I have a 2010 VW Jetta that now displays “Err” when I turn on the cruse control toggle - It is an automatic and all the break lights work - How do I self diagnose and fix? Or is the something the tech wizards at VW will need to do? Not really looking forward to a $500.00 repair being that cruse control does not effect the car’s performance.
start with the owners manual, then google…
Google has nothing - I know hard to believe - I didn’t get an owner’s manual when I bought the car - I’m SOL until some VW tech head on this forum repy’s
Google search might be more effective using the words brake and cruise.
Nothing really there - especially RE: diagnosis - certainly lots of parts, but I rather not play “Where’s Waldo” with buying and replacing parts at random - If you know what I mean.
If you can do this yourself, consider checking switches on the brake and/or clutch pedals as applicable. Sometimes an out of adjustment clutch pedal or switch bobbling around in the mounting tabs can cause cruise issues.
The vast majority of time, simple things like that are often overlooked while the feeling of electrical nightmare doom approaches and the worst is assumed 
I Googled and found this,
forums.thecarlounge.com/showthread.php?5492001-2010-2-5-S-model-with-cruise-control-error-amp-EPC
ok4450 - Thanks - I will start at the brake pedal (don’t have a clutch pedal) - idiot666 - I did see this posting and didn’t quite known what to make of it - but like I say, I will start at the brake pedal and then go to the battery box. I will post my results in a day or so… thank you both.
My google searches ended up taking me here:
I also had the “err” show up each time cruise was turned on. I used the app that starts with “car” and ends with “ista” and had the following codes: P1698, Airbags 00532 (voltage low), Steering Wheel 00446 (under voltage).
I ended up changing out the cruise control stalk, and the issue was fixed. I opened up the old stalk and the blue wire had been severed. Hopefully this is helpful.