Over the weekend I replaced the heater core in my car, now the cruise isn't working as it should. If you set the cruise, it immediately speeds up about 5 miles an hour faster than where I set it and then it will slow down and speed back up, repeatedly. I have looked at everything and all I can come up with is either there is a vaccuum leak or the amplifier is crapping out. Any thoughts on this?
I thought these cars used an electric servo on the cruise control instead of the older vacuum controlled? I'm not positive, but I'm pretty sure.
However, a vac leak could still cause the surging. Also, I had a TPS not functioning correctly on my Mark VIII that caused that kind of behavior though not quite as drastic as what you're describing!
I replaced the TPS when I bought the car, so its less than a month old. It doesn't surge like that unless you use the cruise. My buddy has a parts car. I may grab the box off of it too, among the other pieces I want.
I got it figured out. I checked and rechecked all of the vaccuum lines, and nothing. That led me to recheck the amplifier box under the hvac housing. There was one wire that had gotten pulled out of the harness connector that I hadn't seen. I pushed that back in, and the cruise works.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
TCCoA Forums
1.5M posts
26.9K members
Since 2002
A forum community dedicated to Ford Thunderbird, Mercury Cougar and Lincoln Mark owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, maintenance, and more!