Justsomeguy01

Hi all,

Does anyone have information on how to troubleshoot cruise control on a 1977? I have the button on my steering column, when I press it my speedometer indicated speed dips a couple miles per hour momentarily but nothing else happens.

Are there any schematics for how the system works floating around out there?

stevedinino

PM me your email address. There is a GM publication that details the system - operation, troubleshooting and repair. I’ll send it to you.

bruiser

Make sure the servo linkage is good. There is a ball chain under the rubber boot on the sevo that broke a couple times on mine.

bmotojoe

The GM Cruise Control Systems manual has some very good troubleshooting guidelines to go by.
In that manual page 1-1 of General Operations section use Figure 1-2 for the switch control.
Figure 1-2
3. Full Release, Cruise Remains Engaged
2. Partial Release To Engage.
1. Depress Fully To Disengage
The 1977 Corvette Electrical Troubleshooting Manual uses a little different terminology:
A, B, or C
A=3. in Figure 1-2 and is called Cruise in the 77 Troubleshooting Manual
B=2. in Figure 1-2 and is called Engage in the 77 Troubleshooting Manual
C=1. in Figure 1-2 and is called Trim in the 77 Troubleshooting Manual
When pressing the 1977 Corvette Cruise Switch ONLY halfway you engage the cruise circuit if the vehicle is at or over 30 MPH.
Let's say you want to slow down from 70 MPH to 55 MPH and keep the Cruise engaged, you would then fully depress and hold the switch until you reach 55 MPH then release, this function is called Trim.
It will NOT fully disengage the cruise circuit until the vehicle falls below the minimum speed of 30 MPH.