I just took my '96 2500 4x4 to my hunting property last week and when I pulled off the pavement I sank! With slick rear tires and + rear end I was'nt moving, so I shifted into 4 high and the 4wd light did not come on. The front hubs did'nt lock in and I was still spining. I have only had my ctd for 3 weeks and when I bought it I noticed the red vacuum line was unplugged on the tranny cross member right were it plugs on to the steel line so I hooked it back up. Anybody else had a prob with that? I tried the transfer case in 4h and 4L but no front end. The 4wd light would flash on when the case was going through neutral but thats it. Any Ideas? The transfer is fine cause 4L was creepn' so I thought maby the accuator? I have no Idea.

 

I'd say that you're probably right about the actuator. Mine did that when I first got it. Luckily??? I took it out in the yard when there was about a foot of snow on to try it. Needless to say it took quite a bit of spinning to get it back out and there was a little less grass the next spring.

It ended up being the vacuum control on the front axle that was bad. Replaced it and no more problem. I know there is about a 50-step procedure in the service manual for checking out the system. Maybe someone on the site can help you with where to start. Good luck!

 

Thanks, I guess the accuator has a diaphragm on it I could check with a vacuume pump & guage wonder how much vacuume the lines are supposed to have?

 

Mine had the same problem, a vacuume line under the hood on the driver side next to the fuel filter came unhooked, the line goes to the acuator on the front axle. you might try that.

 

Yea' I'm going to trace all my lines and make sure all are connected. I also might try to use my hand vacuume pump and make the acuator kick in and turn the 4wd light on. I'm pretty sure the indicator lamp switch is on the end of the acuator housing, I noticed that today when I was lubing the front end. I noticed an odd line hanging down next to the starter and shift linkage that had a small round connector with small pin holes around the inner circle, I have no Idea what it goes to as there is nothing that seems unplugged. I need a good service manual so I know where every thing goes. Does the vacuume pump for the brakes run all the vacuume for the truck?

 

Typical problem for these trucks

plain and simply said, i had the same issue happen with me, so i decided to posi lock it and forget about it It is the best thing you can do for your truck. NOw if you are bent on keepin the OEM vac system id look here. Get under your T case and make sure that the vaccum lines are not covered up in oil, or unplugged for that matter. If that isnt the problem, check the switch at the top of the transfer case. It is a four way plug that only goes in one way, it might have caused ur 4wd to not work.

if neither of those are the problem then you move to your vaccum actuator. It has two prongs connected to the OEM actuator. Pull that plug, in 2wd you should have one sucking in air and the other one should be inactive, in 4wd, the inverse happens and the collar gets pushed by the other line to engage your 4wd.

common problems here are rusty collars, not enough oil to allow it to work, or you have a leak in the vac system somewhere. Make sure you also check to make sure that every vaccum line is plugged up or connected. this will make your system not work if they are not. If you find a loose one, use a little zip tie and clamp them to where they go, problems will be reduced that way...

If you decide to posilock it, just get the kit from 4wheel parts, i spent 200 bucks and change for it on sale and it has more than paid for itself already...

Have a look see, and a pic of the final install.

https://www.dieseltruckresource.com/...ight=Posi+Lock



HOpe this helps

Rick

 

Thanks Rick, that looks like what I need. What did you do with your old vacuume lines?

 

I didnt do anything with them..

what I did was hang up the lines with a zip tie up and out of the way. They have not affected anything else, i know that my cruise control dont work due to battery acid corrosion.

With this system you dont have to worry bout ur 4wd anymore. You can disconnect the lines all the way to the T case and plug them up, but i chose not to, (dont know why tho)

Rick

 

I appreciate all your help. I have a 4wheel parts less than 5miles from my house so I'll stop in next week.

 

If you don't plug the lines you have a vacuum leak. One line or the other at the actuator is always sucking.
A vacuum leak will suck in any contaminates that find their way into the hose right into your crankcase.

 

Yea' I planned on plugging them, I still want to know what that connector is by my shift linkage. It does'nt have vacuume on it maby I should take a picture of it and see if anyone can I.D. it. It looks about like a 12 or 14 guage wire with a round center female (rubber conn.) about the size of an old barrel fuse with maby 5 or 6 smaller pin holes around it. The whole connector is about the same size as a vacuume connector. Any ideas?

 

That hose sounds like the vent line for the front differential but it's supposed to be connected to the fender under the airbox. Perhaps it fell down.

 

I just need to trace every thing and make sure all is connected. As for the unidentified conn. it is on the left side (driver) so I'm not sure Infidel. Thnks for all the help though.