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Discussion Starter · #1 ·
This is on a 94 F150, but if it confuses you we will just call it a Bronco. The truck has sat for about 6 weeks, and the first time I drove it, yesterday, I was going down the highway with the cruise set on 77 mph. If I turned the blinker on to change lanes the cruise shut off. I could hit the resume button and it went right back to 77 MPH. This happened three times in a row, then it quit doing it, then it did it once again after I turned on the blinker maybe 10 times after that.
I'm not the best with electronic problems like this on the truck, so any advice you can give or areas to start looking is much appreciated.
 

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I would suggest that it is the little ground contact that is there just for cruise control. It is located on signal switch actuator under the steering wheel. It makes contact with the steering wheel to insure that the cruise control functions reliably. It is probably corroded or worn.

Probably the single most expensive part in the truck based on size. It is a spring loaded brass pin about 1" long by 1/16" in diameter. I bought one from Ford and it cost me $36.00.
 

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My understanding, at least 92-96 is that when you do the turn signal when using the cruise control it is supposed to disengage. That's at least what the for delearship said when i asked why mine does that as well. They said, "safety."

But hey, that can be a bunch of haa/haa.

What do you think steve?
 

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my 95 grand am does the same thing, doesn't always do it, but it does it enough to piss a person off. I was thinking it had to be some sort of wire grounding in the turn signal switch. you should pull your steering column apart and see if you can't find a chaffed wire in there and let me know.
 

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If you lose the brake light circuit to ground signal-eg:burn't out bulb(s),broken wire etc,the cruise can quit.When you turn you signal light on,you break the brake light circuit on that side to go to the turn signal circuit and the other brake light circuit maintains the signal.I suspect that you are getting a momentary open on the the brake light circuit(left and/or right side,depending on whether it happens on the use of the left,right or both sides)when you use the turn signals.Try replacing the bulb on the opposite side to the one that cancels the cruise(cheap to try).My next suspicion would be the multi-function switch getting a momentary open when the lever is moved causing the momentary loss of the brake light signal on both the left and right brake lights causing the cruise control to disenguage.
 

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Steve83 said:
Fred
Your steering wheel uses sliding contacts with spring-loaded pins. Mike's, because of the airbag, uses a clock spring.

Mike
You have a bad bulb, or a bad ground for the taillights.
Then I suggest that it is the spring contact. In either case the contact was originally put there just for the reason that the control was unreliable without it. I'd suggest that the guy at the dealership was FOS. That would be a stupid design and make highway cruise a PITA by purposly shutting off every time you signal a lane change.
 

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Ok, I just looked up the circuit in the 95 EVTM. The cruise control contacts (3) are independant of the multifunction switch. However, there is an indirect connection between the two functions that tells the speed control servo that the brake pedal has been depressed. That line hits the multifunction switch as well and it is possible that what Bronco1 is saying could cause a glitch on this line and make the SCS think the brake was depressed.

From looking at the circuits, I'd definately say the Ford guy was FOS.
 

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No, the blinkers should NOT cancel the cruise.

The circuit from the BOO that goes to the MFS & the cruise servo is parallel - a fault on the MFS side won't affect cruise, other than if it blows the fuse, which would totally shut down the cruise or if it shorts to hot all the time, which would always cancel the cruise. But a short to hot would also light up the brake lights & probably do some other weird stuff, so I think it would be more obvious. I still think it's just a fault in the taillight area, backfeeding power thru the brake circuit (LG/R IIRC) when the blinkers are used.
 

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Discussion Starter · #13 ·
Well I pulled the brake lights out and cleaned a little mud out of teh wiring and connections. Other than the dirt, everything looked new still with no corrosion. I put all new bulbs in just for the hell of it too, even though the others did all work. The sockets looked good too. Still clean and no corrosion on teh contacts in there.

As far as I know all the wiring along the frame is in good shape. I wired in a 7 pin plug about a year ago and everything will still in good shape then. I even loomed the new wired and the factory harness all together and taped it all up to keep the crap out. I'll see if it still has a problem now that I cleaned the mud out of the tail light plugs. Hopefully it won't because its going to be a bitch to find a short anywhere else
 

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Sorry Steve,but the use of the multi-function switch can cause the cruise to cut out.Have seen vehicles with 1 burn't out brake light bulb cause the cruise to cut out when the turn signals to the other side are activated.Also I have replaced multifunction switches for cruise control's that cut out when the turn signals are activated.
 

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but what I don't understand is how the cruise control doesn't always shut off with the turn signal. that to me kinda rules out the hole burnt out light thing.
 

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slaga said:
In My 89 Bronco, the bulb in the rear tail light was out . The left turn cancelled the cruise but it was the right tail light that was out. Replaced the tail light and cruise has worked perfectly ever since.

http://fullsizebronco.com/forum/showthread.php?t=60203&highlight=cruise
The fact that it is intermittent would lead me to believe that it is a bad ground issue rather than the light itself (as was my case).

kodiak said:
but what I don't understand is how the cruise control doesn't always shut off with the turn signal. that to me kinda rules out the hole burnt out light thing.
All I did was replace a light bulb which was burnt out and the cruise control started working like normal again. I am no electrical engineer nor do I play one on TV but that fixed my cruise control / turn signal problem.
 

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bronco1 said:
...use of the multi-function switch can cause the cruise to cut out.
Yes, we all know that. That's what this thread is about.
bronco1 said:
Have seen vehicles with 1 burn't out brake light bulb cause the cruise to cut out when the turn signals to the other side are activated.
Yeah, we've covered that, too.
bronco1 said:
Also I have replaced multifunction switches for cruise control's that cut out when the turn signals are activated.
So you're admitting that you replaced a $20-100 part when all it needed was a $0.50 bulb? :rolleyes: :wacko

FACT:
If everything is working correctly, the turn signals will NOT cancel the cruise. Turning on the hazards WILL. The MFS is NOT faulty.
 
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