Simple cruise control Question

[BeagleRock]

Hi gang, I drove my 83 F-150 approximately 80 miles round trip at 75 mph Saturday to pick up a new sofa. TMI 😉  anyway I'm motoring along and pass a Dodge. While passing I actually use my turn signal! Well the cruise control deactivated!!!  Did it a couple of more times to verify that the signal light was causing the cruise to disengage.
 Obviously I have an electrical problem of some sort. Anyone else ever experience this in the past and if could you share the remedy.
 Thanks Randy Brown
Muskogee OK.

[Gary Lewis]

First, congrat's on getting it to 75!  Is it working well?

As for the cruise - I mean speed control - here's the wiring diagram: http://www.garysgaragemahal.com/speed-control2.html.  And the closest it gets to the turn signals is in the steering column - at the horn pad, which is right above the turn signal switch.  Hmmm.

Does your horn work both when the key is on as well as off?  I ask because a missing ground on the steering column can do that.  And it may also cause weird problems on the turn signal.

[BeagleRock]

Thanks Gary, actually hit 80 trying beat the storms. They had the angle on me lol 😁 I think I will dig into that because my turn signal cam is broken,i have to continually monitor the left arrow light on the left as hitting a small bump in the road will cause it to come on. It's like whatever holds the lever in the middle has alot of play in it and you also have to manually move the lever back to the middle after making a left turn. It should pop back to the middle or off position but you already know that 😄

[BeagleRock]

P.S. I found two more Vacuum leaks. One at the transmission modulator valve, the hose going to it was very spongy. The other I fixed at McDonald's on the turnpike, the hose off the vacuum tree to the cruise control slipped on and off like a straw in a soft drink cup. Luckily I had a utility knife and cut about an inch off the hose connected to the vacuum tree and boom! No more surging cruise!

[BeagleRock]

Not sure on the horn key position but it does work. Everything works except A/C. Even the cassette player 🎶

[Steve83]

This TSB is required reading for pre-'93 F-series:



The blinker turns the cruise off because of a fault in the brake lights, or their grounds, or in the trailer wiring.  Since the blinkers use the brake filaments, the signal backfeeds to the cruise module, making it think you're hitting the brake, so it cancels.

The turn signal droops & turns on by itself because the tiny plastic bosses on the cam are worn, or not molded correctly.  Dorman/HELP! cams are garbage.



It doesn't cancel because the long spring arms on each end of the cam break off (especially if you try to turn the signal on WHILE turning the wheel the other way).  The best fix for both is a MotorCraft turn/hazard switch assembly:

[Gary Lewis]

Steve - That's a good explanation.  That would do it.  

[baddog8it]

Thanks Steve for the TSB info!  I noticed that my cruise dropped out when I momentarily turned on my hazard flashers.  I assumed that I just bumped the key just enough to momentarily drop the cruise, but not enough to feel the engine hiccup.

One more thing to add to the to-do list.