Diff lock actuator details • by: glen gustafson
The rear actuator on my ’94 had apparently been completely filled with water for some time.
When I opened the housing, there was a sucking sound and water ran out on the ground. It had also gotten back into the electric motor housing. The housing “O” ring appeared to be holding a good seal.
There was rust and corrosion everywhere; the worm gear was worst off, as it was partially eaten by rust. The motor’s magnets had come unglued from the housing and came out clinging to the armature. The little ballbearing at the base of the armature was frozen with rust.
The braided copper pigtails to the motor brushes were corroded where they were crimped to the circuit board. (I soldered them).
The bleeder inlet and bi-directional spring were choked with rust.
That said, I did get the actuator back together so that it works. Took a lot of fiddling and cleaning, though. Glued the magnets back into the motor with JB Weld (epoxy).
Make a note of the position of the large gear and the actuator rod *BEFORE* you remove the parts from the housing!
Also, the actuator calls for the orange FIPG goop from Toyota. I tried getting it directly from Three-bond, but they just sent me to the dealership.
You also need some loktite (242 I think) for the small bolt that connects the actuator rod to the difflock inside the housing (through the little cover).
There are 3 contacts that slide against a plate on the back side of the large gear. I believe they tell the ECU when the motor has reached the end position. The motor runs immediately to the selected position, and the bi-directional spring holds the pressure until the diff reaches a position where it can lock.
If rust builds in the coils of the spring, it won’t be able to do its job.
I strongly suspect that the bleeder tube that is bundled into the wiring harness is the weak point. Running your own hose (along with the extended diff breather) is probably a good idea.
Hope this does someone some good!
BTW, the ECU must be pretty tough, as my motor read as a dead short across all connectors and the owner of the dealership I bought my Cruiser from said he drove it for a couple of weeks with the difflock light flashing :^O
When the time comes to put the actuator back on, the actuator rod has to be extended out far enough to line up with the bolt hole inside the housing.
Then, once you have the little bolt inside torqued properly, you will discover that the extended position of the rod is holding the flat mating surface of the flange away from the diff housing.
Do not force it by tightening the mounting bolts. Get up and cycle the rear actuator switch and it will suck in against the diff housing nice as you please (remember you need to be in low range for it to work).
Knowing this may save you cleaning off your dried FIPG for a second try ;^)
Glen the (US) Grinch
PS: One thing I left out of my write-up was that I regreased the gears and spring
when I put the actuator back together.
Because the sliding connectors in the gear housing will probably cone into
contact with the grease at some point, I used dielectric grease (after filling
it with Amsoil HD and changing my mind…doh!