Repairing Differential E-Lockers

[xprmntl]

Neither of my electronic differential locks was engaging, so I thought I was unfortunately in need of undertaking an E-locker repair. I searched 80 threads for the what and how of removing, tearing down, rehabilitating and reassembling stuck lockers, but was a bit disappointed to find there wasn’t just a single, comprehensive thread. I took it upon myself to collect the best information and cobble together a more comprehensive guide for diagnoses and repair for myself and others. It is attached here in Word file format by our loving moderator, Romer. Thankfully, my issue turned out to simply be a loose switch connector. May yours go as smoothly.

If there is something that I missed, or some gross errors, please feel free to PM me with your thoughts and I’ll edit where appropriate.

Thanks to all of my predecessors who I stole from to put this document together, largely Raventai, FJBen, Photoman, Landtank, Gauge, & Beowulf.

 

[nuclearlemon]

there is a thread here on retiming the rear locker because toyota doesn't consider that a servicable item and a really talented mofo has saved us a serious headache since that's usually the one that needs the work. the front locker motor is servicable and the instructions are in the fsm.

 

[xprmntl]

I managed to convert my Word file to PDF, so I was able to upload it without Romer's help

there is a thread here on retiming the rear locker because toyota doesn't consider that a servicable item and a really talented mofo has saved us a serious headache since that's usually the one that needs the work. the front locker motor is servicable and the instructions are in the fsm.

It's posts like this that can be really annoying to people seeking knowledge on repairs from this great forum. It lends nothing to the conversation. No username reference (talented mofo?), no link reference,& no elaboration (why is the front serviceable while rear is not?). And as far as I've seen, there is no Factory Service Manual (FSM) instructions for tearing down and rebuilding a front locker actuator (front and back are mostly equivalent in internal structure, though outputs are different--rear has a push rod and front has a gear), though there are instructions for the front on how to position the output gear and remount.

And yes, I do address "retiming" of the rear locker (ensuring the Shift Lock Fork Shaft is in the proper position when remounting). I think you are referring to posts made by Raventai and a few others. These posts, while helpful, are in no way complete in themselves, and neither is mine, but it seeks to be a more encompassing document so people don't have to peck around for hours in the forum gleaming nuggets of knowledge from here and there.

 

[nuclearlemon]

what link?

can't remember who did the thread, hence no user name, you said you found one when you searched, so you may already know who did it. i posted about it so you would know if you found the one on retiming the locker actuator. judging by names mentioned, you've seen the articles on rebuilding the actuators, so why are you starting yet another thread

why doesn't toyota service the rear, i don't work for toyota, so i don't know why. you would have to bring that up with their engineers. what the fsm shows is what toyota considers service. if you need to know how to rebuild an electric motor, you may need to talk to an electrician

Please refrain from posting to this link until Romer manages to get the Word document linked.
It's posts like this that can be really annoying to people seeking knowledge on repairs from this great forum. It lends nothing to the conversation. No username reference (talented mofo?), no link reference,& no elaboration (why is the front serviceable while rear is not?). And as far as I've seen, there is no Factory Service Manual (FSM) instructions for tearing down and rebuilding a front locker actuator (front and back are mostly equivalent in internal structure, though outputs are different--rear has a push rod and front has a gear), though there are instructions for the front on how to position the output gear and remount.

 

[Romer]

Steve, thanks for the write-up. I am sure it will be helpful to others. I will add it to the FAQ

Nuclearlemeon is another 80's moderator, so I would be very nice to her

 

[asutherland]

Dude... why couldn't you have done this say a year ago?

 

[Rwhat]

He is right, however there is info on the actuator rebuilds, but it not easy to find. Landtank did a great write up however it was only recently. Before i did mine i searched and only found bits and pieces. There should be a FAQ on rebuilding them. After tearing mine apart, there isn't much to them.

 

[guthriealexander]

This is great thanks so much for taking the time to put this together im going through this same process now.

 

[xprmntl]

This is great thanks so much for taking the time to put this together im going through this same process now.

Please let me/us know how it goes and what was helpful and what might need amending in the document. Good luck.

 

[asutherland]

Dude... why couldn't you have done this say a year ago?

By the way... what I meant to say was THANKS for the hard work in preparing that document! I've saved it for the next time my locker motor needs rebuilding.

 

[EricG]

Nice job! FWIW, I had my rear actuator apart this past fall and had to figure out the timing on it. The picture below shows the correct orientation of the rear difflock actuator internals when the locker is disengaged. Basically, you pull the shift fork all the way to the left, then line up the actuator shaft and put in the bolt. Then put the clockwork mechanism in, oriented as shown.

