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Discussion Starter · #1 ·
Just bought a 1965 Malibu Convertible that came with Chevy Cruise Control set-up. System is not function properly and I some help in regards to parts availability and maybe repairs control unit. Any sites in regards to wiring set-up and testing of system. Thanks Fred
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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to the top, anybody know about these units? speedometer cable driven, straight mechanical.
 

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Yes, I am familiar with these units...at least the Cadillac version from the same era, which I believe uses the same basic design and control device.

Working from memory here, The basic control module is a speedometer cable driven master control module which manages the throttle lever position. It does this by balancing a pair of contact closure actuators which control a small bi-directional electric motor in the module. that motor drives a worm gear which in turns drives a gearset attached to the throttle position arm. This arrangement gains continuous positional reference from a combination of two inputs. First reference is the speedo cable speed rotating a spring loaded governor, which is comparing its contact closure status to the position of the Bowden cable's contact closure. the Bowden cable is connected to the speed selector wheel inside the car. The actuator motor is "balanced" when the rotating governor and the Bowden cable setting are in equilibrium. Both switches OFF. If the car slows, the governor weights change position, closing the switch A, and actuating the motor to open the throttle. As the car increases speed, the governor weights rotate faster, until they break contact, and the device again reaches equilibrium. At this point the contact closure opens and equilibrium is reached.

If the driver increases speed via the speed wheel, the contact closure B actuates the motor, moving the throttle arm and increasing throttle unit the governor rotational speed reaches equilibrium again.

If the driver decreases speed via the speed wheel, the circuit reverses the polarity to the worm gear motor, moving the actuator in the opposite direction and slowing the car until equilibrium is again achieved.

Besides the control module and the speed control wheel, there is also a brake override switch and a three position speed selector switch, and a linkage from the control module actuator arm motor, out to the throttle linkage at the carb. The device is held "on" by a self energizing relay in the control module, even when in equilibrium. Touching the brake pedal opens the B+ to that relay, turning the system "off". A mechanical spring loaded throttle override is built into the control unit, which allows the operator to overpower the control module, simply by using sufficient foot peal pressure.

It's been about eight years, but I completely restored one of these to full and correct function in my 64 Caddy. They work quite well, when properly operating and calibrated. I used to have a schematic and diagnostic notes. As I recall, the control modules are "not user serviceable", but I fixed mine...which had a bad contact closure. Trying to remember who built the control module - it was a GM subsidiary but the name escapes me at the moment.
 

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This is on my 65.




Took a couple of years to get it to work right, but love it now. Driven thousands of miles with it. The parts, especially the switch, are extremely brittle and touchy. It was made by perfect circle. A Dealer added option. Real hard to find parts for. If you can find a 1965 Chevelle Chassis Service Manual, it has the service manual in it. I have it scanned into my computer somewhere, so send me a PM and I can e-mail it to you.

Good luck, it is one of the cool factors of my car, I have never seen another working one on a 65. :cool:
 

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Yes, perfect circle! holy smokes, couldn't call that one up...thanks!

Guess I'm getting old. :)

Yes, this is the same unit as featured on Cadillacs as a factory option through 63 at least. I've been all inside the device in your picture, and somewhere here I have notes and schematics, etc.
 

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Discussion Starter · #6 ·
Thanks for your info. Have found a service manual and their is a section on the cruise control unit. It also outlines the steps to take to test to see if things are working properly. I believe the control unit needs to be serviced as it seems the slide bar does not return smoothly. Thanks for your help.
 

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Discussion Starter · #7 ·
Thanks for your reply. You mention that you serviced your control unit, any pointers as to how to go about taking apart and making sure all the parts are working correctly. Any help greatly appreciated. Thank you
 
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