I have taken my truck in for this a few times and they cant find any reason for it. they cant find any log in the computer and no codes show up when they hook it up.


Every once in a while when I dont use the 4wd for a bit when I switch into the 4 wheel drive the service light comes on and the truck wont make the switch into 4WD. has anyone else had anything liek this on there truck...

 

Nope, it's always worked for me. I've even used 4-lo (once) and it went right in. There are only 2 things that could make it physically not engage... the front 'axle' central axle disconnect or the electronic module up at the t-case. There are lots of little electrical gremlins that could cause it though...

Is the electrical clip on your front differential completely plugged in? That thing kind of hangs out there, it's possible to damage that or the wiring - however, extremely unlikely.

 

mine was doing kind of the same thing intermittent 4wd engagement usually did not go in when it was cold, had to shut the truck off and try again usually the second or 3rd time it would go in. It would flash on the service 4wd light. It turned out to be the Drive Train Control Module located right where your passenger's feet are inside the cab.

 

Okay so I figured I would give you all a update..My ram is in for the secons time in 2 weeks for that service light. This is a total of 5 times in for this reason. Last week when it was in they found he 7 faults stored, It had 3 controllers in need of Updates and they inspected all of the wiring....Now you think with teh updates and all that they would have fixed it....well I got about 4 miles away from the dealership and bingo there was that pesky service light and and the 4wd would not engage! The Ram is back at the dealership and I am in a fancy Charger for the time being......glad I got that service plan!

 

I think I'd be asking them to install a new transfer case, if they cannot find the problem otherwise.