I have a 96 1500 sport with the 318. I can not get it into 4wd. It will let me move the shifter like its working but there is no 4wd light and no 4wd. I took out the plug in the transfer case and the chain is still there and on the sprocket. Any other idea's before I pull it apart tomorrow? I do not get any grinding and other than this the truck drives fine.

Thanks!!
Alan

I'm not a 4x4 expert by any means but I think its might be the vacuum CAD not engaging. Somebody else might have other reasons why. BTW, welcome to the site!

I would have to agree. Check the vaccuum at the front axle CAD. It might be a vaccuum issue or the sleeve is not moving. Also is there any grind or jump when going to low. Someone on here also had the 4WD shifter linkage loosen up on them a while back.

You were moving while trying this on 4HI right????? 4LO, neutral, stopped.

You guys hit it right on the head. The vacuum lines are broken in more than a few places. Does it matter where I get vacuum from for these? They run up into an area that is really hard to work in to say the least! lol Two of the lines are burned off and I cant find the other ends and the other two are brittle so one goes to a connector that is hanging up in the transmission tunnel and the other is broken and hanging on by one side....

Thanks!!
Alan

Hi Alan,

I'm no 4WD pro either, but I happen to have a '96 RAM 1500 Sport with the 318 (5 speed) that also quit 4WD and I learned enough to tell you it matters a whole lot where you get vacuum from. Looking at the back of the right side of the front axle, you see the vacuum-driven shift motor and its diaphram housing. It has one electrical connection and two vacuum lines. Here's what's going on inside.

When vacuum is on the right side of the diaphram, it pulls a shifter fork to the right that moves a coupler with inner splines to the right. This mechanically connects a splined shaft coming from the front differential to the splined left end of the right front axle. If that coupler isn't in place, no power from the transfer case will be transmitted to the front wheels - no matter what. The electrical wire is connected to a switch inside the shift motor that's activated when the shift fork is in position to cause the coupler to connect the shafts. Bottom line is that when vacuum is on one side of the diaphram, you have engagement. When on the other, you don't.

Two flexible vacuum lines run from the shift motor on the back of the axle housing up and back to metal lines that lie along the inner side of the right frame rail to the level of the transmission. From there they go up and connect to flexible lines that connect to a vacuum switch on the transfer case. That vacuum switch applies vacuum to one line or the other according to whether the transfer case is engaged or not.

Not to discourage you, but I learned these parts one by one. When I first lost 4WD, I found a hole in the diaphram housing of the shift motor. So, it was a clear problem and I found a used one for replacement (of course bolts broke - got some out but now have a helicoil in one position). But 4WD still didn't work. So I looked further back and found the vacuum lines corroded and leaking - probably similar to what you found. So, replaced those. But 4WD still didn't work. I did have constant vacuum on one line and could go under the truck and connect it to one side or the other of the vacuum motor to engage or disengage. Since that was not an appealing situation for snow time in upstate NY, I bit the bullet and took it to the dealer for a new vacuum switch on the transfer case. Now for the good part - it all works now [8D].

I kinda wish I had taken another route - installing one of those after-market cable-operated systems to control the shift fork. That way you shift the transfer case and a lever in the cab connected to the cable. But it also gives you Hi and Lo in 2WD as well as 4WD, if that's worth anything. The cable kit isn't real cheap, but it's way cheaper than a shift motor, vacuum lines and vacuum switch.

If you go the cable route, be sure to strangle the vacuum supply to the vacuum switch on the transfer case to avoid a continuous vacuum leak.

Allen

Thanks for all the info guys. Its fixed! I reran the two lines to the front and repaired the line that goes up to the back of the head on the passenger side. Now I can go try and get stuck! lol I will probably have to replace the hose I patched at some point but I am done for today.

Thanks again for all the help I should have been on this board since I bought the truck last year!! Would have saved me allot of effort.

Alan

IN your earlier response you mention replacing the vacuum shift with a mechanical one. Can this be done on a 01 Ram 1500? If so where could I look to obtain all of the necessary parts to do it? I also live in the snow belt ( Minnesota ) and having a mechanical no-fail way on shifting to 4WD is pretty important to me.

Thanks.

If I remember right Tani1500 built one from scratch on his own... Would have to check pat posts to be certain. I have often given this thought as well as my truck engages rather slowly, I am sure due either to a small leak or a not very well lubed diaphram assembly.

http://store.summitracing.com/partde...4+4294925134+0

Outstanding!!

Thanks Chopper1. Exactly the info I wanted. Now to talk the wife into letting me spend the money.