77 Cruise control problem
Thread Starter
Instructor
Joined: Nov 2006
Posts: 122
Likes: 0
From: TX
77 Cruise control problem
When I push the cruise control switch part way in to actuate the cruise control, it activates, but accelerates continuously until I tap the brake.
If I push to switch all the way in, it will stop accelerating and coast, and then accelerate again when I release it.
I have taken a look in the control unit (is it called a transducer?), and found that there was a switch that was not making contact. I cleaned the switch, and actuated the solenoid in the unit with 12V applied to both terminals.
I don't see anything else obviously wrong in the unit. But I also don't see how it regulates the vacuum to the servo, so I don't have a clue how it works.
Vacuum lines all look OK, and the speedometer works, so the speed info is going through the unit.
Anyone fixed this problem? Or have any ideas on what I should do next?
If I push to switch all the way in, it will stop accelerating and coast, and then accelerate again when I release it.
I have taken a look in the control unit (is it called a transducer?), and found that there was a switch that was not making contact. I cleaned the switch, and actuated the solenoid in the unit with 12V applied to both terminals.
I don't see anything else obviously wrong in the unit. But I also don't see how it regulates the vacuum to the servo, so I don't have a clue how it works.
Vacuum lines all look OK, and the speedometer works, so the speed info is going through the unit.
Anyone fixed this problem? Or have any ideas on what I should do next?
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
The cruise control on 1979 and older GM vehicles never worked very well. I installed a new transducer on my 1979 L-82 when I first bought it as it was eating speedometer cables. The speed would vary from 5 MPH below where I set it to 5 MPH above (varied 10 MPH). Frustrating at best and an irritation to drive. Take off the transducer throw it in the trash. Buy a speedometer cable for a non-cruise control car. The wiring for the cruise control unplugs. Throw that away too and you won't spend a lot of money for nothing.
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
That's what I did, solved the problem immediately. 
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
The rebuilt cruise control unit I bought from Ecklers, which I installed on my '77, has worked flawlessly for 2 years now. It maintains speed like the speedometer needle is nailed down. I take 2-3 road trips a week--I need it! If yours doesn't work, it just needs to be fixed--not trashed.
Last edited by PhotoVette1; Jun 15, 2008 at 09:29 AM.
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
Maybe you had better listen to PhotoVette1. Sounds like his cruise control works well. Myself, I installed everything new and could not get mine to work very well after spending a lot of money on it. So out of frustration I got rid of it. I do know the 1980 and newer cruise controls work better.
