My speedometer quit on me a few weeks ago and I wanted to get it fixed before the weekend and I didn't have time to fart around with it myself, so I brought it to a nearby mechanic I trust. (By the way, even if I had looked at it myself, I probably would have gotten totally frustrated because of my ineptitude of auto knowledge and ended up bringing it to him in another month anyway.)

So a short while ago he calls me and tells me my Cruise Contol Unit went bad and that's what is causing the speedo to not work. This makes complete sense to me because my cruise never worked properly from the first place, so I just never used it. Recently my speedo needle started to jump all over the place until it finally crapped out. It had also been squeeking (grinding) badly as of late.

So here is my question. Is anyone familiar with the "Cruise Control Unit"? Is there more than one unit that might have gone bad, and how difficult is it to change. The guy told me that I would have to special order it because none of his suppliers stock it. Thankfully, he's going to disconnect the cables so they don't bind up when I drive it home today and he's doing this at no charge. He's a real good guy!

I want to order the part and haven't even looked it up yet because I don't have a Vette parts mag with me here at work. I was just wondering if anyone knew the part in particular before I go searching and then likely end of taking a bad guess. :crazy:

One of the mechanics said it would be about 2 hours of labor because he would have to pull the master cylinder out of the way and a couple of other things. I was wondering if this is accurate, and if it isn't necessary to move the master cylinder, is it fairly easy to replace? My skills are limited, but with regular tools, I follow directions very well. I don't have too many specialized tools though.

Can anyone offer any suggestions? Thanks!!

 

On cars of your era, the speedo cable indeed went "through" the cruise control.

Once cable went from the tranny to the cruise vacuum module, then a second speedo cable went from the module to the speedo.

 

Well, having recently had to monkey with the one on my 78 I can tell you mine unbolted from the fender without touching the master cylinder. It is kinda cramped though. My car had the cruise unit bypassed with a cable running straight to the tranny. When I changed the steering column out I replaced the cable with 2 new ones. The cruise control does NOT work correctly and I'm thinking this is why it was bypassed. :banghead: I also developed excessive needle bounce in the speedo. So I opened the cruise unit up and cleaned/inspected it and put it back in the car.
I haven't had time to troubleshoot it any further as of yet, but at least the needle bounce calmed down.... :eek:

But on another note, here is a link to some detailed information on the workings of these units that might help.....or at least be of interest.

Good luck..... :steering:

Cruise Control
http://iotech.no/corvette/technical/corvette_cruise_control.htm


[Modified by c3vettelover, 3:37 PM 9/5/2003]

 

Thanks for your help!! I have a question though. If the mechanic said I need a new Cruise Control unit, do you think he's referring to the Transducer? That is the only part I can figure would be the right one. Please let me know. Thanks!

 

Have not changed one on a 1981 but on a 1979 it was not necessary to remove the master cylinder.
You may try your local Napa store as I have ordered them before with
overnight delivery. Have also ordered one from the local Parts Advance
store. If you order one, before installing it spin the shaft that the cable
connects to. It should spin with little resistance. When they fail, there
will be resistance when you spin the shaft. I have purchased several
transducers that were defective.

1981 transducer is different than the prior years as it has the resume
feature.

 

The transducer is the one that enjoys eating speedo cables.

Suffice to say, the easiest and BEST solution in my opinion is to just nix the transducer and run a cable straight from the speedo to the tranny. The cruise control system hardly EVER works, and when it does, it isn't all that hot anyways.

Like the others have said, if you want CC, you'll need to get a new transducer.

-Steve