I'm having a problem with my '08 Ram 1500 4x4, 5.7L.
I think this started a few months back, I was on a short trip & my overhead console was out/dark, no display. Hit all the buttons, still nothing. About 2 start-ups later it started working again. A couple hours later I tried to use the cruise & it hasn't worked since. The light in the dash wouldn't even come on.
Took it to the dealer & they told me my left front speed sensor was bad. I replaced the sensor (myself), & same problem.

I disconnected the negative battery cable for a while, same thing.
Today I took the plastic off the column, took the kick panel off & took the airbag out & there's nothing obviously wrong in the clockspring area, etc.

I even jacked the rear of my truck up, attempted to set the cruise & tried to test the purple, purple/orange & purple/brown wires with a test light. These are in the white plug that plugs into the clockspring on the underside of the column. (I grounded the test light to a factory ground & probed all 3 wires mentioned -separately- while hitting the "ON" button w/the truck going over 35mph jacked up). The test light never lit up....which leads me to believe (if I'm testing it right) my problem lies between the connector & out to the front of the truck in the fuse block, or that area?

I'm just out of ideas... & everything else but the cruise works, all the bulbs work, overhead console works fine, no check engine light, no airbag light, horn works fine...... HELP....lol

 

One other thing to check is the brake light switch. Plug loose on mine caused cruise not to work, even though brake lights worked.

 

OK I will take a look at that & report back- thanks

 

Otherwise, I'd guess a trouble code has to be reset by scanner.

 

Get the codes read would be your first step. Be careful around the air bag wiring, static electricity or jumping the wrong wire can set it off. Disconnect ground at battery and wait two minutes before removing air bag.