2nd Gen Non-Engine/Transmission 4x4 problem

[Cowboy Medic]

It is snowing here pretty good today and I was using the 4 wheel drive. All of a sudden a I hear a small thunk and the 4x4 light goes out. Sure enough I am no longer in 4 wheel drive. So I shift the transfer case back to 2wheel and the light comes back on. Still no engagement as far as I can tell. Put it back in 4wheel hi and the 4x4 light goes out again. Is this a vacuum problem? It seems like the transfer case is fine as it shifts smoothly and I can still drive just fine, I just don't have the front wheels actually being powered and the 4x4 light seems to be backwards as it comes on in 2 hi and goes off in 4 hi. Anyone have this happen to them? What did you do to fix it?



Thanks



Jon

 

[McLaughlin]

OK thats wierd. If the light had just gone out and the 4x4 disconnected I'd suggest you look at the vacuum system. My daughter's 96 had a problem with her 4x4 the other day and is looks as if the snow had worked the vacuum connector loose on the passengers side of the front axle. When I checked it, it one of the sides of the plug was real loose. I pulled it off and pushed it back on pretty good and the 4x4 started working again(I can't specificaly say if that fixed the problem or not because I also jiggled all the connections on the tranfer case(took the boot off to get to them) before checking the 4x4 function. From what you are seeing, I'd suspect the switch on the transfer case may be bad; however, I check out the vacuum part first. You might also want to see if your cruise control and heater vent switch is moving the air from defrost to the other postions as a check. In the 96s and 97s both those systems also relied on vacuum to work correctly. If they both work OK then you probably have a bigger vacuum problem.

 

[Cowboy Medic]

My heater and cruise all work good. I too was thinking something either in the cad, or on the vacuum switch that the transfer case has. I will try crawling under and seeing if a line got knocked loose or something.

 

[McLaughlin]

To check the vacuum connection on the axle, you can just reach in over the passenger tire and fiddle with it(don't have to lay on the cold cold ground). Thats what I did and I'm not that small a guy. Can't really see the connections that well though.

 

[Eco Rednek]

Mine quit working below freezing, I replaced the CAD system with a . 4x4 posilock cable system Works real good, no more problems... . Oo. Anyway, when I pulled the old CAD system, it was frozen solid, could not move it with my hands. put it on the woodburning stove, when it thawed, about a tablespoon of water poured out of the VAC actuator.



The way the 4wd light works is, when the vac pushes the fork over to connect the axle it pushes the rod into an electrical switch.

If you have vac to the CAD, Its not too big of a deal to pull the CAD off and see if it is contaminated with water. If I had known, that would have fixed my problem and saved me 200. 00 but I m happy I replaced it because the VAC system is plagued with issues.

 

[MarkMiller]

4x4 posilock conversion here and couldn't be happier. I can manuever my gooseneck in 2wd low and don't fear the vacuum gremlins anymore.

 

[Cowboy Medic]

I crawled under and checked all the vacuum lines and the connections. Everything seemed to be good, but I got in the truck afterwards and everything was working correctly again, so it must have been one of them that was loose just a bit. Going to keep and eye on it and if it dies it again I think I will just replace all the lines. I've got 158,000 miles on the truck and have never had to mess with them before, so it may be it is just time.



Thanks for the replies guys. I looked into the posilock? system but just can't see spending that kind of money. I have always had good luck with the 4wheel drive in this truck and would just prefer to keep using it as I have been. I do have a 2 wheel lo kit from Pacbrake and I really like that as well.



I do think I will go buy myself a good set of tire chains. When I had a 2 wheel drive truck I always carried a set and was wishing the last two days I had some.

 

[PC12Driver]

Funny, mine did the same thing. It made absolutely no sence to me at the time so I just chalked it up to being a fluke and pretty much forgot about it.



