Cruise Control suddenly stopped working
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
Cruise Control suddenly stopped working
1985 4+3 Vette
I've had Cruise Control working since I bought this car, don't use it often but I'm kinda obsessive about everything working correctly...
It worked a few weeks ago, right before I took the clutch master cylinder off to swap the part out. That's right next to the Cruise Control, so I'm wondering if I might have bumped something. I checked the vacuum lines and they look good, the big electrical connector for the servo is plugged in, the fuse is good, what else could have happened? Visually nothing looks out of place.
I've had Cruise Control working since I bought this car, don't use it often but I'm kinda obsessive about everything working correctly...
It worked a few weeks ago, right before I took the clutch master cylinder off to swap the part out. That's right next to the Cruise Control, so I'm wondering if I might have bumped something. I checked the vacuum lines and they look good, the big electrical connector for the servo is plugged in, the fuse is good, what else could have happened? Visually nothing looks out of place.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
You could have also bumped the switch out of adjustment under the dash. After fighting with mine for weeks (the attempts were in years but I only really messed with it for a few weeks.) I got pretty familiar with it. Lift up on the brake and clutch pedals and see if it will engage then. If it does you just need to adjust the electric kick out switches under the dash. The other thing you can do is key on run car off and flick the cruise from off to standby. You should get the click. If not then lift up on the pedals and retry. If you get the click adjust the switches as well. Same thing minus the drive.
Edit: the click to which I'm referring is the servo under the hood clicking.
Edit: the click to which I'm referring is the servo under the hood clicking.
Last edited by 84 4+3; Dec 18, 2017 at 11:43 PM.
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
I didn’t realize there were parts to it under the dash-that’s almost certainly what happened. I tried to be careful under there, but it’s tight and I was mostly focused on the clutch stuff.
I found the clip btw. When I went to put an aftermarket cotter pin in, I noticed it stuck on a wire up under the dash and managed to pull it out. I’ve got fat fingers so all these detail jobs that require you to reach up under something usually give me trouble.
Might be after the holiday before I’m able to dive in under the dash, but I will get this fixed. I’m a bit OCD even though I don’t really use the cruise that often (DD doesn’t even have it), I want it to work!
Thank you all for the help. I really appreciate it.
I found the clip btw. When I went to put an aftermarket cotter pin in, I noticed it stuck on a wire up under the dash and managed to pull it out. I’ve got fat fingers so all these detail jobs that require you to reach up under something usually give me trouble.
Might be after the holiday before I’m able to dive in under the dash, but I will get this fixed. I’m a bit OCD even though I don’t really use the cruise that often (DD doesn’t even have it), I want it to work!
Thank you all for the help. I really appreciate it.
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
had the same thing happen when I changed out a brake booster, bumped the brake pedal switch for the cruise control, had to go back under dash and readjust.
Safety Car
Joined: May 2001
Posts: 4,759
Likes: 1,647
From: Fairfax Virginia
Hello Again,
In my 1988 Coupe the Cruise had been working fine until one day I tried turning it "on" and it would not operate.
It was one of the vacuum hoses that went to the control unit. It looked "fine" from the top but others kept hearing it. (I have a serious hearing loss). So one day I had my son help me and he found it right away by following the noise from the vacuum leak.
Once removed the hose would literally crumble in your fingers and was a real pain to replace it all but well worth it. The brake/disconnect switch was a "bear" to do for me as well.
"Replace anything made of rubber that is original" is the way I do it. If you think replacing the vacuum lines on a C4 is bad then you should try replacing the vacuum lines on my 1968 C3 Big Block Convertible. There must be 75' or more of vacuum lines in the early C3's, fortunately they have colored stripes on them to keep track of where they go.
I wish you all a Very Merry Christmas and an awesome New Year driving your Corvettes!
In my 1988 Coupe the Cruise had been working fine until one day I tried turning it "on" and it would not operate.
It was one of the vacuum hoses that went to the control unit. It looked "fine" from the top but others kept hearing it. (I have a serious hearing loss). So one day I had my son help me and he found it right away by following the noise from the vacuum leak.
Once removed the hose would literally crumble in your fingers and was a real pain to replace it all but well worth it. The brake/disconnect switch was a "bear" to do for me as well.
"Replace anything made of rubber that is original" is the way I do it. If you think replacing the vacuum lines on a C4 is bad then you should try replacing the vacuum lines on my 1968 C3 Big Block Convertible. There must be 75' or more of vacuum lines in the early C3's, fortunately they have colored stripes on them to keep track of where they go.
I wish you all a Very Merry Christmas and an awesome New Year driving your Corvettes!
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
My vacuum lines actually look pretty good, they don't feel like they are a problem at all. The rubber feels very soft and not brittle at all.
Thanks for the tip! I tend to agree on rubber stuff as it doesn't always age terribly well. I'm almost certain it's the pedal switch after talking to people on here, but with the holidays I doubt I'll have time to mess with it for a while. Like I said I barely use it, but it bugs me it doesn't work.
Thanks for the tip! I tend to agree on rubber stuff as it doesn't always age terribly well. I'm almost certain it's the pedal switch after talking to people on here, but with the holidays I doubt I'll have time to mess with it for a while. Like I said I barely use it, but it bugs me it doesn't work.
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Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
Mine drove me crazy as well. Didn't work since we bought it in 08. Finally fixed it this spring. Mine was a very special circumstance though. I had a Darlington transistor that blew open on the ipc.
Everything on mine tested good. It even clicked it just wouldn't close and take vacuum. That transistor being open caused the cruise control module on the ipc to think the brakes were always on. It caused no problems other than no cruise. Wanna talk about going nuts after I actually started searching lol. You'll get it. It's more than likely one of the switches got moved. It's the easiest to to check too. Keep us posted.
Everything on mine tested good. It even clicked it just wouldn't close and take vacuum. That transistor being open caused the cruise control module on the ipc to think the brakes were always on. It caused no problems other than no cruise. Wanna talk about going nuts after I actually started searching lol. You'll get it. It's more than likely one of the switches got moved. It's the easiest to to check too. Keep us posted.
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 165
From: Nashville TN
2017 C4 of Year Finalist
Mine drove me crazy as well. Didn't work since we bought it in 08. Finally fixed it this spring. Mine was a very special circumstance though. I had a Darlington transistor that blew open on the ipc.
Everything on mine tested good. It even clicked it just wouldn't close and take vacuum. That transistor being open caused the cruise control module on the ipc to think the brakes were always on. It caused no problems other than no cruise. Wanna talk about going nuts after I actually started searching lol. You'll get it. It's more than likely one of the switches got moved. It's the easiest to to check too. Keep us posted.
Everything on mine tested good. It even clicked it just wouldn't close and take vacuum. That transistor being open caused the cruise control module on the ipc to think the brakes were always on. It caused no problems other than no cruise. Wanna talk about going nuts after I actually started searching lol. You'll get it. It's more than likely one of the switches got moved. It's the easiest to to check too. Keep us posted.
