I have a 1990 dodge W250, and am having two problems that I haven't fixed yet.

One is, the gage lights will only come on if I turn the headlight switch all the way counterclockwise until it clicks, which should make the dome light come on, but rather it makes the gage lights come on. The dome light however, will not go off without pulling the fuse, no matter if the lights are on or not, door shut or open.

Second, the transfer case engages the drive shaft, but the front wheels are not being moved. It doesn't have lockable hubs on it, is there some kind of vacuum engagement, or are the locked full time? If so what lines/modules should I check, and where are they, and where do they go?

 

BTW, I could not find anything that appeared to be connected to the light switch, and I cannot figure out how one is supposed to get to the back of the switch to remove it, so I can check it with a voltmeter? Also, how does the **** remove?

 

To remove the headlight **** you have to reach up under the dash and feel on top of the switch, toward the front there is a little spring loaded detent that holds the shaft in the switch, however you may wish to disconnect the battery as removing the **** leaves the head lights on. Pull the **** out until the head light would normally come on, depress the little detent and pull the **** all the way out. Now, with out walking out and looking at my truck, I believe there is a round chrome piece behind the **** that looks like a piece of trim, which is actually a nut that holds the switch in place. You will need to remove the dash bezel to remove the switch. Now as to your hub situation, it sounds like you have automatic hubs up front. one way of checking if you have a hub problem would be to remove the covers off the hubs, they are normally held on by a couple of screws, with these removed you should be able to see the ends of the axle shafts, with the help of a couple of friends have one person on each side of the truck and one under it rotating the drive shaft with the transfer case in two wheel drive. see if either of the axle shafts is turning. If they are indeed turning, use a stick or something to try to pry up against the axle shaft, be careful not to get over zealous here, now try spinning the drive shaft again and see if there is resistance, if there is then more then likely you have one or possible both hubs that are bad. I do believe they make repair kits for the automatic hubs, or you can swap in a set of lock outs.

 

I am not sure on the 90s but my 89 has a 44-8FD axle that has an axle disconnect unit that locks the 2 axles together and replaces the auto hubs. It works by vacuum and is located on top of the front axle just below the drivers feet. I have had to replace the vacuum motor before. If it is there, that axle number will allow you to get detailed instructions concerning this set-up. Not all manuals cover this mechanism. If it is there clean the area good to prevent dirt and trash from entering the axle shaft. You can pull the unit by removing the splash shield, switch wire, and vacuum lines. Then remove the 4 bolts. You can test its operation with a vacuum pump while it is installed on the truck. Jack the left front tire off the ground in 4 wheel drive. Disconnect the vacuum lines and hook a vacuum pump to the drivers side port of the diaphragm. Jockey the tire a little bit and it should turn freely. Now apply vacuum to the passenger side port and jockey the tire the axle should lock-in and the tire will not turn. If you cannot go back and forth like this the diaphragm is shot. You can also insure you are getting vacuum to the diaphragm with a vacuum gauge.

 

Can I just put lockable hubs on it, and leave the vacuum operated unit alone?

Has anyone heard of my headlight switch problem? Any ideas on what is wrong or how to check it?

 

gonna seem like a stupid question but i know i my dodge the door will not hit the light switch on the inside of the doors, put the question is do they go off if you hold in the switch on the door and you mise well as pull the light switch its a easy thing to do to look at the resistor maybe its going bad shouldn't cost much to replace it

 

fixed the dome light problem by replacing the light switch, it also fixed the dash light problem. I'm still trying to figure out the 4x4 problem as the vacuum pump i rented doesn't work... I have 3 lines coming off the unit though, two on the motor, and one on the top, but i cannot tell where they're supposed to go, can someone tell me? the one on top appears to be plugged, what does it do? btw i broke the plug.

 

Hand held and operated vacuum pumps are cheap and effective. Buy one if you are going to work on vehicles. "I have 3 lines coming off the unit though, two on the motor, and one on the top," What unit? Please use specific names of things to help us visualize where on the truck you are talking about so we can better assist you. The first thing we need to do is identify the type of front axle on your truck. On the front axle tunnel between the spring and the gear housing on the drivers side is it smooth or do you have an axle disconnect unit with vacuum lines and wires attached?

 

sorry i was refering to the vacuum disconnect unit. It has two lines coming off the actuator motor (one to engage, and one to disengage) but there is also a line coming off the top of the housing. The one on the top of the housing was only about six inches long, and had some kind of plug in it that I broke. I'm thinking it's some kind of pressure release tube. Where should the actuator motor lines run to? They appear to head back toward the transfer case or transmission, but they are bundled with some other lines and I can't see where they connect, as some of them appear to be disconnected.

Basically I'm unsure where the vacuum lines are supposed to run to, I thought about just running a vacuum line to my manifold to engage the actuator motor and see if it works, but I imagine there is a specific vacuum source I should hook to so that vacuum will be applied to one side or the other depending on if 4wd is engaged or disengaged, am I correct?

 

I do not have a third vacuum line on mine. If you don't have a hand vacuum pump I guess you could use engine vacuum for the test but the truck would have to be running and that introduces an unacceptable amount of risk for my taste. Whatever the source of vacuum follow these instructions: Jack the left front tire off the ground in 4 wheel drive. Disconnect the vacuum lines and hook a vacuum pump to the drivers side port of the diaphragm. Jockey the tire a little bit and it should turn freely. Now apply vacuum to the passenger side port and jockey the tire the axle should lock-in and the tire will not turn freely. If you cannot go back and forth like this the diaphragm is probably shot. If this is the case follow these instructions: Clean the area good to prevent dirt and trash from entering the axle shaft. Pull the unit by removing the splash shield, switch wire, and vacuum lines. Then remove the 4 bolts and remove the unit by lifting it straight up. You will see a shaft that has 3 e-clips and a shifting fork on it. Remove an e-clip and the fork then remove the other 2 e-clips and the vacuum unit pulls out with the shaft. Assembly is the reverse of removal.
You can also insure you are getting vacuum to the diaphragm with a vacuum gauge. You should have vacuum on one of the hoses when in 4x4 and the other when in 2x4. If there is no vacuum these lines run up to a selector switch on top of the transfer case by your 4x4 shifter. The vacuum that feeds that the switch comes from a round accumulator ball on the drivers side of the tranny. It gets its vacuum from the engine. I have never heard of the switch being the problem but it is possible. If the vacuum motor is good and you have a switching vacuum being applied it is probably internal to the shifter fork inside the unit, this is also very unlikely. This is really not that hard or expensive to fix. I do not believe you can put locking hubs on this axle but even if you could you would have to lock that vacuum shifter fork in the 4x4 position. Just fix the problem. Being able to shift into 4x4 without leaving the cab is a real blessing especially when you are sitting in 6 to 9 inches of mud. LOL