I am having somewhat of a similar issue with my 2001 Ram, although the low beam lights are real dim, the high beams are just as bright as what the low beams should be and the high beam indicator light is on when the low beams are on. Im figuring this would possibly be the hi/low beam selector switch, as i have already checked connections and grounds. Wondering if on this truck it is seperate from the multifunction switch or not.

 

figured out what happened - the guy i bought the truck from replaced the front clip along with the headlight assemblies - instead of putting the sport parts on he put the standard parts on - got the proper bulbs and works just fine - low beam 9004 high beam 9007

 

IME the OPs problem is nearly always due to bad connection between Front Control Module (FCM) and Intelligent Power Module (IPM or engine bay fuse box - call it what you want).
1. Disconnect battery neg
2. Remove FCM from front of IPM - 4 torx screws hold the FCM onto the IPM (FCM is the grey metal box mounted to the front of the engine bay fuse box).
3. Use contact cleaner and a stiff brush to clean up the pins on the FCM and reassemble - this MIGHT be enough if you're lucky, but often the problem will come back. If it does try these solutions -

1. When refitting the FCM, install 2 upper screws normally but loose, when you insert the 2 lower screws slide a washer BETWEEN the IPM and FCM so that when you tighten all 4 screws up, the FCM will have a slight tilt relative to the IPM.
2. Another way is to use long nose pliers to VERY GENTLY twist the blade pins of the FCM, and bend the small pins of the FCM - be very careful not to snap a pin off, or twist/bend too much so that the the FCM connector will not insert anymore - I'm talking about a couple of degrees of twist so not much at all.

I did option 1 on my 2001 Caravan 12 years ago and it's been fine ever since..