1996 - 2500, Auto trans, Cummins engine

Can anyone give me some suggestions for testing sequence or items to be checked?

Here is the problem: When shifting to 4 H the 4WD light comes on, but is not engaged in 4 W mode. If I shift to 4 L the 4WD light is still on, and 4 W mode is fully engaged.

Thanks to alll in advance.

 

Question, should the drive shaft between the T Case and the front diff turn free when the 4WD is not engaged? If this is the case, my thinking is to jack front wheels off the ground and then see what turns while shifting to different positions, i.e., 2L, 4H and the 4L. Hoping this will show if the problem is T case or diff.

As to the Vac indicator switch on the T case where is approx location and how difficult is it to reach and last how is it actuated? Thanks again.

 

take a look at these links, also do a search here in 2nd gen, there's been some pretty good threads recently.

http://www.dodgeram.org/tech/repair/..._engagment.htm
http://www.4x4wire.com/dodge/tech/solid_axle_cad/

here's the scoop. best way to work on it is to put it up on 4 jack stands and crank it up and shift it, and allow CAD (vac thing) to operate and see what its doing.

you have several independent pieces, any of which can fail.

t-case. must engage and turn front drive shaft. also must flip the vac switch and send vac to CAD.

vac lines from engine to t-case to CAD. must work and not leak.

CAD must move shift fork from one side to the other and back again, based on vac on one line, then the other line. to do so the diaphram has to work, and the internal little shaft has to move back and forth and not be stuck (common).

axle halves must line up (bushing), and the coupler must slide over the inner half to lock it up.

and finally, when the shift fork slides all the way to the driver side and locks up, it depresses the switch on the end, which illuminates the cluster light.

since your light goes on and off properly, that tells me the vac and t-case sw, and CAD is working. But you said its not pulling, so the next biggest question is whether or not the front drive shaft is turning or not ?


edit - vac switch on t-case is up on the very top, front, in a difficult spot. follow the vac lines.

 

Thanks for some great information. I'll start the test and report what I find.

 

OK, thanks to the above information all test completed and problem ID'd.

Problem appears in the shift lever adjustment. When shifting to 2 WH, when the shift lever (in the cab) is detented in 2 WH the TCase is not engaged. When the shift lever is moved a 1/16 - 1/8 in toward neutral out of the detent I hear a little click and the T Case is engaged in 2 WH.

Thus my question: Where should I go for this adjustment? T Case linkage or is there a way to adjust the detent in the cab (on truck lever).

Thanks

 

Just to add to my post above, I looked at the linkage on the T Case and appears OK nothing loose. Ran out of time, so did not look for the lever position in relation to marks on T case.

Not sure why this shift would change. Is there any chance that the T case forks could have lost their pads? Would this alter the internal travel of the engagement mechanism(sp?)?

 

i don't know, as i've never opened up the t-case.
sounds logical that a missing pad could affect linkage position by 1/8 - 1/16.
also be aware that a broken snap ring is common, but i think (not sure), thats more of a grinding problem than an engagement problem.

i'd try to adjust the linkage a little. its the next easiest and least destructive step

 

I incorrectly described what I was doing above thus a reprint as do not know how to edit:

>>>>>>>>Problem appears in the shift lever adjustment. When shifting to 4 WH, from 2 WH, when the shift lever (in the cab) is detented in 4 WH the TCase is not engaged. When the shift lever is moved a 1/16 - 1/8 in toward neutral out of the detent I hear a little click and the T Case is engaged in 4 WH.

Now for what I did to hopefully correct the problem: The book shows great pictures of the alignment marks for the T case shift positions, but I found no markings on the T case for shift positions. Since all linkage seemed OK, I moved the rod at the trunion about 1/8 of an inch and this seems to have corrected the problem. Just seems odd that the vac indicator switch would actuate before detent in the T case, but I have not seen the inside of the T case. Maybe normal wear as was not like this when new, now about 205,000 miles.