Cruise Control Problems

[omega1940]

My cruise failed about 3-4 months ago and I haven't taken the time to fix it. I remember checking CAC a while back and someone mentioned being certain that the cruise switch on the brake pedal was not bent and was unable to open (or close ??) I checked that and didn't see a problem. Next I bought a new Cruise Servo from Mid-America and installed it yesterday and it still wouldn't work. I went to a local Chevy dealer and bought a new turn signal/cruise switch and plugged it into the wire coming out of the bottom of the steering wheel (after disconnecting the old one) and it still doesn't work.

I thought I found some earlier threads about a step by step checklist to see what's causing the problem, but I can't find it now.

Any great ideas floating around out there?

Thanks,

Mike

 

[Ken]

I couldn't find anything here on our site and I'm too lazy to type something up today, but I did find this for you Technical articles, How the cruise control works at another site.

Good luck.

 

[5pinball]

i think there is a transitor on 1 of your dash display bds that controls c control go to dsplay threads

 

[Magmotor]

I have the complete step by step voltage, resistance & vacumn test for the cruise control on a .pdf file. It's way to large (313K) to post on here so need a prvt e-addy if you would like.

 

[Bluesbrother]

Was cleaning the engine compartment on my 87 vert and found an unconnected hose down beneath the driver's side headlight. Got to looking around and found it was cut (chewed by a mouse?) and that it came from the servo to a round plastic tank about the size of a grapefruit. There was enough slack so that I connected it to the tank (found out later it is a vacuum tank). Took her out on the road and viola! The previously non-working cruise control works and has been working great ever since!:Roll :Roll :Roll Give it a try!:dance

 

[Ken]

Always a wise move - check all vacuum as well as electrical connections when troubleshooting an improperly working device. Sorry, I missed that.

_ken

 

[omega1940]

Cruise

I checked all of the vacuum connections that I could find, including the hoses coming from the eecs solenoid in the wheel well.

One thing I did notice is that there are two vacuum lines coming out of the back of the servo, one is a little larger than the other. Only the smaller of the two has vacuum when the engine is on. I wonder if both are supposed to have vacuum.

The little "T" connector/canister on the passenger side under the plenum is also in fine shape and is new.

I checked the brake switch for the cruise that disengages the cruise when the brake is applied. I had read somewhere that this bracket gets pushed back from years of use and eventually the cruise switch stays on even when the brake is depressed. Mine is fine.

I have replaced the servo.

I bought a new swith/turn signal assembly at my local chevy dealer and disconnected the existing switch at the bottom of the steering column and connected the new switch. Took it for a spin and sure enough, nothing happened.

I am thinking I have an electrical short or something and have no idea how to track that down. I'm going to take the car to an auto electric place nearby that should be able to find it in a heartbeat.

Any other thoughts?

Mike

 

[rocklyons]

Check servo

A frequent cause of cruise control failure is a torn diaphram on the servo.

Rock