P1569/ 17977 - Implausable Signal Cruise Control


Registered User
Hi there i have posted something simular to this previosly but didnt have a fault code number...

Anyway i have replaced the clutch switch and still having the same issue.

This is the only code coming up on my S3 8L APY 2000 - i recently replaced the pre cat lambda and this fault is now cleared. i had the faults reset after this and my Cruise control worked for around a day, i turned the engine off locked it and left it parked for a few hours came back and it was still working... today got in the car and it wasnt working again... just went and got it scanned again and this is the only code that returned so i would rule out the lambda fault as it has not returned.

According to other searches the best search i have found is this:

it mention possibly about the break switch, however in other threads it also metions it could be the stalk.
as it was in full working order and the stalk seems to be in good condtion (as in the switch still clicking comfortably on the stalk). i dont want to speand out on a new stalk...

Is it worth replacing the brake switch to rule it out as it is relativly cheap ? I also dont understand what they mean by "block 66" or "Bit's"?
Any other advise would be gratefull



Registered User
Anyone have any idea ...?? Im gunna replace the brake switch in the next week hopefulky this does it


Registered User
Hi thanks i have had a gander at your link ill be doin the brake switch and if that fails ill possibly look into that link further and find someone local (Cornwall) that can help Cheers


Registered User
Hi, I have just fitted CC to my S3 AMK and code 17977 keeps appearing and I can't get it to work.

After some investigation with VCDS, every switch seems to work fine (proper bits changes when looking at block 066): clutch, brake (x2), stalk on/off, +/res and -/set. CC is enabled and I can see the G-letter in the 01 engine screen. I also performed throttle body alignment.

If I hold +/res down for more than 0.5s the code appears. I think that the problem might be with the +12V wire, I have connected it to fuse 5. Bad connection or busted wire maybe.

When the stalk is at ON position, the last bits are 0001 and 0000 when OFF. Could someone confirm if also second to last bit should be 1 (0011) when CC is set ON and 12V is fed, vehicle stationary, power on, engine not running? If I take the fuse 5 out, the bits still changes when stalk buttons are pressed. The fuse is ok because climate control dies when I take it out.



Registered User
Got this finally working a few days ago, when I had time and motivation to check all the wiring and connections. The problem I had was bad wire connection at the ECU plug (I had extended the cable that came with the kit, the wires were a bit too thick).

This is for any future reference, VCDS is very helpful for diagnosing the problem (block 066, check ross-tech link a few posts above):
  • If all bits are 0 and are not toggling at all, it's probably the 12V feed or busted stalk.
  • If clutch, brake or brake light bits are not toggling, it's probably broken pedal sensor or brake light.
  • If all the bits are toggling, but pushing buttons on stalk causes 17977 error code, check your wiring to ECU.
When everything is properly installed and the stalk is at ON position, last bits should be 0011.

Just made my first 200km trip with the CC and it's awesome, really smooth operation. No more tired right foot :)