Guys and Gals,
New here and I am having problems with the cruise(or automatic speed control). I'm not even getting a green light when I push the wakeup button. It does come on during startup though, then it's gone. I have tried all the combinations to wake it up...no green light. I was trying to find the fuse for it, if there is one. No title for cruise control on any fuse diagram I can find. Maybe Porsche uses a secret code symbol for it? Next plan is to pull every one of them and check them all. Any hints?
Drive safe

 

What year car? Stick or tiptronic (or PDK?)

 

It's a 2008 w/Tiptronic and paddles.

 

Did you “upgrade” the tail lights to LED units? I thought I read that might cause an issue with cruise control.

 

i have Dectane LEDs on both my 997.1 cars and no issues with cruise functioning properly.

If the green light won't come on when it's powered on from the stalk, I'm guessing blown fuse. Easiest way to test fuses is with a meter in continuity mode where it beeps when there is continuity. J7st touch the points of the leads to the slots in the back of the fuse and listen for the beep - thus way you don't have to pull each one to check it.

 

I had aftermarket LED tail lights installed in my 2008 TT for less than a month before switching back to OE incandescent lights.

My cruise control failed in a very similar manner to what was described by the OP after I installed the LEDs. I reinstalled my OE tail lights, and the issue remained. My car ended up needing the dealer to reactive the cruise control system. Once this was done, I never had another issue.

My failure may have been a coincidence with the installation of the LED tail lights, and it may not. I know that this is an issue with the 996 series cars when they install LED tail lights. I'm not sure if the issue exists on some 997.1 cars or not.

 

For some reason the Turbos do require additional resistors when changing to the LED tails also (these are usually built into the aftermarket lights now), but I don't know why they're only needed on the Turbos, but in any case, it's possible that the turbos are more sensitive to the change to LEDs and if the cruise control failure is related, that may also be more likely to occur on the turbo cars.

 

Dennis,
I haven't, but the previous owner may have. I honestly have never noticed. I'll check this weekend when I get back home. Fuse check time too! Might be a simple fix? Fingers crossed!
Thanks, Guys

 

Reviving this thread as I just bought a 997TT and have the same problem. Cruise control doesn't work and the green light will not come on when you push the button but does light up when the car is started. I have a 6sp with stock taillights. I have checked all the fuses and replaced the red switch at the clutch pedal but still not working. Any other thoughts?

 

Tried everything I knew, no CB problems, had to take to Porsche and have them reflash the CC module. No problems since. I do have LEDs. New problem! (Is't there always a new problem?) Only making 4 psi under throttle. No strange noises and no out-of-range indications. Runs ok, if you want to drive it like a sissy. Nah! Get the Lightning out....

 

Follow up on my cruise control problem. I feel stupid to admit this, but my cruise control actually does work! The light in the dash is burnt out, I just never tried to use it since the cruise light never came on. I asked my shop to replace the light and they pulled the cluster only to report back that the light is an LED soldered into the cluster and not replaceable unless they send out the cluster for repair. Not worth the hassle for me, at least cruise works.