adaptive cruise control) system installed in my Audi A4. I purchased the kit, including the steering wheel lever and pre-wired harness, from the internet (genuine Audi parts). Unfortunately, it's not working as it should. Setting the speed works well, and it maintains the speed. However, when I try to adjust the speed using the buttons, the GRA often disengages completely during acceleration, reaching about 80%. Also, it doesn't always re-engage. This doesn't happen during deceleration, but I often have the problem that the GRA doesn't respond to every button press.
Now, I wanted to check the wiring and switch commands via measurement block 6 using VAG-COM. However, this is not possible! When accessing the measurement block, the following image appears – see AJM_Measurement Block 6.
I checked this with an AFN engine, and the measurement block (image AFN measurement block 6) looks exactly as I would expect it to.
Is it possible that the switch positions in the Audi can only be queried via the CAN bus, or is there another measurement block available?
I would be grateful for any tips.

Best regards, and have a wonderful Easter celebration.

Kai-Uwe

Hello Kai-Uwe,

Could you please check what is displayed in measurement block 22 of the engine control unit? Hopefully, you have this measurement block, as it shows the switches/contacts of the GRA lever.

Quote:

022,0,Switch states. 022,1,GRA,Deactivation status,0 = GRA disabled / 1 = GRA active (off) / 9 = GRA active (on) 022,2,GRA Status,,see Labelfile ; 000000 - OFF ; 000011 - ON ; 000111 - SET ; 001011 - RES (Reset) ; 000001 - OFF (pressed)

Most often, the GRA lever is defective when unusual behavior occurs.

Best regards, Rainer.

Quote:

However, if I want to change the speed using the buttons, the GRA (gravitational assist) drops out by about 80% during acceleration.

That could potentially trigger a slipping clutch.

Hello you two,

Thank you for the quick response and help. Rainer, your tip about measurement block 22 was spot on: I have read the following data:

Measurement block 22; Field 1; Field 2.

Switch 2 to "OFF".
zoomed: 1.0; 000000

Switch 2 to "OFF".
before the locking point: 1.0; 000001

Switch 2 to "ON": 9.0; 000011.

Switch 2 to "ON": 9.0; 001011

Switch 1 pressed: 9.0; 000111.

Brake pedal pressed: 2.0; 010011

Clutch depressed: 9.0; 100011.

So, actually, that's exactly how it should be. Therefore, the GRA lever should be working correctly.
Now the question is why it seems to be disengaging more often, especially during acceleration. I hope it's not a slipping clutch, as I haven't seen any signs of that so far. Also, the car is almost exclusively driven on long distances, and I generally avoid aggressive starts that could cause a slipping clutch.
I'll test all the gear settings while driving again tomorrow and post the results on the forum.

Best regards.

Kai-Uwe

Hello Rainer, hello everyone,

To conclude this topic, I'd like to briefly present the solution.
to announce the problem.
As Rainer correctly suspected, it was the lever; it had a loose connection, or, although it was new, it was already worn out!
After replacing the GRA lever, the GRA functioned perfectly!

Best regards and thank you for your support.

Kai-Uwe

That was fast, and thank you for the feedback.