Cruise Control Issue
Thread Starter
Racer
Joined: Mar 2015
Posts: 306
Likes: 20
From: Greenville SC
Cruise Control Issue
I have searched previous threads but could not find this problem mentioned. I have a 79 L48 automatic w/ cruise control. When I push the button to engage it does not work. If I pull slightly on the turn signal lever while pushing the button, the cruise engages but only accelerates. It's like it gets a shot of nitrous. The cruise disengages when I press the brake.
Any suggestions???
Any suggestions???
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Here is the factory cruise manual from the 1978 Service Manual, it should be the same as the set up on your car. I suspect you have a turn signal lever shorting out which is not good news. http://repairs.willcoxcorvette.com/w...iagnostics.pdf
Willcox
Willcox
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
You may have two different problems.
First, any of the three wires at the cruise control switch were shorted to the column (ground) you would pop the low amp GAUGES fuse. The red and blue wires have +12V ignition power while the third (brown) wire gets +12V when the switch is pushed to either position. (Note these are the colors of the wires in the column--they change at the firewall connector. At the speed control unit (transducer) the blue wire is now brown and the brown wire is now white.
Since the cruise control didn't have a "RESUME" function in '79 I see utterly no way for the speed to increase due to an electrical fault in the switch or the circuit. The only thing that could cause run-away operation is a defective transducer.
I would suspect some sort of mechanical problem in the direction signal lever and a transducer in need of service or replacement. If you search you can find instructions for cleaning/checking the transducer. Remanufactured units are easily available and not particularly expensive.
First, any of the three wires at the cruise control switch were shorted to the column (ground) you would pop the low amp GAUGES fuse. The red and blue wires have +12V ignition power while the third (brown) wire gets +12V when the switch is pushed to either position. (Note these are the colors of the wires in the column--they change at the firewall connector. At the speed control unit (transducer) the blue wire is now brown and the brown wire is now white.
Since the cruise control didn't have a "RESUME" function in '79 I see utterly no way for the speed to increase due to an electrical fault in the switch or the circuit. The only thing that could cause run-away operation is a defective transducer.
I would suspect some sort of mechanical problem in the direction signal lever and a transducer in need of service or replacement. If you search you can find instructions for cleaning/checking the transducer. Remanufactured units are easily available and not particularly expensive.
