4x4 won't disengage?

[jballard81]

Evening!
94 ranger 4.0 auto hubs, auto transmission, all stock (afaik).
Got the bright idea to test the 4x4 dash button.

4x4 light did not come on, but I felt the front engage. So I pressed the button again and then rolled it backwards to disengage. It didn't disengage. I can feel it binding in reverse too if I turn the wheel.

Put both axles on jack stands and shift the trans to 1. Slowly let off the brakes and check, yup, both front tires are spinning.
Tried pressing the 4x4 dash button again and then put it into reverse, let it run for a count of 10, then back into 1 to see if it would disengage. Front tires still spinning.

Did some reading, tech section to the rescue!
Sounds like the tc shift motor needs some attention.

Pulled the shift motor off and it definitely looks like the tc is pointing to 2H

Is it possible the crappy auto hubs got stuck in 4x4? Or does there need to be some kind of resistance when backing up (so not on jack stands...) to disengage it?

The little sensor that came out looks to have a good chunk of metal dust on it.

Going to have to get a pry bar on the tc fill plug as I couldn't get it to budge with a half inch ratchet and some choice words.

 

[jballard81]

Additionally, the tech section article shows the shift motor 'cap' innards. How does it come apart? I really don't want to break it by just prying on it...

 

[jballard81]

I'm guessing this truck has seen very little 4x4 usage. Upon inspection of the gear, I was expecting to find the bushing blown apart like the article shows..

It's pristine. Not smooshed or beat up at all.

 

[jballard81]

While i was there and this is still a new vehicle to me, i went ahead and drained and refilled the transfer case. It was definitely needed.

 

[pjtoledo]

the shaft pointed at 2h does not do the actual shifting. it puts pressure on a spring that in turn puts pressure on
the shifting cam that actually moves the shift forks.
the shift forks won't move until the gears line up, that's why you back up to relieve tension & align the gears.

there is a collar that slides and couples the rear output shaft with the gear/sprocket that drives the chain for the front output.
sounds like that collar is stuck.

maybe you could induce some vibration/rattling to entice that coupler to move.
try having 3 wheels on the ground & one jacked up.
grab that one and rock it back 'n forth to induce some drivetrain shocks. you may get lucky, at the very least you'll
probably scare your neighbors away.

going to 4L engages that coupler and the planetary gears for reduction.

 

[jballard81]

Interesting, thank you for the detailed response regarding how the internals of the TC work. That's super helpful!

Any chance you have experience with the shift motor? Specifically regarding the 'innards' of the cap and how to get at them? I guess its possible mine was not meant to be serviced?

 

[pjtoledo]

I did tear into a motor once, it was more in the line of destructive analysis.
since I'm a bit fuzzy on those details I'll let another expert help you out.
other guys have cleaned the contacts inside them, so it can be done.

 

[jballard81]

Well, found an old picture of the cap disassembled and figured out how to do so.

I imagine at some point in the last 30yrs the plastic surround that holds the interior cap in place was somewhat flexible. That's no longer the case and I ended up breaking about 2/3 of it in order to release the interior cap.

Broke the oring inside as well but don't really see the importance of it. Cleaned off some black grease from the contact pins as well as the circuit print board.
Then added just a little dielectric grease and closed it back up. Added a touch of epoxy to make sure it doesn't come apart

Probably should have tested the motor itself before spending the time on this part. But will do that and then assuming it's ok, reinstall.

Won't help me with my current issue of 4x4 not disengaging, but I can add it to the checked off list.

**Tested the motor on 12V and it's still good**

 

[jballard81]

Reinstalled the shift motor and while still on jack stands wanted to see if it was still stuck in 4x4.

It's back in 2H! front DS and wheels no longer moving. My assumption is that the various testing i did the other day (when first put on jack stands) must of gotten the gears to shift however i must have turned it off before trying to change gears to R or D one last time. Or maybe the fresh fluid change helped, the stuff that came out was pretty gross. Either way, good news and i refrained from trying to test the 4x4 button again.

I'm going to run through the tech article on testing the 4x4 module before attempting it again

As always, thanks for the input and help!