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4WD not working?

24K views 61 replies 21 participants last post by  PMickey 
#1 ·
i was on a field road the other night and when i went to turn around i got stuck i put it into N and then put it into 4WD and i still was spinning so i punched it and got out so i was wondering if it was working and i was that stuck or i have a big problem.?
 
#2 ·
It might have been working. Do you have limited slip diff front and rear? If not 4x4 isnt that great with open diffs you get 1 wheel spinning in front and 1 in back.
 
#3 ·
I take it the back tires were still spinning, if so, some of the older transfer cases needed a rolling start to get into 4wd. I'm thinking the locking portion of t-case couldn't engage w/out a roll.
 
#4 ·
were the front tires throwing any mud or just the rear
 
#5 ·
that makes sense about the rolling start and i couldnt really tell if anything mud was rolling up or not because it was at night. i work in a shop so when i get a chance i will put it up on the lift and see what tires spin when its in 4WD. thanks for the replys though. im knew to dodge so i need some help haha
 
#6 ·
Just went through this with my truck. The vacuum CAD system on these RAMs is garbage, prone to failure and unreliable. For the front axle to be totally engaged with the transfer case it requires A) that the vacuum system operate the CAD motor properly, B) that the right front tire have some rotation so that the splined collar can slide over, and C) that there be no loss of vacuum anywhere in the system. There is about 20' of metal and rubber vacuum line snaking through the frame for this system. On older trucks there can be any number of rotted hoses or broken connections. There is also a vacuum switch on top of the transfer case that controls the system and it is also prone to failure.
I just replaced my vacuum system with a Track-Lok cable system and glad I did. It substitutes a cable for the vacuum junk so engagement is positive, no guessing if it is in actual 4WD, and a loss of engine vacuum won't cause you to lose 4WD. Since the system is now manual you can lock/unlock the axle regardless of the position of the transfer case shifter. This gives you 2WD low as well as letting you unlock the front axle in tight turning situations. The kit costs about $220, but is worth every penny considering what it replaces.
 
#8 ·
No, there are no locking hubs on the Dodges, haven't been for decades. These 2nd gen RAMs use a CAD system (Center Axle Disconnect) to engage the front axle with the transfer case output. When you shift the transfer case into 4WD that is only one part of the process. That merely locks output to the front driveshaft. A vacuum switch on top of the transfer case sends a vacuum signal to the CAD, which is supposed to shift a splined collar inside to lock the axle and allow power from the front driveshaft to go to both front wheels. If the vacuum system fails, you could still have power to the front driveshaft, but not to the front axle. Sometimes, the wheel has to rotate a little for that splined collar inside the CAD to move properly and lock the axle in. That's why on a system like this it is better to put it in 4WD before you need it because once you are stuck it may not engage properly if the right front wheel can not turn. And since it is dependent upon engine vacuum it may malfunction or disengage at any time if vacuum is lost. The Track-Lok cable system eliminates this problem entirely.
 
#10 ·
#11 ·
using a one pc front left shaft is a little better bang for the bucks. it gets rid of the cad and the slip collar and need for further rotation. Just grab the shifter and go. But if you have open diffs you are just pissing money away. 1st choice would be a locker in the rear... it would have keep you moving in the first place. 2nd would be a L/S up front or a selectable... i like the E-locker it is both a L/S and a locker a lot better for the front. 3rd would be some locking hubs, kits are bout a grand but you get way better bearings and can run in 2wd low range! when used with a locker it is golden.

good luck!

b


as a total side note, you are not stuck unless you need to be towed out! Don't spend money on this if you only use 4wd on wet grass!
 
#12 ·
I think you meant the right (passenger) side shaft as that's the side the CAD is on. The left (driver) side is already one piece. Who offers a one piece replacement shaft?
 
#13 ·
EMS off road does Miami.
 
#14 ·
Not according to their website: "There are no products to list in this category.":bawl:
 
#16 ·
Pretty much. The hardest thing is drilling the hole in the firewall for the cable to go through, but they give you a paper template to mark it out. You do need an 11/16" drill bit, though.
 
#17 ·
did you check your fluid level in the gearbox??

What about the cable, and the rod adjustment? is the rod there?
 
#19 ·
It could just be a vacuum hose off the CAD unit on the front axle. Look at the axle and you will see a little box deal on the pass. side. It should have 2 vacuum lines and a wire plugged into it. Check that the lines are intact and hooked up. If they are then you probably have a broken or disconnected line at the transfer case or the CAD engagement motor has gone bad.
 
#20 ·
it's funny about this CAD system. My 93 dak never had this vacuum lock system and "I think" my 99 durango doesn't. A friend that had a 94 dak had this vac box on his front axle. It's a visable box, around 4"x 5" iirc.
 
#22 ·
Dakotas and Durangos have independent suspension in the front, so no CAD on them like on a solid axle truck.
 
#21 ·
on the diesel models, i believe the shifter was cable, or rod driven. It is on mine i think.
 
#23 ·
Do you mean the connection to the T-Case? If so, yes that is a rod I think, but to the axle CAD it is vacuum.
 
#26 ·
so when i had it in the air i noticed my transfer is case is leaking so i got to fix that $225 and then have my 4WD looked at. hopefully its the activator or the fork. i will find out friday, let you know if i get it fixed
 
#27 ·
On my '99 1500 QC the 4WD lamp doesn't light up either. :bawl: The quick and dirty way to tell if your 4WD is engaging is to start rolling and turn the wheel all the way over. If it bucks and jerks and fights you, it's in 4WD. :WHT: Someone else suggested to me that its a good idea to try out your 4WD periodically (like whenever it rains) to make sure it'll work when you need it to. ;)
 
#29 ·
The quick and dirty way to tell if your 4WD is engaging is to start rolling and turn the wheel all the way over. If it bucks and jerks and fights you, it's in 4WD.
Not the best way to find out, You can break things in full lock.
 
#31 ·
It's way up on top, a little more toward the front. It has 4 vacuum lines going into a rubber plug on top of it. The switch is about 3 inches long and hex-shaped. If you got rid of the t-case vacuum lines make sure you cap off the one going to the engine or you'll have a vacuum leak.
 
#32 ·
Ok good to know, So the plug that the four connect to is where my hunting ends. I have 2 that go to the axle hard lines other 2 are broken (cracked) but also go to the plug. Being that the lines were broken and i threw them away, i opted to put no money in to the cad system. Thank you for telling me about the vac leak i would have forgotten all about that. Where would i look for the engine vac source for the cad or does any one have a diagram of the cad system:)
 
#33 ·
ok wait.. not to hijack the thread but where is this mystical place to get a one piece axle?? I hate my CAD. I got stuck on a beach (on a date) and in my driveway in the snow several times. I have replaced it once already. When it gets under stress it VIOLENTLY slams in and out of 4wd.
 
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