Vacuum issue?
If I recall correctly when both my SAI valves weren't working because they wouldn't hold vacuum my cruise didn't either. I thought they were in the same vacuum circuit as the cruise control.
Follow your vacuum hoses from the intake plenum and test along the way. Test the little vacuum canister too. There's also a solenoid on the drivers side that is in the circuit too.
I used a cheapo handheld vacuum pump with a dial on it.
I have a 2004

 

Did you install LED brake lights?

 

Thank you! I couldn't find anything about this. My rave skills aren't too great yet.

The only line I see connects the actuator to a vacuum pump. I don't see anything going back to the manifold. If I understand correctly, the supply is from the little pump.

I did not, they're all halogen, and working just fine.

 

Has the cruise ever worked...or did it quit recently? It says it is detecting that the brake light is on...are you sure you don't have LED's in the brake lights? And when you say halogen...do you mean filament type bulbs?

​​​​​​​ Brian.

 

This rig is brand new to me, so I'm not sure how long it's been broken. I pulled all the bulbs out of the tails and replaced them last week, as a few were already burnt and I wanted a good baseline. They're all Sylvania LL filament bulbs now.

That's what I figured the Nanocom was saying but I wasn't sure. The brake/clutch switch light actuated properly when I pressed the brake. The tail lights themselves are operating as advertised.

 

Okay, just wanted to get a baseline.

Another question...what year are we working on? Does it have the brake lights in the bumper, also? Does it have a trailer electrical harness, sometimes they get corroded inside and cause issues. A small "back feed" (like a bulb socket corroded inside) can cause the cruise control to sense resistance.

I've read about folks having issues with their brake light switch, mounted on pedal. Could be working enough to activate brake lights (and your monitor device), but not well enough to unactivate (some sort of resistance inside switch?).

​​​​​​​It may still be something mechanical, too.

Brian.

 

Brian,

Thanks for your time. This is a 2000. There are turn signals and rear fogs in the bumper. There's no trailer harness hooked up. The plug behind the passenger side light looked pretty grimy - I wonder if that could cause an issue?

 

Could be. But, maybe we need to back up some. Does your main cruise control switch, on dash, light up when you push it in? l guess, you should follow through the wiring diagnostics that Overrover gave you, and see if that shows up anything.

Best4X4 has a write up on diagnosing the mechanical portion of the system, maybe he will check in soon...or PM him.

​​​​​​​ Brian.