My brother just bought a 2001 Dodge ram 24valve cummins. Today we went out to our farm and needed 4 wheel drive but to a shock we had nothing so we got on some better ground and locked it in to see what was up and the front driveshaft is turning but the wheels are not moving. The light in the dash comes on and everything seems to go fine but the front tires are not turning. Anybody have some suggestions about this one guy told me the electric hubs and another told be a the slave cyclinder so I am lost.

 

Vaccum operated CAD. (Central Axle Disconnect).

There'll be box on the front axle with 2 vaccum hoses coming from it, they might be red and black.

Make sure they are both hooked up and have vaccum.
One will have vaccum in 2 wheel drive, the other will have vaccum in 4 wheel drive.
(I forget which is which though)

If they both show vaccum when they should, you can pull the box off and make sure the fork moves.

Simple tests, others with more experience with the system will chime in I'm sure.
My 2002.5 doesn't have the CAD, so I'm just going off what I've heard and read here.


phox

 

well I looked at it and there is two wires that plug into a gold vaccum box I did not check for vaccum or anything. But I am taking it to get looked at tomorrow and was wondering what kind of problems am I looking at and cost I just bought this truck 2 days ago.

 

Had the same problem. You will have lines to the front axle and to the transmission (auto) or transfer case, not real sure. A single vacuum supply line runs up to the drivers side firewall area and ties in there. If the seal at the rear of the hood gets loose or if you have big hands and have been working in that area, you can disconnect the line from the firewall.
Hope this helps.

 

have a 2001 3500. four wheel didn't engage on one incident. dealer told me that those same vacuum lines, the ones mentioned at the top, one of the two came dislodged or yanked off from driving off road. don't know how true that is but is fixed now.

sometimes, the four wheel doesn't truely engage. i move the four wheel lever, light lights up and then i yank the lever one more time. now it moves one more inch. its locked in now. it wasn't before. four wheel trucks have personality...do you know any that don't.

 

ok can't really find any loose lines or anything but can't really see since it is dark a mechanic is gonna check it out tomorrow and see but I will let him know what to look for if it is not what you have mentioned before what else could it be? I am trying to make sure I know what to look for and what I am in for.



Well took the truck into the shop today and they said it was either the ring and pinion or the spider gears. I cannot hear any noise coming from that though so I was wondering is this right or do I need to go through all the vaccum lines?

 

if there isnt any grinding, ring and pinion shouldnt be it....

 

Wrong mechanic!!!

It's hard to diagnose from the keyboard, but I would keep that guy out of my pumpkins.
Sounds like your having the typical front collar not engaging.

Usually a vacuum leak, somtimes the vacuum motor/switch.

 

Well the mechanic said it was getting vacum, and the accumlator looked brand new, and it couldn't be the transfer case because the drive shaft was spining. He said it had to be something to do with the ring and pinion or the spider gears, or maybe there was something else inside that was causing the hubs not to kick over. I know, it sounds ridiculous to me to. So im suppost to take it back to them monday and there going to rip it apart and see whats wrong with it.

 

If the 4x4 light is coming on, that should mean the front end is engaged. I believe when the fork comes over to engage the front end. the fork hits a switch to tell the operator the axle is in.

 

Not knowing the 4WD worked before you bought the truck, could be a internal differential problem? but most of the time, like everyone else has said, it will be a vacuum problem. I had problems with the 99 I had and found the transfer case vacuum switch was either clogged up, frozen or stuck, I shot a load of WD40 into the switch and it started working. Be worth a try anyway. Also it is not hard to take the vacuum accuator apart and check the slider fork to be functional, you can slide it in and out by hand and see if it is locking into your drive shaft and axles before taking the differential apart........