F-450 Cruise Control and Turn signals

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.

The OTHER Kevin in San Diego <skiddz "AT" adelphia "DOT" net> wrote in news: snipped-for-privacy@4ax.com:

just quick, it sounds like the brake switch may be bleeding through some. KB

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

I just pulled the switch earlier today. I pulled the connector off the switch. There was 12+ volts on the light green(wire) side and 1.64 volts on the other (light green and red). I assume this means that since the switch was eliminated, the source of the leak is elsewhere. I looked at the schematic and it showed the light green and red going to the emergency flasher. But it doesnt in "real life" ...so I was unable to trace back. (Funny, the spare dash I have has it as the schematic.) My F-450 doesnt look like it has an anti-lock computer as shown. I’m still looking. I actually thought maybe it was a short in the turn signal switch This is driving me nuts .....and I have a 500+ mile trip coming up......... Thanks ..... J. R.

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

Just to clarify, do you mean each individual ground on each light? ......or somewhere else? If the grounds were bad, wouldn’t the brake lights/ turnsignals not work? I will check tomorrow when I have some help. Thanks! J. R.

Just to clarify, do you mean each individual ground on each light? ......or somewhere else? If the grounds were bad, wouldn’t the brake lights/ turnsignals not work? I will check tomorrow when I have some help. Thanks! J. R.[/quote:5a3d3bfe7a]

Tried wiggling wires today....grounds look tight on rear end (it’s a rollback) noticed that when turn on the light switch (parking lights) the voltage jumps up to over 2.2 volts. When the signals and parklights are on together the voltage jumps to 3.5+.

THis voltage only shows up with the ignition on Any more ideas?

Thanks J. R.

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.

Sounds logical and simple enough. IF only I could find the grounds at the body! I checked through the socket and got .20 ohms. (Assuming I reading the meter correctly. I found a loose/questionable ground in the rear for the "wrecker" cable. Although I have removed the light bar the cable still runs from the rear to the front and services a few electrical devices. Still no luck yet......but I appreciate the guidance. I also noticed tht when I turned on the "wreckers" work lights the voltage on the light green wire spiked up over 3.5 volts. not sure why.

Not being an electical expert, I’m not real sure which is the gound inside the plug. It uses 3357 bulbs.

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.

"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.