4 Wheel Drive
 

Im needing help my 4 wheel drive system isnt working. I replaced the motor on the front axle and the switch in the transfer case. Can anyone tell me what else i can check before i take it to the dealer

thanks guys
john

First, try manually excercising the linkage at the motor with the front end in the air to make sure the slide coupling isn't jammed. You may have to spin the front tire a little to make the splines line up. Next, try engaging 4x4 with the truck on the ground and running in park/neutral. Check for appropriate voltage at the motor. If there is no signal, work your way backwards to the switch checking for voltage along the way. Does the shifter engage properly? Move the truck back and forth slowly while shifting into 4x4hi. There should be a definite "clunk" into gear with significant throw on the shifter lever. If everything above is working and the light on the dash is on but you still don't have 4x4, then there is probably something fowled up in the transfer case. The light on the dash comes on when a limit switch on the slide coupling in the front axle is in the correct position. So if the light is on but you're still not engaged, that would indicate the "hubs" are locked, but the front drive shaft is not being powered by the xfer case. Hope this helps.

Make sure that you have vacuum going to/from the switch. If they vacuum is good, the switch is good, and the motor is good, then the problem has to be with the coupler.

When you replaced the motor, did you properly align it's forks with the coupler on the axle shaft? If that is installed wrong, it will never be able to engage the coupler.

The engagement of the coupler is all vaccum. There is NO electric motor in that assembly.

IM pretty sure i hae the fork right. It slide back into place as far as i could tell. The light isnt coming on which i know means the motor isnt moving over. can anyone tell me how i can check the vaccum to see if there is any at the motor or what else i can do

john

buy a $14 vacuum gauge and measure it? disconnect the vacuum line from the vacuum motor, plug the line on the gauge, start the engine, engage 4wd, and read the gage.

this gauge is also useful for all sorts of other diagnostic tests, too ;)

clarification
 

You're right, there is no electric motor. The slide coupling is actuated by a solenoid controlled vacuum "motor". The layman's term is just "motor" for short. I don't mean to be nit-picky, but the verbage needed clarification for anyone who might not know the difference.

When I had a problem with mine the light wasn't comming on either.

I found a piece of vacuum line and tested the motor from manifold vacuum to make sure it worked.

Sure enough after some testing I found a cracked metal line running along the frame rail.Then I used the same rubber line to fix the cracked one.

Re: clarification
 

???? I was the one who corrected you, as you stated "Check for appropriate voltage at the motor". This would lead anyone to believe that this is an electric motor, not a vacuum motor.

also remeber you will only have vacuum on one of the 2 lines at a time !!!!!!!!!!!!!!!!!! one line will have vaccum when the transfer case ball switch is in the 2 wheel position and the other will have vacuum when the transfer case switch is pushed into the 4 wheel drive position! Yes he said voltage ,busted! Thats a chevy thing not a ram thing!

coop 96 where did you hook the hose into on the manifold i may try that

john

vacuum
 

Here's a web site that might help? Then again might not? Dodges are about half way down. Good luck
http://www.4x4posi-lok.com/pdfs/troubleshootguide.pdf

Thanks for the link. One quick question, does both of the vaccum line that go up inbetween the firewall and the engine hook into something. I was looking to see if everything was hookup and i seen one line was and one line was haning but it looked as if it was capped.

john

I used a "T" to put it inline with the vacuum line going into the pass. side of the intake manifold just below the vacuum port for the PCV.