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I have fixed all the vacuum leaks that I could find underneath the intake manifold. I replaced the 3 way check valve for cruise, but that seemed to not make a difference.
When I set a speed the car will constantly apply some throttle then let off, apply throttle, then let off. It repeats this cycle the entire time I have the cruise set. Is there a computer that controls the cruise? Could it be the stalk on the steering column?
I don't know what to look at. Any suggestions are appreciated.
Bob has your fix. My CC responded exactly as yours. A while back when I adjusted my TB cable, I didn't get the pin back into the exact hole (or, my cable adjustment required another hole for the cruise).
Bob has your fix. My CC responded exactly as yours. A while back when I adjusted my TB cable, I didn't get the pin back into the exact hole (or, my cable adjustment required another hole for the cruise).
Can I get a picture of what you guys are talking about?
From the earlier posts they make it sound like their cable was too tight. If I am understanding this correctly, it appears mine is on the loosest setting. Could it be too lose?
What I understand is this vacuum diaphragm actually moves in not out correct?
I tried moving the cable for the cruise control and it made 0 difference for how well the cruise worked.
What is the best way to troubleshoot this?
The issue is I can set the cruise and while driving it will open the throttle for a second then snap shut, it will repeat this process the entire time it is on. I can accerlate with the cruise no problem using the control stalk.
Vacuum activated electrical switches. They are actually a very common cause of cruise control problems.
Where can these be found? Are they actually by the brake/clutch pedal assembly inside the cabin or somewhere else? Is there a fix for them or do they have to be replaced?
I would like to mention that both my AC and heat work just fine.
Last edited by billy mild; Mar 9, 2015 at 07:30 PM.
Where can these be found? Are they actually by the brake/clutch pedal assembly inside the cabin or somewhere else? Is there a fix for them or do they have to be replaced?
I would like to mention that both my AC and heat work just fine.
Switches are in the cabin at the pedals. There is a trouble shooting procedure for them, but I don't have my manuals anymore, so can't help you any further.
It may be a bad connection in the cruise control stalk, cruise control stalk connector under dash or the dash as others have mentioned.
Have you tried the simple things like the cruise control vacuum switch at the brake pedal, try a simple adjustment each way and see.
However that just cuts the cruise control while going over a bump, it should not resume without your input.
Unplug the connector and reconnect, check the vacuum hoses for cracks. if the vacuum is intermittent due to cracked vacuum hoses that can explain your issues.
First thing you should buy once you have a corvette is the shop manual. See below.
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Rent a vacuum (MightiVac) device from your local parts store and attach it to the rubber tube that leads from your brake pedal to the engine compartment. If it does not hold pressure then you simply need to find the leak.
My leak was a hole in the rubber line where it connects to the vacuum reserve ball (#16 in the diagram) that sits under the left headlight. I clipped off the last 1/4" and reattached it - fixed! Been a long time so I cannot remember whether it was on my old 91 or a previous C4.
Here is a diagram of the 85 and later cruise control system.
Cruise Control Issues
