2nd Gen Non-Engine/Transmission No 4WD Hub lock-up or light

[DWeik]

New transfer case less then a year ago, and new hubs last winter. Pull it up into 4WD high or low and no hub lock-up. Transfer case is fine. Any help would be greatly appreciated.

 

[rjrkihap]

Hi,



Since you said you replaced the hubs, I am assuming you don't have the central axel lock-up system (1st Generation). Everything therefore is mechanical. Don't rely on the 4x4 light in the dash. I’ve lost that before and still had a working 4x4 system. If you’re sure the transfer case is fine then you are transmitting power to the front axel (assuming that the front drive line is in tact). Unless the hubs are not engaging, then you should have 4x4. I would try engaging the T-Case on the street (pavement) and very slowly and gently turn in a circle. You will know immediately if the front end is engaging, as the truck will not want to turn without slipping the front tires (a bucking sensation).



Again, if you’re sure the T-case is fine, then the only other way not to have 4x4 is with broken hubs. Everything is mechanical.



If you do have the central axel disconnect, then your problem probably lies right here. I have heard of the system not engaging fully the slip color (not correct term). I don't have much knowledge here, sorry.



Good Luck



Ron



PS. I have had problems with the New Venture T-Cases and properly setting up the engaging forks. They can be finicky especially on a rebuild. You might check to see that they are actually fully engaging.

 

[vssman]

Welcome to the TDR!



I'm assuming you have a 2nd gen with the CAD (Center axle disconnect) equipped front axle. You have to see if you have vac going the the motor on the front axle. If not, follow the lines back to the transfer case and check the switch located on top of the transfer case. If that doesn't have vac, then go back toward the tee near the firewall on the driver's side, etc... If you have vac, is there oil in the lines? That tends to cause lots of problems with the vac motors. Finally I'd check the CAD to verify the fork slides the colloar on the axle stubs easily. Good luck and let us know how you do...

 

[DWeik]

Sorry Guys, the truck info did not appear?????? Yes, '98-2nd gen. 3500 Dually. 12 valve, auto. The hubs have a coax cable with 2 wires. these are also new with the hubs. Is there one motor or two? This is all new for me as I have been a GM owner for a long time. This Ram has it all over that want-a-be GM truck.

 

[jkalchik]

I'll bet that the wire you're talking about is actually for the ABS sensors.



Like vssman said, I'll bet you've got a CAD axle. Start with his post.

 

[Bob V]

This might help.

http://www.dodgeram.org/tech/repair/4X4/4x4_engagment.htm

 

[rjrkihap]

I'm a bit lost about the second generation having hubs. Could someone clarify this for me.



Thanks





Ron

 

[DWeik]

Thankyou for all the information. Looks like I have a Saterday morning project. From the repairs that have already been made, it really sounds like a vaacume issue. I will start there first at the switch and work forward. No switch function, no light, no 4WD?



Thanks Again

Dave

 

[PC12Driver]

I'm a bit lost about the second generation having hubs. Could someone clarify this for me.

This would be the hub. They're full-time (direct connection, no lock/unlock). All the second gen lock/unlock of the front axle was done with the CAD system (except the last of the 2002's that didn't have anything to unlock the front axle).

 

[vssman]

The light is activated by a plunger switch on the vac motor located om the axle. Look under the pass side door up toward the front axle. About 1/4 of the way in on the axle you'll see the vac motor & housing bolted to the front axle. I had a vac motor problem too and converted the cad to a cable operated Posi-Lok 4X4 unit.

 

[DWeik]

Would it be possible for the switch that turns the 4WD indicater light on to be damaged by excessive oil??? Pan gasket just replaced... That was fun.

 

[rjrkihap]

Thanks PC12, that makes sense.



Ron

 

[DWeik]

GOT IT !!

Started at the vacuum motor and worked backwards, cleaning and checking for vaacume as I went. I ended up the whole way back to the pump (left front engine). Here I found a small split in the line that was robbing about 75% of the vacuum. Nothing a side cutter and clamp didn't fix. Instant 4WD and dash light!

What does the vacuum have to do with the climate controls????They work better also.

Thanks for all your help :-laf

Dave

 

[PC12Driver]

All of the HVAC dampeners are pneumatically operated (by vacuum). The knob on the dash is just a rotary valve that controls what dampeners open and close.