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5 minute cruise actuator fix

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
Some of you folks may already be familiar with this but just in case it might help save some time for somebody I'll go ahead and post this.

Looks like I've fixed my cruise control on my '96 after messing around with it off and on for a few months. It would work great for a few minutes after engaging it, then slowly start losing speed. I could help it with the gas pedal and it acted like it just wasn't getting enough vaccuum. The puzzling part was that if it was vaccum related why wouldn't it have the symptom all the time? And why would it work again for a short while after kicking it off for a few minutes? Seemed like an electrical problem to me, something was heating up. I suspected a problem inside the computer. The other day I Tee'd into the vac supply line next to the actuator with a line/gage and ran it inside the car so I could watch the vacuum change as I operated it. I found that the vacuum swings wildly when its operating but would generally stay around 17 inches Hg. Then when the cruise quit holding speed it would simultaneously drop to about 8~9 inches Hg and stay there. Obviously related to vacuum...or so I thought. I took the back half of the actuator off the assembly (the electrical part) and disassembled it on the bench hoping to find some buggered rubber seal or worn part. Didn't find anything wrong with it. Looked like a pretty simple and robust design BTW. As I was reassembling it I realized what was probably happening to cause the problem. There are 6 vertical electrical connections that appear as tiny vertical bars, 2 each on the ends of each of the three electrical coils that control the valves. These bars contact little bulges in the electrical traces on the facing piece of white plastic, the traces then continue on to the electrical connector on the back of the actuator. The bulged traces just butt up against the bars on the coils to make the connection. As the coils operated and heated up the plastic housing warped enough to break, or make only a partial connection, at one or more of them. There are three self threading screws that pull each pair of these connections together located just under the actuator cover. As I reassembled the thing I just made sure these were snug. The cruise works perfectly now.

The upshot of all this is to say that all I really needed to do was take the back cover off (two small Torx screws) snug up the three torx screws visible under the cover and put the cover back on, 5 minute fix max. You don't even need top remove the electrical connector as it comes off with the back cover. If your cruise is intermittent you might want to give this a try. To take it one step further you might also want to remove those three torx screws just mentioned, remove the white plastic connection board and use some steel wool on each of those bulged spots to renew the contact points.

regards

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1

1984C4

Guest
Thanks alot. I'll file that into the brain matter for later. When I got my car the cruise did not work either. Turned out it was missing a screw that someone did not replace when they changed the battery I'm guessing. All the vacuum bled out the screw hole. Put a new screw in and it worked like a champ. It is nice (and rare) when it is something easy on these cars.
 

LT4man

Well-known member
Joined
Jun 25, 2003
Messages
2,214
Location
Chicago
Corvette
96 Collectors Edition LT4
Thanks for the great information. Too bad you had to go through the longer repair process.

I will definitely file this in my memory under "Quick fix for cruise"!

SAVE THE :w
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
Thanks for the feed back

Wow a great write up thanks. When I come across something like this I print it and put it in a file called Corvette. It is surprising how many times you look at that file to jog your memory. Again thanks for posting the solution as well as the problem.:_rock
 
H

HD2HVETTE

Guest
The exact symptoms I have on my 93 Ruby. Thanks for the info!
 

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
Thanks John.

HD2HVETTE, Let us know if that's a fix for you please. I'm curious as to how prevalent that problem is.

thanks
 

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