Got into some mud today and when I went to put it into 4x4, the light came on, but it never engaged. I tried 4hi and 4lo with the same results. I tried it in neutral and in park, reversed a little bit and everything else I could think of and it still didn't work. Then the light wouldn't go off when I shifted back to 2wd. after restarting the truck, I got the light to switch right again, but it still won't actually engage the 4wd. I really need this to work and would really apreciate any help in figuring this out! Thanks in advance!

 

Any suggestions at all?

 

Bump!!!

 

Well, the only thing that I have found out from searching is that some people have got it to work by tapping the solenoid on the firewall and the motor on the back of the transfer case. This doesn't sound very helpfull, but with nothing else to do, I decided it can't hurt to try! So... this morning I gave both of them a good sound tapping, and then tried the 4wd and........ it works!!!!!! My question now is, how reliable is this going to be if it quit and I had to tap on things to make it work again? Is there any way of finding out which of the two tapped items was the problem and can I find a better fix than just waiting for it to stop working again and go to tapping?

 

You should have tapped one at a time then tired it, that would narrow it down. lol

 

I'm just a little surprised that there haven't been any more suggestions than just, "tap on it" !!!

 

Check this thread out and read the 4th post by JMC- the proper way to test the solenoids.

 

Torkum, I apreciate the help, but if there was supposed to be a link in your post, it didn't show. Could you try that again, please?

 

All you have to do is use the search bar, - it's what he did, for you.

Here, I'll do it this time -

https://www.f150online.com/forums/se...archid=4081360

You need to put a little effort into this as well.

 

Brew, you can't post search results like that - it doesn't work. All you get is this:

 

Ok, don't know whats going on but I'll try it like this

From JMC on test the hub actuator

Last week I replaced my cracked vacuum lines. I used a vacuum gauge to diagnose the problem. Do you have a vacuum pump with a gauge? You will also need a multimeter or a test light and a 10mm wrench or socket to remove the cover on the actuator motor. The first thing to check is for power to the solenoids. Behind the battery on the firewall. The one closest to the fender controls axle lock up and the other one unlock. The white and light blue striped wire should have power in run. If not check the fuse. Fuse #23 10amps in the cab. The PCM grounds the solenoids to control axle lockup and unlock. The red wire is the ground for the lockup solenoid. Either test it for continuity to ground with 4x4 engaged or connect the test light to the terminals on in the connector.
Do the same with the other connector except with the lever in 4hi. If this checks out you need to test for vacuum. I'll get back with a diagnostic procedure.

This is from JMC on testing the shift solenoids

There is a constant 12 to the solenoids. The GEM grounds the solenoid to activate it. Vacuum is channeled through the bottom nipple to the top nipple to activate the vacuum motor on the axle. When a solenoid is deactivated vacuum at the bottom is blocked and the top nipple is vented to air. This vents the vacuum motor so the other solenoid can pull the motor the other way.
The default setting ground applied to the disengage solenoid. You can test this with a continuity meter. Engage 4x4 and probe the red ground wire to the engage solenoid (closest solenoid to the fender). There should be continuity to ground. Then disengage 4x4 and probe the Gray w/Black stripe ground wire to the disengage solenoid ground wire ( closest solenoid to the engine). There should be continuity. If these circuits check out then test the solenoids. If they don't test OK the 4x4 indicator switch or the relay or the GEM may be defective.

Apply vacuum to the top nipples of the solenoids while the bottom one is blocked.
With with 4x4 disengaged test the engage solenoid. It should not hold vacuum. Then test the engage solenoid. It should be holding vacuum.
Then engage 4x4 and test the engage solenoid. It should not hold vacuum. Then test the engage solenoid. It should hold vacuum.

I would then test the blue and red lines to see if they hold vacuum. They may have a small leak.

 

Thank you, Torkum, for the helpfull post! If I have any more issues with this, I'll give that a try!

 

Well why the hell not, it use to ?? Let me try it again.....----

https://www.f150online.com/forums/se...archid=4085215

 

That worked. I must have screwed the other up somehow ?

 

No, it's session based. It works for YOU and ONLY you.

Click on this:

https://www.f150online.com/forums/se...archid=4085850

That's MY result when I search for all posts made by jbrew.......