F-450 Cruise Control and Turn signals

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There was a very similar post here a few months ago but I've forgotten what the solution was. Google alt.trucks.ford for cruise control and see if you get lucky.

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Reply to
Kevin Bottorff

Check the ground side of your turn signal lights. You have lost the ground, causing feedback through the brake circuit.

Reply to
Tyrone

My truck was behaving in a similar fashion. 3rd Brake light bulb was FUBAR. Changing the bulb fixed all!

Reply to
Peter Arnold

You need to check the ground to the brake lights and turn signals with a multimeter. What happens when the ground is lost is, the voltage applied to the turn signal can't go to ground. Being it has a common ground with the brake light filament, it returns to the brake switch through that filament. When the voltage is applied to that circuit, it is the same as you applying the brakes, thus closing the brake switch, thus disengaging the cruise control. Hope this helps.

Reply to
Tyrone

"JRNice" wrote: > Thusfar I have checked/cleaned the front grounds. I think the > wires afixed to the top of the core support near the > headlights are the ones. I checked the socket directly with > the battery. I got "0". I even added a 4 ga cable between the > negative post and the core suppport. > > still shows 1.5-1.6 volts on the cruise amp's light green > wire. > > I am re-checking the rear most gounds to the tilt bed. > > dang this is frustrating.

finished checking the grounds. I even disconnnected the cable for the old light bar just to be sure. I am still getting the same reading.

Any other suggestions? ......could this be a bad turn signal switch? I guess the only reason I suspect it is that the ignition has to be on before this voltage appears.

If this makes any sense, when I disconnected the rear lighting plug at the firewall the voltage went to 12. If I plug back in just one turn signal lead, the voltage drops to 2.14. .....basically the same happened when I disconnected the lead at the steering column.

EDIT: just replaced the turn signal switch......not it.......

I even borrowed the Rotunda Speed Control analyzer box from the Ford dealer. It showed trouble codes with the slip rings etc which is why I replaced the t/s switch. That problem fixed.....I moved on. still no resolution.

Reply to
JRNice

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