I've reviewed numerous posts both on here and RL re this and still don't have a clear picture of what might be wrong. Car has been in a shop for the last 9 months. Finally got it back and the cruise didn't work. The light on the dash wouldn't even come on. Porsche dealer found that when the new ecu was installed, the tech didn't activate the cruise control. They turned it on for me, but sadly even that didn't get the cruise to work (though the dash light did come on with the indicator stalk). What's odd is that a few days later, the switch on the stalk wouldn't activate the light on the dash anymore. Well, fast forward to last night and the light came back on. In no event did the cruise actually work but i know it won't work without the light (ie the system is powered). Seems now to be 2 issues. One powering the system seems like it could be a loose wire someplace and then the issue with the cruise still not working is something else. Thoughts?

 

if the cruisecontrol is activated over obd port....it must be possible to switch on ...if not maybe the switch is def, cabel , connector ore a fuse.....

you need a diagnostic tool to check the system... brake pedal switch, clutch switch ect.

in your case one question be allowed? what was the reason for a new ecu?

btw....the cruisecontrol is coded at the instrument...

 

Could be a number of things.

Clutch pedal switch, brake pedal switch or 3rd brake light bulb is out. Those are the common mechanical issues that might cause cruise control to not work. Less common is a blown fuse or broken cruise control stalk. All these can be tested with a multi-meter.

If it's not mechanical, then it could still be a coding issues. Cruise control needs to be enabled in the DME *and* the instrument panel. Durametric enthusiast will only do the instrument panel and dealers sometimes for get to enable both.

I've been chasing the same issue for a while. Narrowed it down (although I haven't got it to a dealer to verify yet) to the cruise control needing to be enabled in the DME and instrument panel.

 

for me not comfortable for checking it with a multimeter, brake pedal switch has two circuits and many other things are possible to check with a diagnostictool in a short time...

i dont prefer to much climbing in the car....especially to the brake pedal switch smile


yes, cruise control is programmed in ecu and has to be activated at instrument (normaly never loose this features)