71 Cruise Control Not Working BORG!!!

[John Morris #23947]

My newest land yacht is a 71 Sedan, garage kept since 80. 1st owner likely garaged it too. The only option not working is the cruise. I'm great at destroying things but not at trouble shooting. Where do I start on a 71?

[TJ Hopland]

Check vacuum lines.   There is a release valve on the brake pedal that could be not sealing.    A hand held pump / gauge works well for checking the release and the actuator.

Check electrical connectors.   The units usually ground through the mounting so making sure its not painted or rusted.

Check for any signs of life, fuse?

Check the engagement switch with an ohm meter.

If its the same as the later 70's system its a 2 step switch.  All the way in is the set.  Part way in is resume.  Thats why there is a notch out of the back around the button, if you only push it to the notch you are hitting the resume.   I threw a ton of parts at one of mine till I found out that if I just hold it to set for about 1/2 a second and then slowly release it over the next 1/2 a second it works fine.  I never had that issue with the lesser models that did not have the resume from the same era.   

[bcroe]

Those mechanical cruise controls tend to wear out the speedo cable parts.  At that age the grease probably is dried out anyway, so check it out.  Bruce Roe CLC # 14630

[bill henry]

no resume feature on those old cruisemasters

[TJ Hopland]

Did the resume come out in 72 or 3?   I owned my 73 for almost 10 years before I knew it was there.  Had other GM's from the era that did not have it.

[The Tassie Devil(le)]

I am sure thet they had the "Resume" feature.

My first vehicle with Cruise Control (Only ever had three) was my '72 Eldo Coupe, and I would set the Cruise at 100 MPH, then drop back to 35 MPH, and hit the "Resume", and enjoy the "Ride".

Bruce.

[TJ Hopland]

set the Cruise at 100 MPH, then drop back to 35 MPH, and hit the "Resume", and enjoy the "Ride".

Thats how I discovered the resume feature although I did not know it at the time.  I thought it was just screwed up.

[bill henry]

my 70 does not have resume nor did the spare system i scavenged out of a 71 sdv. however my 78 had a resume.

[TJ Hopland]

Must have been new for 72 then?      Just looked in the 73 manual and they make no mention of it being new or only on some models.  They identify the switch positions as Cruise (released), Engaged (partially depressed), and Trim (fully depressed).  Even though they dont call it resume they say when you partially depress the switch you will engage the system to resume where the transducer was previously set.  Maybe people were getting into trouble or did not understand this system (with no label) so thats why they eventually came up with the separate switches?


So hopefully someone will have an earlier manual to help John since it appears his system is different than the ones i have manuals for.

[bill henry]

the system is fully explained in the 70 shop manual so it should be in the 71 manual as well. It would be a lot of pages to scan and post.

["Cadillac Kid" Greg Surfas 15364]

John,
Now that everyone has settled the question of the "Resume" feature, a couple of questions.
1. When you drive does the speedometer work?
2. Have you checked all the vacuum lines as has been suggested?
3. Have you checked to see that the vacuum relief "switch" on the brake pedal arm is connected and is adjusted correctly?

After answering those questions what I have also frequently found is that the connectors from the engagement switch (on the turn signal stalk) to the transducer via the wiring harness (be careful it is a fragile, small gage wire flat blade connector) sometimes needs cleaning and re connecting.
Check the connections to the transducer and finally check the power to and the connections of the cruise control activation switch on the dash.
If in fact you end up needing a new transducer, they are still available.  Just bought one from Autozone.
Keep at it, I hope this ends up with less grief than your eldo flywheel/starter problem.
Greg

[TJ Hopland]

So other than not having the 2 step switch on the stalk the system is the same as the 72-77?  Im thinking it was mid 78 they went to the speed sensor in the dash and a control module?

Good to know they are still available.   Took one apart once, never did get it back together and working.  I do remember the grease being hard and that was when it was only about 10 years old. 

[bill henry]

in addition to the vacuum release on the brake pedal there is also a electrical switch to break the connection on the brake pedal. there were also 2 different transducers. I know this because in 1989 the dealer put the wrong one on a 76 i had at the tome.

[mgbeda]

I had two '76s with cruise that didn't work.  In both cases the problem was the electromagnet that holds the vacuum valve to the little speedometer inside the cruise transducer.  These coils, like many, degrade over time as their very thin insulation breaks down allowing an easier route for the electricity to pass through, but one that produces less magnetic field (electricity is basically lazy and always takes the easiest path).  Assuming that the transducer is well grounded (it is rubber mounted, but has a copper strap over one rubber bushing to ground it) you can test the coil by applying +12 volts to the "engage" terminal.  The magnet should snap home quickly and stay there.

If the coil does prove to be your problem it can be rebuilt by desoldering and unwinding the old coil wire and rewinding in with new wire.  This takes some time, but it worked for me.

-mB