It happened to me when I was slowing for a stop on dry pavement last fall. I heard a slight crunch and saw that my 4wd light was on (I didn't touch the t-case shifter). When I got to work I pulled the t-case in to 4 hi and the light went out. Back to 2 hi and the light came back on. The next morning everything worked normally. Never had it happen since.

 

[nps]

Sounds like the vacuum switch on the tcase is going flaky engaging the CAD. PC12 - do you have a 2 lo kit also?

 

[SnoKing]

Mine quit working below freezing, I replaced the CAD system with a . 4x4 posilock cable system Works real good, no more problems... . Oo. Anyway, when I pulled the old CAD system, it was frozen solid, could not move it with my hands. put it on the woodburning stove, when it thawed, about a tablespoon of water poured out of the VAC actuator.



The way the 4wd light works is, when the vac pushes the fork over to connect the axle it pushes the rod into an electrical switch.

If you have vac to the CAD, Its not too big of a deal to pull the CAD off and see if it is contaminated with water. If I had known, that would have fixed my problem and saved me 200. 00 but I m happy I replaced it because the VAC system is plagued with issues.

OK, tell me about shifting on the fly with the Posilock. Can you pull the transfer case into 4wheel high and then pull the control for CAD engagement at highway speed? Or is it the reverse. I would like 2 LO at times, and might go with the Posilock if I do not loose shifting on the fly! SNOKING

 

[nps]

OK, tell me about shifting on the fly with the Posilock. Can you pull the transfer case into 4wheel high and then pull the control for CAD engagement at highway speed? Or is it the reverse. I would like 2 LO at times, and might go with the Posilock if I do not loose shifting on the fly! SNOKING

As long as you engage the Tcase first to spin up the meatball, then hit the posilock, the operation is the same as the factory vacuum motor. The only caution would be to pull it in firmly but gently to let things come together rather than mashing it in.



I've thought about attaching a PTO cable to the vacuum actuator rod to get 2 low. The posilock replaces all those parts, but a PTO cable where the vacuum motor goes would be the same principle.

 

[PC12Driver]

PC12 - do you have a 2 lo kit also?

Yep, I've got the Pacbrake setup also. That's the first thing I checked when things flaked out. It didn't have any stray voltage and the switch was working properly. And it would work when I flipped the switch, except the functionality was backwards (since the axle was locked in 2-hi, the switch would unlock it). So it appeared to work. But it fixed itself before I could really tear into it and see what the problem was.

 

[cromptrj]

Im glad to hear that someone had good luck with the posilok i tried it and my collar still would not stay on the intermediate axle so i replaced it and it still slipped well now it wont work at all so im ordering the dyna trac hub kit .

 

[JustinLee]

A problem of my own; I just had the cad apart today trying to get it to work. Just so I understand this properly the actuator moves the rod (arrow), moving the fork, sliding the "ring?" connecting the axle shafts and four wheel drive is in. That is my understanding, please correct me if I am wrong. So if I have this correct, my rod does not move at all and there is no snow in CA to blame. It should by hand shouldn't it?



thanx

justin

 

[Eco Rednek]

Justin,



You ve got it right, mine would not move when frozen, but moved freely when warm,



I called dodge dealer to see how much it would cost to replace vac motor, it was more expensive than the posilock cable.

 

[nps]

Yep, I've got the Pacbrake setup also.

Hummmmm - only two reports of this behavior and both rigs have 2 lo kit from Pacbrake. Sounds suspiciously suspicious.

 

[cromptrj]

Ya i have checked the adjustment on the pull of the shift fork and every thing it keeps pushing the collar off messing up the splines on the intermediate shaft

 

[Cowboy Medic]

It happened again today and so I bypassed the pac brake 2lo kit and voila everything works fine. I am suspicious that maybe the switch is being activated even though the switch in the cab is off. When the weather is a little warmer I will be checking that. for now it will just remain bypassed because I have never really used it when the weather is bad because most of our trailers with where we park them I leave the 4x4 engaged because there is so much snow and ice.