Alright i have a 93 w 150 with a 318 and 46rh. My 4 wheel drive will not disengage it drives fine in 4h and 4l it just wont go into 2 wheel. I found that there is a vacuum motor that takes it in and out of 4 wheel drive. I checked and one of the vacuumn line inlets was rusted off and the other was almost off. Do i need a new engagement motor? not really sure what its called. how hard is it to put a new one in? Also my speedo and od do not work

 

Just because the front axle stays locked and therefore the 4x4 light stays on does not mean the truck is in 4 wheel drive. Some cleaning, 4 bolts, 2 vacuum lines, and a couple of c-clips and you have changed the vacuum motor. You can replace the vacuum motor or install a manual locking system.

A manual conversion system is here.
http://www.4x4posi-lok.com/app_dodge.html

Detailed info on replacement of the vacuum motor is here.
https://dodgeforum.com/forum/1st-gen...4-problem.html

Dorman offers a replacement vacuum motor. Part #600-202.
http://www.google.com/search?client=...7ae01271e8d1f8

Your speedo and odo are electronic and I have not seen anything on trouble shooting this system. Replacing the sending unit has fixed this for most people and that is the cheapest thing to try after you check all of the electrical connections..

 

Well i went to change the front u joint of the front drive shaft and when i turned it the front wheels turned. Then i looked at the actuator and the lines were rusted off. i will check if the lines are getting vacuum to see if the switch is good. And my indicator light is broken no lights come on at all because the electrical conection on the mount isnt hooked up, idk where it hooks into. I bought a vss for the transfer case but i think they gave me one for a 2nd gen truck

 

The electronic speedometer is considered a 2nd gen thing as it was introduced so late in the 1st gen cycle.

The 4x4 indicator light switch is on the other end of the vacuum motor and that is where the connector hooks up. It is actuated by the movement of the vacuum motor shaft.

The vacuum motor locks the front axles but this does not mean the truck is in 4x4. The transfer case must also engage the front driveshaft, differential, and axles for the truck to be in 4x4. The vacuum motor is actuated by a vacuum switch in the top of the transfer case when a 4x4 position is selected and the system is operating properly.

 

well when i have the truck in 2 wheel drive the front driveshaft still spins. idk where to start im not really a dodge guy at all. is it bad if i drive with the fronts hubs locked all the time

 

The front drive shaft turns in 2 wheel drive because the right front tire is engaged directly to it at all times and causes it to turn. This is normal. It is not being driven by the transfer case in 2 wheel drive unless you have major problems inside your t-case. If the front axles are locked constantly it will cause some tire scuff when going around corners and therefore cause a decrease in gas mileage and more wear and tear on the system.

You need to make a decision on how you want to repair the vacuum motor and fix that first. I have given you the choices. If you have specific questions I will be glad to answer them.

On a personal note:
I have something worn or broken in my t-case that will not allow the vacuum switch to be activated. I did not want to tear into the t-case. I removed the switch and plugged the t-case hole. I made a system that allows me to manually control the vacuum to the vacuum motor and therefore my front axle engagement. I now have a manual **** inside the truck that when turned engages and disengages my axles. I chose this method because it didn't cost me anything.

 

Alright correct me if im wrong, so if i put my truck in 4wd with out my vacuum lines hooked up i will have 3 wheels turning(back two and front left)? So the shift motor just locks the right wheel in for 4wd? I am going to check and see that i have vacuum going to the lines and if i do i will replace the shift motor. If i dont i will go with something like yours. Thanks, you have been ALOT of help

 

Without vacuum being applied to the shift motor your axles may be locked or unlocked. You have no way to tell unless you jack the front left wheel off the ground and check because your 4x4 indicator light doesn't work.

You should always have vacuum at one of the lines at the shift motor. Which line has vacuum is determined by the vacuum switch in the t-case. What you want to do is to see if the vacuum switches from one line to the other when you shift the t-case into 4x4. If this switching happens just replace the vacuum motor.

The shift motor moves a collar that locks the left outer axle to the left inner axle. Without the axles being locked no wheels up front will be driven in 4x4 due to the design of the differential carrier in the pumpkin.

 

Well id the left wheel is already locked to the drive shaft shouldn't it spin if the t case was in 4wd? Also do you know where the other end of the shift indicator light is supposed to be attached too? I traced it from the housing and it ends up by my battery not plugged in to anything

 

I am not sure what you are asking about the left wheel being locked to the drive shaft. The left wheel is constantly connected the the left outer axle. The right wheel, the right axle, the left inner axle, and the differential are constantly connected to the drive shaft. When the t-case is in 4x4 the right tire has resistance from the ground and the left inner axle can rotate freely if it is not locked to the left outer axle. Because the left inner axle can rotate freely, no torque/drive can be applied to the right tire.

One wire goes to the indicator lamp in the dash and the other should go to ground.