Engine/Transmission (1998.5 - 2002) 4X4 Gurus need your help!

[craftybigdog]

Hey guys I have a 2001 Dodge 2500 with the cummins.



Here is my problem. The 4X4 light will not come on when shifted into 4 wheel drive. Also the cruise control light will come on but will not engadge. I was wondering does the cruise vacume under the driverside battery tray control the 4X4 also. Because I was just under there the other day wiring up the snow plow lights. What is your take on this and where should I start?

Thank you for your help!

 

[bschmidt]

I would start with looking for a possible vacuum leak

 

[darkhorse]

My 4wd indicator light won't light either, but my cruise works. Yes the vacuum does run the axle disconnect system on the front axle.

 

[Allnew2Me]

Cruise control does not operate the CAD, but cruise is indeed operated by vacuum as well as the CAD. The CAD (center axle disconnect) is controlled by a vacuum switch in the transfer case. If you reach up on top you will feel it, there are four lines in a rubber push-on connector. You can check it to see if it is okay but if you were working under the dirvers battery you may have pulled or moved a line. The vacuum pump is engine driven and piggy-backs with the power steering pump. Look for the vacuum lines there and follow them to make sure all are connected. Also, if your heater controls don't work that would also indicate a loss of vacuum.

 

[TWilkening]

I believe that sometime in the 01 MY cruise control went from being vaccuum controlled to ECM controlled. First thing would be to see if 4wd light comes on when you put the key in run position, at least in darkehorse's case.