wcbcruzer

I've noticed my truck will shift into 4wd low easily, but most of the time it won't shift into 4wd high. I'm going off the light in the dash, which should be an accurate way of determining when the front axle is connected or disconnected. What do you guys think might cause this?

06RAM2500

If it shifts fine and you don't have to fight it, I'd say you got a burnt out bulb.

Stamey

You gotta go through 4Hi to get to 4Lo. Are you saying the light doesn't come on unless you are in 4Lo?
If that's the case, look at the vacuum switch on the transfer case. On my 96, it actually was not the vacuum switch, it was the rubber boot/grommet that houses the 4 vacuum lines going to the transfer case. I got a new grommet from Dodge, pulled my vacuum lines from the old one, inserted into the new one, and the axle disconnect works properly again.

Chris

wcbcruzer

Yeah, that's what I'm talking about. When I put the t-case lever in 4-high, a lot of times it won't engage, but in 4-low it engages all the time. So you think it's the vacuum switch? That's the first thing that came to my mind as well. Do you know which vacuum lines do what on that switch?

Stamey

I don't remember which color does what, but there is vacuum supply, vacuum vent, engage and disenage, to the axle.
Soemone on here posted which color each one was, but I don't remember the exact post. Search for CAD on here and one of the threads will tell you the colors.

Chris

xtoyz17

I'd run to my truck if I wasn't in pajamas, but I coulda sworn my truck goes 4L - N - 2H - 4H.

Or did that change from 12v to 24v?

Regardless, it can't be a bulb and if I'm right on the shift pattern I'd say the lever is getting caught on something and won't go far enough. If I'm wrong on the shift pattern, then disregard everything I said

Stamey

2H - 4H - a little to the right, then N - 4L. That's an NP241 shift pattern.

Anyway, troubleshooting steps:
1. in 2H, engine running, do you have vacuum going to either side of the CAD on the axle? That vacuum would be to hold it in disengaged.
Yes: goto next step.
No: check to make sure you are getting vacuum to the T-case. Pull the connector from the switch on top and make sure something is sucking.
2. In 4H, engine running, do you have vacuum on the other CAD line from when you had it in 2H?
Yes: well what's the problem? JK.
Do you have a light on in dash?
No: put it in D and R then Park and see if the light comes on.
3. In 4L, with the engine running, do you have vacuum on the other line from 2H?
No: look at vacuum switch or connector grommet.

In my case, the connector grommet was old and loose, so I would get vacuum to disengage, but none to engage. The switch worked properly.

I could have put more step-by-step, but I'm lazy. You get the picture.

Chris

Tate

Are you sure about that? My 241DLD t-case goes 4H-2H-N-4L, all in a straight line.

You might want to confirm that the lever hasn't moved on the linkage (my 98 has a set screw on the lever arm to linkage). I forget what its like on the older trucks, but I think its similar. I'm guessing it moved on you and you're just stroked out on the lever, and not engaging 4H.

xtoyz17

As does mine, and I just snapped a photo. Unless the 12V trucks are different (I vaguely remember my 96 had a different lever and a funny looking shift pattern), my initial thoughts of the lever not being able to go far enough seems like it could be feasible with what Tate said.

wcbcruzer

Thanks for the help guys. Seems like a vacuum problem. After some more tests, it looks like it goes into 4-high about as much as 4-low, just not always, which these trucks are notorious for.

waldersha

Just to clarify, the shift pattern is different on my 96, just like Stamey said. All the way down is 2H, have to pull to the right to get into N or 4L.