Need help with this issue. when I turn on the Cruise the dash indicator comes on, then when I try to set the speed, the indicator turns off and the cruise in not on. Any one have this issue. I drive a 2002 ram with the 5.9L

 

it's most likely the switch on the brake pedal.Mine was doing the samething,I changed that switch and it has worked ever since,I think there like 10-20 dollars at autozone

 

maybe a speed sensor ??

 

Common issue with 5.9 gassers that start to get a little age on them.

Look underneath the battery for a loose, deteriorated or leaking vacuum supply hose. Battery acid drips on this hose and destroys it.
The Cruise Control (and the HVAC for that matter) uses the vacuum reservoir so if the hose develops a leak, the system will fail. The vacuum reservoir is mounted in the right cowl plenum area, under the cowl plenum cover/grille panel. The reservoir contains a one-way check valve to trap engine vacuum in the reservoir.
The vacuum reservoir cannot be repaired and must be replaced if it craps out.


There is a TSB out on this, at least for the 2nd Gen 5.2 & 5.9L engines, number 08-22-97. This bulletin involves installing a gasket between the battery tray and the Battery Temperature Sensor (BTS) to prevent battery acid from dripping onto the speed control servo vacuum hose.

 

Also a common issue with the ABS and some issues with Diablo tuners on later year trucks

 

ok. bringing all this back up. mine is doin the same exact thing. but i figured one thing out. not sure if its it er not. but i was testing the brake switch out. when i have it plugged in and on the pedal as normal. that is when the symptom occurs. i turn the cruise on n itll stay on for a few seconds n go out. when i have it plugged in and off the pedal. the cruise light will stay on, n not turn off till i turn it off. but the cruise still doesnt work. i can activate the servo with my scan tool. and the servo activates. i can here it click. and i tested my cruise control switches. and they r good. i also have power up to them. i found a test for the switches on napafix. common rpoblem with em i guess is for a broken wire at clock spring or a bad clock spring itsself. but i elimiated that with power up to the switches. only thing i can really think of is either a vaccuum leak at the servo or my brake switch. i really dont no truthfully. just was searchin and seen this. any ideas or help is GREATLY appreciated.
THANKS!!