Hey everybody, The cruise control on my '72 Riv has not worked since I got her. Would any of you advise a process for diagnosis?
I can't help but wondering if anyone had the issues with early GM cruise control that I had.. Not to highjack this thread.. but I had cruise control on my 73 Riv back in the day. It would scare the heck out of me at times when I would go to signal and I think hit the re accelerate button by mistake and it would basicly just hit the throttle and launch the car at the wrong moment!!.. I don't know if it was a design flaw or the turn signal system needed to be replaced.. I remember disconnecting it, I can't remember if it was as simple as a fuse?? If it was a factory design flaw maby someone did the same on your 72?
Check to see if you have any vacuum leaks to start with. The brake switch breaks the vacuum to cancel the cruise. If vacuum circuit is good most likely the transducer is bad.
Ah, interesting info Peter and good to know. I don't think anybody has disconnected anything, at first glance everything seems plugged in and connected. How do I check for vacuum leaks Redman?
Well I'll tell you what a mechanic taught me about finding vacuum leaks. First visually inspect the connections. You may not see anything because sometimes the leaks are hard to find. Go drive the car for a little bit so it's warmed up. Park it and leave it running. Open the hood and with a can of starting fluid slowly spray all the vacuum lines and connections. If you hear the engine rpm go up a little when you are spraying something, you found your leak. In general though if you see/feel that any rubber vacuum lines are rock hard, they should be replaced. If they are not leaking they probably will soon.
Check all the above items but make sure you are operating it properly. Most people push the engage button ALL the way in . That is not the correct way . Try pushing the button 1/2 way in .
So I replaced all the components on my cruise system with the idea that i would get it going and use it. When it came time to hook the chain to the accelerator pedal, I decided that I wasn't going to place my life in the hands of a 50-year old cruise system. Now I just admire its handsome looks.
Ah yes, thank you very much for the tip. I did read the owners manual and noticed this weird way of engaging the system. Also that you have to be driving over a certain speed (30mph from memory.) I have tried engaging it a variety of ways but so far no success. I will try again before working on it though just to be sure.
90% of the time its the engage switch .To test all you need is another switch. Disconnect the original switch at the column and plug the test switch in and go for a drive .
Ah that's interesting to know. So when you say try another switch, do you mean just get a simply push button switch like this: https://uk.rs-online.com/web/p/push-button-switches/7346704/
check voltage signal at speedo cable drive junction on front fender. the lever switch turns it on and the brake pedal turns it off. solenoid valve controls the main vacuum to the carb linkage. theres also an air filter on that drive. make sure its free flowing. my olds toronado turned off hitting a bump. flashing the brake lights. changed engagement on THAT switch and all was good
No . The cruise control engagement switch / Turn Signal Lever. .It can be unplugged at the bottom of the column and the test switch installed without snaking it down the column for the test . Also OHM the brake light switch at both plug connections .
Oh, so you're saying that I should get hold of another leaver unit for testing? Like this: https://www.carid.com/qrp/cruise-control-switch-mpn-ch31611.html?singleid=1806571125&url=2220665
https://www.ebay.com/itm/1971-1976-...PSFirstClass!19050!US!-1&shqty=1&isGTR=1#shId Here's what yours should look like . I always had a extra one when I worked at the dealer for testing purposes . This is from CARS in NJ . Just a warning they have mixed reviews on many sites .
Ok thanks but I was just wondering if it was worth testing some other parts before spending $200 on a replacement stalk. If I were in the US then I guess I could just return it if it didn't fix the issue?
Ha, ha, ha... Good Luck! My 91 Mark VII cruise only works when it is below 70 degrees. Have chased that gremlin for four years. Mikey
I didn't read every response but here's everything I know about this system. The switch on the brake pedal has 2 switches inside. One switch is open (or off) when the pedal is up, it closes to turn the brake lights on. The other switch is closed (or on) when the pedal is up, this supplies 12 volts to the cruise control. When the brake pedal is pressed that switch opens and interrupts 12 volts to the cruise control which disengages it until it is re-engaged at the turn signal switch. There is also a vacuum purge valve on the brake pedal that is closed when the pedal is up. When the pedal is pressed the valve opens and it removes the vacuum from the cruise control which also dis-engages the system. When this valve leaks it can cause the cruise control to surge or not engage. When you press the brake the system dis-engages 2 ways, earlier systems didn't have the purge valve. With that said, you can trace the hose that goes to the valve a cap it off at the actuator under the hood for troubleshooting (you don't need it). You can test the turn signal lever switch with an ohm meter. Hope this helps.
Thanks very much for the information. I'll read back over everything here and consult the manual, then try and come up with a series of steps.
