[jelake]

Recently replaced my Transmission Valve Body as well as changed from 275/70/18 to 285/75/18 tires (33 to 34.5 dia). Tried turning on and set cruise control today, the light came on on the dash saying it was on but it wouldn't set. Any suggestions on why?

 

[busemans]

Maybe the brake switch went out? It should have Two circuits in it, one for cruise and one for the stop light

 

[jelake]

Maybe the brake switch went out? It should have Two circuits in it, one for cruise and one for the stop light

Was thinking about it some more last night- could it be that when I installed the Valve body that one of the two speed sensors on it got slightly depressed which is messing with the cruise control as a result? Wasn't much fun taking that thing down and putting the new one in on my own, performance with the new one has been on par, a few hard shifts but haven't written that off to the new valve body learning the shift patterns.

Where would the brake switch be located at? My hard copy manual is burried somewhere in the house as the kids walked off with it a few weeks back...

 

[busemans]

the brake switch should be by your feet. somewhere on the arm, or where the arm would push the tip of the button when you let go of the pedal

 

[dubyam]

Did you ensure the valve body you installed was a dead match for the one you removed? Could be slight differences in iterations, and your cruise control could be seeing a mismatch in speed sensed due to that. I know changing gear ratios in the diff will kill cruise control in these trucks.

Your idea about the speed sensor may also be valid. And Buseman's suggestion to check the switches (which will be two small block shaped switches near the top of the pedal arm) is good because killing off the easy to get to and test first is always wise. Adding a pic of what the switch looks like. Suze is similar to a small match box or such. As Busemans said, there will be two of them. Possibly different colored plug receptacles.