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04' f150 4x4 troubleshooting

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    04' f150 4x4 troubleshooting

    4x4 stopped working a year or so ago. I researched the system and worked my way through potential problems. I replaced the solenoid on the fire wall that controls vaccuum. That didn't fix the problem so I moved on to the hub actuators. Both of them were bad so I replaced them and everything went back to working fine.

    You don't need 4x4 until you need it. And that is a fine time to find out it's no longer working.

    Before, the light was coming on but I had no 4x4. Now the light isn't even coming on. I checked the voltage coming into the solenoid and it measures exactly the same when switch is on 2H, 4H, and 4LO. That does not seem normal but I'm not 100%. I pulled the vac lines off the solenoid and I have vac on the bottom line coming in but not the top, which makes sense. I assume the solenoid allows vac through until 4x4 is engaged and then it shuts it off. When I hook just the bottom line up (the one pulling vac) to the solenoid, I get vac pulling through the solenoid regardless of 4x4 switch setting. That seems like a problem.

    So do you think the solenoid is bad? I would if i hadn't just replaced it a year ago. The original design from factory allowed water off the hood to compromise it but this one is a newer one with a rain cover. How could I test it? Apply 12 volts and see if I can blow through it? I guess I have kind of already done that since I know I am getting voltage coming in.

    My next thought would be the 4x4 switch but I'm not sure how to test it.

    I have tested all of the 4x4 associated fuses shown in the manual.

    #2
    I also unbolted the motor on the transfer case and I am getting no movement there when switch is engaged. It was working last time I checked it.

    It has to be the selector switch right?

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      #3
      have someone switch the switch to 4x4 high while you lightly tap on the motor with a hammer. the motor moving is what turns the light on

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        #4
        I have a 2003 FX4 that had a similar issue. Finally figured out that Ford put a nylon shift fork in the differential that engages the 4 wheel drive. They may have changed that though in the 2004 models.

        My mechanic told me that it was a broken shift fork. It's located inside the passenger side axle tube... It's the part that the actuator moves via the linkage arm... the shift fork throws a splined collar over the 2 piece passenger axle shaft thus locking the front differential to the ground.

        Not one of Ford's better ideas.

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          #5
          I pulled the selector switch last night and checked it. It has 4 prongs coming out of it. I checked continuity between every prong with the switch in all 3 positions. I never got continuity with any configuration but I'm not positive how the switch functions. I assume it is like every other switch and has power coming in and it closes circuits to send power back out. Therefore I would think the continuity test would work. I disassembled the switch to look for obvious problems. It has a small board in it which could be bad I guess. I did not see any physical signs of failure.

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            #6
            You tube has some good info

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              #7
              Yep i watched that video. And i think every other one on youtube that was relevant!

              Everything seemed to check out besides the switch so I figured out which prong of the incoming line was power and just made a jumper to connect it to one of the others. Boom, 4 HI kicked in immediately.

              I will provide some more information in case someone else comes across this thread in the future with the same problem. When I am making repairs, most of the info i find is on old forum threads.

              For 4x4 to work on these trucks you need two things to happen. You need to lose vacuum to the hub actuators and you need the transfer case motor to move into the correct position. With the truck running and in 2HI you can grab the front axles and spin them by hand. When you switch to 4x4 the hub actuators should engage and you can no longer spin them. No need to jack the vehicle up like everyone suggests. If both of those things check out then you vacuum system is working properly.

              Next is the transfer case motor. It is very easy to locate and access. There are 4 bolts that hold it on. Remove the bolts and slide the motor off but leave it plugged in electrically. Take a marker and draw a line across the moving portion of it so that you can tell if it moves. Manipulate the 4x4 switch and see if it changes position. If it moves, it is working. If it does not move, try tapping on the motor housing with a hammer. If that gets it going, the motor is probably on the way out. If the hammer does not get a reaction, the motor could be bad or the switch could be bad. Test to see if you have power coming in when the switch is engaged to narrow it down.

              VERY USEFUL INFO HERE that i never came across online but figured out along the way. If your 4x4 fails and leaves you in a bind, you can manually engage the system. Just pull the vac lines off of the hub actuators and then remove the transfer case motor and manually move the dial to the desired setting using pliers/vise grips etc. The housing under the transfer case motor is labeled with positions for 2 hi, 4 hi, and 4 lo.

              I was able to narrow my problem down to the switch because I was not getting action at the hubs (though I tested them and they were functioning properly) and I was getting no action at the transfer case motor. Now there is some other electronic elements to the system that I did not have to get into so I am not very aware of troubleshooting them. Such as the PCM, power control module.

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