98 E300 Cruise Control
 

Hi I have a 98 E300td the cruise control works up to 65mph, but kicks off anything above that. What could be the problem.
Thanks for any help Chago:confused:

Could be a whole laundry list of parts, but it's probably just one. You might want to find someone with a scanner to see if there are any internal complaints. AutoZone scanners needn't apply; you'll need the real deal.

Tires!
 

Make certain your tires are all the same size...I was running slightly smaller tires in the rear last winter and it would cause my cruise to quit because it senses the different spinning speeds and once a threshold has been met it cuts out to prevent the cruise from causing what it thinks is a skid...check this first before spending money or time elsewhere.

Marty thanks for the info I had just put new rear tires on 215/55R16 and the fronts are 225/55R16 and thats when the problem started.
Chago

BINGO! You can send me a check for the diagnosis ;)

If you want it to work right then all 4 wheels have to be the same size.

I knew that they needed to be the same size per the owner's manual, but did not know that the cruise control would shut off if they are slightly different. My manual only warns about the traction control system, but it would not surprise me at all to see the same behavior.

Yeah, they apparently have the CC monitor the wheel speeds too. It's bad to have different sized wheels on the car for a number of reasons...for me I was trying to save a few dollars by mixing two pairs of snow tires last winter but it turns out that was a bad idea...so I found out (the hard way) that the cruise control will cut out when you run it with different sized tires...just been waiting for someone to post a thread with the same symptoms so I could look smart :D