Cruise Control No Longer Works! Help!

[SavoBusa]

My cruise control on my 2002 PT Cruiser Touring Edition: sometimes it works, sometimes it doesn't. When it doesn't (which is most of the time), the CRUISE light comes on, but it goes off after a few seconds and then won't come back on until the car is turned off and back on. It's been this way for a few years now. Another peculiar symptom is that I recently had to change the battery wiring harness (I have 135,000 miles and the car was outside for most of its life). After I changed the harness (the old cables were toast, corroded), the cruise control started working again, perfectly. However, that only lasted one week. Now it is back to doing the same symptom as before. When it does work, it isn't reliable and will literally go off whenever it gets ready, such as hitting a bump in the road or going up a small hill. I checked the vacuum and the connection to the cruise control vacuum unit. Everything looks good to go. Any ideas?

[MX-5]

A quick recording of the datastream will show what input is lost when it fails.
That should be a simple diagnosis to find the faulty part.

[saldagus]

I had the same problem. It's the connector under the Vacuum solenoid (on the firewall on the passenger side). Its either loose. or has some corrosion.