Differential Lock Shift Fork (1 Viewer)

[Hendrix834]

I've been battling my factory lockers for about as long as I've owned my 80 series and I've finally diagnosed the issue, but I need a little help from this point. All of the lockers function properly except for the rear diff lock. Just recently I learned that everything about the actuator is perfectly fine, so I thought maybe the fork shaft was bound up somehow. To test this, I pulled the fork cover and started to unbolt the 10mm bolt joining the shaft and the fork. I noticed there was a lot of resistance as I unbolted it and once I got it past the threads, the shaft pulled back towards the actuator. Luckily, with some help from a friend as he manned the diff lock switch, I was able to the line up the holes (after several tries) and put it back together. The only possible explanation now is that the fork must be bound up somehow. Before everyone starts in, I am aware of all the proper techniques to get the locker to engage (figure-8's, coasting, etc.). Even spinning the wheel up in the air won't engage it. I have no idea what the linkage looks like inside the differential, so I have no point of reference as to what could cause it to bind. Has anybody else experienced something like this?

 

[bloc]

The shaft out of the actuator is driven by a gear with a big spring on it. This allows the actuator motor to cycle fully even if the teeth/splines/pawls in the locker itself aren't aligned. The spring keeps pressure on the shaft, fork, and pawls so that it snaps into place once they are aligned.

The reason your 10mm head bolt had resistance was the actuator had cycled but the pawls weren't aligned (if not locked) OR disengaged (if locked) yet. The shaft and fork had spring tension on them, so when you loosened the bolt it bound up.

If you put both rear wheels in the air, axle on jack stands, and remove the inspection cover.. Cycle the locker and spin one rear wheel. You should see the fork start to push as soon as the actuator cycles, then snap across once the splines are lined up as both wheels turn. With no tension on the locked rear diff, if you disengage the locker actuator the fork should slide right back across.

If you are under it, inspection cover off, actuate locker, spin rear wheels, and it doesn't eventually snap in something is wrong. Could be twisted splines, gears not aligned properly with shaft in the actuator, etc.

I'll dig up some pics when I'm at a computer.

 

[Hendrix834]

The shaft out of the actuator is driven by a gear with a big spring on it. This allows the actuator motor to cycle fully even if the teeth/splines/pawls in the locker itself aren't aligned. The spring keeps pressure on the shaft, fork, and pawls so that it snaps into place once they are aligned.

The reason your 10mm head bolt had resistance was the actuator had cycled but the pawls weren't aligned (if not locked) OR disengaged (if locked) yet. The shaft and fork had spring tension on them, so when you loosened the bolt it bound up.

If you put both rear wheels in the air, axle on jack stands, and remove the inspection cover.. Cycle the locker and spin one rear wheel. You should see the fork start to push as soon as the actuator cycles, then snap across once the splines are lined up as both wheels turn. With no tension on the locked rear diff, if you disengage the locker actuator the fork should slide right back across.

If you are under it, inspection cover off, actuate locker, spin rear wheels, and it doesn't eventually snap in something is wrong. Could be twisted splines, gears not aligned properly with shaft in the actuator, etc.

I'll dig up some pics when I'm at a computer.

I knew about the wait spring pushing on the actuator rod. I don't think the issue is inside of the actuator because when I had my friend cycling the diff lock switch, the rod had no issue pushing all the way in and out. I'll do like you suggest, jacking the whole rear axle up and turning the wheels. I had only jacked up one rear wheel (since I don't have jack stands with me at school), but it's not allowed to rotate completely because of the CDL.

 

[bloc]

A way to do it with only one Jack would be to engage CDL, engage rear locker and let actuator cycle, then unplug the rear locker harness at the actuator. Disengage CDL. Transfer case in neutral, Jack up one rear tire, and this should leave the fork and spring loaded with the CDL disengaged so the drive line is free to spin and let locker splines align.

Another way to use one jack would be to disconnect the axle end of the rear driveshaft.

 

[Hendrix834]

Okay, last night I jacked up one rear wheel and went through the steps like you suggested. Rather quickly, it locked into place just like it was supposed to. I got it to go in and out a few times, but the dash light continued flashing. Everything was plugged back in and put together. I'm assuming now that the faulty part is the position sensor or maybe the wiring. Tonight I'm going to swap the position sensors (front and rear) to help diagnose the issue.

 

[ppc]

Take the connector of the sensor and short the pins and that will tell you if the wiring is OK. No need to pull a working sensor out of the front.