I have a 1998 dodge ram with a cummins and my cruse will not ingage .the light indicates it is on but it will not go on cruse

hi clay can you tell me where about I would find the vacuum line you are talking about that goes to the cruise control module please and thank you in advance .....mike

It will go from the vacuum pump, which is behind the power steering pump on the driver's side of the engine up to a T at the top of the firewall and should run across the engine compartment to the passenger side fender area. There will be a round vacuum pod there that has to have vacuum or the cruise will not work.

If it's not a vaccume leak then check your brake lights or brake switch. I had one that had a blown bulb in the 3rd brake light on the back of the cab.

I have a 1998 Dodge Ram 2500 4x4 diesel that had the same problem. I found the solution when I was checking why I only had defrost going to my windshield and not coming out any of my vents. I traced my vacuum line and found a break in it. that also fixed my cruise control.