vanster

Is there a thread on cruise control? I just replaced my current module with a rebuilt unit and it does a wonderful job of going full throttle. In my car with 440# of torque it is gobs of fun but I don't think this is how it should work.

jschiller

I found this thread some time back. If you need to send the controller off for repair, Kris will do it for you at a modest price. I'm sending mine off next week.

https://rennlist.com/forums/928-foru...agnostics.html

jwillman

I used the WSM troubleshooting steps to validate the system up to the controller. It validated all the other components and once I had the controller rebuilt it works perfectly even with all other components being nearly 40 years old!

vanster

This is great. thank you.
Must say flipping on the cruise control and the car jumps to flat out not exactly cruise control or maybe I'm missing something. Even more exciting for the car in front of me

Christopher Zach

The problem is the output FET on the cruise controller is shorted, thus when the CC turns on it applies full power to the servo with hilarious results.

Now, that FET is only rated to 1a so it is *possible* that your cruise control servo is sticking, the magnet in it draws more than 1a in current, and the CC fuse (which is too big of course, this is Porsche) is saved by the CC unit sacrificing itself. Might want to check the current draw of the CC servo unit, it should be a couple of hundred ma at 12v tops.

Wish Porsche had fused things properly. Oh well.

mkhargrove

I bought my car half way across the country. Flew to get it with a girl I was dating. I drove the first 400 miles or so, then in the mountains of Colorado she wanted her turn. She set the cruise. Away we went. Yes, fun times.

vanster

I had the CC unit rebuilt and it still does the same thing. What's next?

Christopher Zach

Weird. At this point I would probably sit down with the servo for a bit. Get a constant current power supply, set to 500ma, and see if it causes the car to accelerate when 12v is applied.