ok guys give me an idea what to look for. I was at my cabin the last 3 days, and it rained most of the time. Got ready to leave and was backing up the hill, somewhat steep, to hitch up the ATV trailer, started spinning so I stopped and pulled the lever back to 4HI. Nadda. OK, pulled forward and tried again, still no engagement of front wheels. Tried 4LO too. Nadda. When moving forward in 4LO I swear I could hear the front diff gears doing their little hum that they do. I would imagine (and hope) there is something stupid going on here. Had something similar happen on an old Dakota, turned out to be a disconected vacuum line on some sort of black ball on the inside of the frame rail. Have not had a chance to crawl under the truck since I got home tonite. BTW, it is a 1997 1500.

 

I would say look at the vacuum lines. My cousin had a new truck back in 94 I think it was, and the 4wd wouldn't work because the vacuum line had came off.

 

I'd check the vacuum lines both at the axle and at the transfer case. They've probably come off at one of the spots. Happened to me last week when a bunch of ice built up on my skid plate and then melted off.

 

Yep, vacuum lines are the first culprit to suspect. Mine came undone near the transfer case. Probably due to brush or snow pulling at the connector while I was driving. I have since ditched the vacuum modulator because I don't like losing my 4WD capability during the winter.

 

well all vacuum lines are connected that i can get to. I cannot reach or see where they come together on top of the bell housing and below the distributor. Any suggestions? I would really like to finish this tonite!

 

It might be the motor that ingages the front axel. If it is not used regulary, it will dry up and not work when u need it. Thats why i use mine atleast once a month. But anyways that could have died, or the fork thats attached to that motor may have slipped and not be ingaging the front end. If its not this it is the vacuum lines like everyone else said. Have u worked on the frontend at all lately?

 

this might be out of the ballpark but when i put mine in 4 wheel..either lo or high... it takes about 10 feet for it to kick in..sometimes less .. it never engages right when i shift into any kind of 4 .. have you tested it on a no slip surface..not a road but dry grass or gravel? test it again and mess aroudn with it...i thought mine was junked too when it didnt kick in when needed but after 2 trips to the stealership... the mechs told me its common with electrical locking diffs... sometimes it happnes sometimes it dont...

 

thought of that too shott, hell I drove it around the block in both LO and HI on the pavement, nothing. I think I will price a servo motor (I believe that is what dodgeitri was referring to in his post) in the morning and if not too bad will hang one on to see if that works. If not maybe I can get some conversation out of a Tech at the dealership and maybe not.

 

I would definitely check the vacuum lines and the vacuum pump. Chrysler products are notorious for issues with this. I have an '89 Wrangler that was always iffy on 4WD. Finally got tired of no 4WD especially when it was cold (diapharm in the vacuum pump was froze up) so I removed the old pump and put a Posi Lok on. Works great! Cable acutated and it works as soon as I pull the lever.

 

In an earlier post, I stated that I had ditched my Vacuum System for the front axle. What I did was get rid of the Vacuum Diaphragm (sp?) that operates the fork in the front axle that engages/disengages the 4WD system.

There is a "system" sold for around $199 called Posi-Lok. Basically, it consists of a Adjustable Remote Throttle type plunger unit that mounts under the dash and an actuator assembly that replaces the Vacuum Diaphragm on the axle.

4WD engagement isn't automatic anymore with this system, but it has several benefits. 1. You can use the 4LOW portion of the transfer case without engaging the front axle. Useful when you need some low speed torque but not 4WD, such as pulling a boat up the boat ramp and out of the water. 2. When you engage the system, you can usually feel the front axle engage which sort of takes the guess work out of 4wheelin'. "I wonder if the 4WD is working?" I've asked myself that question a few times. Not anymore. You'll know it.

Just my 2 cents worth.