C3 Cruise Control
06-27-2018, 11:12 AM
#1
Advanced
Thread Starter
C3 Cruise Control
My '78C3 has cruise control but it is not working. Is it worth the effort to try and get it working again? I injured my right leg and it is painful to keep it in one position for an extended period of time. This limits the distance I can drive to shows. I would appreciate any advice on diagnosing the issue and whether it's worth it to repair it. It would make the car "whole" again. Thank you.
06-27-2018, 12:16 PM
#2
Melting Slicks
I have an 80, and i have to trouble shoot mine yet. Could be a fuse to start, could be the transducer. I like the feel of the gas pedal under my foot, there is no room in this car to rest your legs, so may as well keep your foot on the gas.
06-27-2018, 04:48 PM
#3
Instructor
My cc would not maintain a set speed. It turned out to be the transducer internals were corroded and would not spin freely. The transducer location is tight, but the cc works perfectly now.
Theres a decent diagnostic page in the service manual, especially if your switch is defective
Theres a decent diagnostic page in the service manual, especially if your switch is defective
My '78C3 has cruise control but it is not working. Is it worth the effort to try and get it working again? I injured my right leg and it is painful to keep it in one position for an extended period of time. This limits the distance I can drive to shows. I would appreciate any advice on diagnosing the issue and whether it's worth it to repair it. It would make the car "whole" again. Thank you.
06-27-2018, 04:50 PM
#4
Team Owner
You could fix the existing cruise system; or you could install a new aftermarket all-electronic cruise system and retain the stock switch stalk on your steering column. Rostra makes these kits and the signal is generated by little magnets mounted to your driveshaft, which provide pulse signals to a small magnetic pickup. The process is not complicated, and the result is a rock-steady constant speed with same switches as the original GM unit had.
There is a detailed troubleshooting chart for diagnosing problems with the old GM system. You can probably find a copy on the internet somewhere. It provides orderly steps to check out each portion of the system...and does it in the right order. Many common fixes for the GM system are inexpensive and simple; or you can just throw money at it and buy a new transducer, etc.
If it were me, I would troubleshoot the existing system until I found it was going to be costly or a lot of trouble to repair.
There is a detailed troubleshooting chart for diagnosing problems with the old GM system. You can probably find a copy on the internet somewhere. It provides orderly steps to check out each portion of the system...and does it in the right order. Many common fixes for the GM system are inexpensive and simple; or you can just throw money at it and buy a new transducer, etc.
If it were me, I would troubleshoot the existing system until I found it was going to be costly or a lot of trouble to repair.
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jim-81 (06-28-2018)
06-27-2018, 05:15 PM
#5
Former Vendor
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My '78C3 has cruise control but it is not working. Is it worth the effort to try and get it working again? I injured my right leg and it is painful to keep it in one position for an extended period of time. This limits the distance I can drive to shows. I would appreciate any advice on diagnosing the issue and whether it's worth it to repair it. It would make the car "whole" again. Thank you.
http://repairs.willcoxcorvette.com/w...iagnostics.pdf
Willcox
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jim-81 (06-28-2018)
06-27-2018, 11:23 PM
#6
Advanced
Thread Starter
Thanks Grumpy,
06-28-2018, 07:11 AM
#7
Burning Brakes
Is your speedometer working? If it is not then it will be at least the transducer that needs changing.
06-28-2018, 09:26 AM
#8
Safety Car
You could fix the existing cruise system; or you could install a new aftermarket all-electronic cruise system and retain the stock switch stalk on your steering column. Rostra makes these kits and the signal is generated by little magnets mounted to your driveshaft, which provide pulse signals to a small magnetic pickup. The process is not complicated, and the result is a rock-steady constant speed with same switches as the original GM unit had.
There is a detailed troubleshooting chart for diagnosing problems with the old GM system. You can probably find a copy on the internet somewhere. It provides orderly steps to check out each portion of the system...and does it in the right order. Many common fixes for the GM system are inexpensive and simple; or you can just throw money at it and buy a new transducer, etc.
If it were me, I would troubleshoot the existing system until I found it was going to be costly or a lot of trouble to repair.
There is a detailed troubleshooting chart for diagnosing problems with the old GM system. You can probably find a copy on the internet somewhere. It provides orderly steps to check out each portion of the system...and does it in the right order. Many common fixes for the GM system are inexpensive and simple; or you can just throw money at it and buy a new transducer, etc.
If it were me, I would troubleshoot the existing system until I found it was going to be costly or a lot of trouble to repair.
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Philgran (06-28-2018)
06-28-2018, 10:42 AM
#9
Melting Slicks
I had a look at mine last night, i have a 3 wire transducer with only 2 terminals connected? the "Light" terminal has no wire.. Should my 80 be a 2 wire, or do i need to go hunting the harness for the third wire.
06-28-2018, 10:44 AM
#10
Melting Slicks
I am dreading this. I will have to pull the drivers seat out to be able to look up under the dash to see what switches are mounted to the brake pedal.
06-28-2018, 11:27 AM
#11
Race Director
I have repaired many and got them to work and it is a 50/50 split on if it is the hose that goes to the vacuum switch at the brake pedal is bad...or the actual switch will not hold vacuum.
I have taken apart the transducers and fixed them many times.
Regardless...the information that WIllcox posted in POST #5 is what you need.
:"Grumpy427'.
My 1980 wiring diagram only show a 2 wire connector going to your transducer OTHER THAN the black ground wire that is bolted to it.
DUB
I have taken apart the transducers and fixed them many times.
Regardless...the information that WIllcox posted in POST #5 is what you need.
:"Grumpy427'.
My 1980 wiring diagram only show a 2 wire connector going to your transducer OTHER THAN the black ground wire that is bolted to it.
DUB
06-28-2018, 04:23 PM
#13
Race Director
I have no clue on that due to not being able to really get a good look of what you have installed.
DUB
DUB
06-28-2018, 04:29 PM
#14
Melting Slicks
well the speedo works, and i have an open cct across the 2 pins of the transducer. So my next step will be to look at the brake pedal switches and the fuse panel.
06-28-2018, 07:06 PM
#15
Team Owner
What are the symptoms? I assume that it will not activate, but does the cruise light illuminate on the dash? Have you checked to see if turning the CC switch to ON provides 12vdc to the system? Sometimes, the details in the symptoms can lead you directly to the root cause.
06-28-2018, 07:13 PM
#16
Melting Slicks
There is no cruise lite on the dash. This is confusing as i have a transducer with a "Lite " terminal on it and no wire? Everyone so far said mine should be a 2 wire one. Kind of hard to start when the components may be wrong to start with. Be running around in circles.
06-28-2018, 09:35 PM
#18
Advanced
Thread Starter
Thank you
06-29-2018, 09:48 AM
#19
Race Director
There is no cruise lite on the dash. This is confusing as i have a transducer with a "Lite " terminal on it and no wire? Everyone so far said mine should be a 2 wire one. Kind of hard to start when the components may be wrong to start with. Be running around in circles.
DUB
06-29-2018, 10:05 AM
#20
Race Director
A 1981 wiring schematic shows the transducer has THREE wires.
Look at the brake switch area and see if it has a light blue and pink with a black stripe on it.
You should also have another switch at the brake pedal area that has an ORANGE and WHITE wire going to it
DUB
Look at the brake switch area and see if it has a light blue and pink with a black stripe on it.
You should also have another switch at the brake pedal area that has an ORANGE and WHITE wire going to it
DUB