Here's the thread in our club forum:
https://forum.ih8mud.com/co-colorado-land-cruisers/523324-80-series-locker-computer.html
(ignore the thread title - problem was not the ECU)

 

[jdeitch]

Excellent article. On the '94 I just got the rear locker only blinked. After a test drive on the dirt I determined it was in fact locking up. After reading your article I checked the locker position switch and BINGO. I called NAPA and they could get the switch for $27 + $5 shipping for special order. With nothing to lose I carefully rebuilt the electrical portion of the switch and ALL is good now. Zero $ fix.

 

[xprmntl]

Thanks for the feedback. Glad it helps. I'll add EricG's input on innards orientation when I get time.

 

[astr]

Wires Switched

I followed your writeup on rebuilding my front locker actuator. Great write up - many thanks. It was a great help.

When I got the actuator all together and tried it connected to the truck, when I selected front lock, the final gear on the actuator turned the wrong way. I had pulled the pins out of the connecter and put them back in the order that your write up states. I then reversed the motor drive pins (Green and Green/Red) and it worked correctly. Since I didn't have to reglue the magnets and had not changed any wiring within the actuator, I was puzzled as to why I was having this problem so I checked the wiring on a brand new front elocker and sure enough the wires were reversed from what your diagram shows. It should be: 1) Blank, 2) Green/Red and 3) Green. The limit switch wires are correct.

This error would only affect those who might remove the pins from the connector body.

Again, thanks for the great writeup,

 

[xprmntl]

Correction to PDF

Astr,

Good catch. I got the wiring designation from a Raventai post: https://forum.ih8mud.com/showpost.php?p=172256&postcount=7
This thread may have had people switching their magnets where they could have been switching improper wire placement.

I checked around, and though there is reference to different years being wired differently, I believe you are right:

Green is locker connector position 3 and Green-Red is position 2. Positive to Green gives lock and positive to Green-Red gives unlock.

Here's a good wiring diagram from 2ndGenToyotaFan: https://forum.ih8mud.com/showpost.php?p=5565669&postcount=1

 

[Kief]

Thread resurrection: My rear locker wouldn't engage. I had some wiring that was cooked in the harness and replaced it. I pulled apart the locking mechanism and the motor was full of rust. Now I'm trying to find out if my computer is good. No relay "click" when on "RR", "click" on the "FF/RR" but I think that is just the front. I am only getting power at the indicator switch in the rear. The center diff lock is on and I can engage the front- I tested all my wires for continuity, the two hot leads to the motor, two position indicator switches and then the ground. I should have power at either of the position switches and also jumper either one to ground to get power at the motor leads, correct? I jacked up all four tires and no, the rear didn't engage. I think I have a dead relay on my computer, are these replaceable?

 

[Kief]

I tested the terminals of a known good fjz80 with lockers and had the same results, I think I should be looking for mill-volts instead of volts. I didn't swap over to milli-volts but will know if My computer is good if it engages the locker when its all reassembled..

 

[xprmntl]

Others have had issues with pin connection corrosion causing this issue at the locker connections at the locker ECU under the right front kick panel. I would suggest you first clean all terminals there. You can also swap rear locker ECU connectors with the front to see if it's something at the ECU or downstream. The ECU unit can be pried apart. The relays are soldered in. Part number has been reported to be: Omron relay P/N G8S-114P-02T . I believe this part is no longer manufactured and the replacement looks to be G8SN-1C7-CUK, but doesn't seem to be available anywhere in the US. Best to contact OMRON to source new. These appear to be the same as power window relays in POWER WINDOW RELAY ASSEMBLY found in 4-Runners and MR2s, if you're out picking parts. If the relay is out, people have cut them open and reconditioned the contacts, then taped or glued them back up: https://forum.ih8mud.com/threads/4runner-rear-window-relay-repair.173958/

If the relay check doesn't pan out, another cause for a clicking relay at the locker ECU has been the ground in the locker itself. The ground triggers that holds the relay closed comes from the position/wiper switch in the actuator. The grease can harden or get contaminated (often from a missing or severed breather tube) and lead to the poor connection.
https://forum.ih8mud.com/threads/bad-locker-ecu-are-relays-replaceable.408534/

Wiring diagrams for F/R ECU at the bottom of this thread: https://forum.ih8mud.com/threads/locker-ecu-problems-searched.745621/#post-8602749

BTW, The center differential lock ECU is under the left side (driver side) kick panel, labeled " transmission control relay ." Here's a good link for CDL issues for anyone that follows this thread:
https://forum.ih8mud.com/threads/cdl-relay-chatter.597743/#post-7663311

 

[Kief]

Most helpful- I will check for connection quality. My problem was in the motor, the wipers and actuator were well greased with minimal corrosion.

 

[Hoosier Daddy]

Nice info. I used this thread today when I was troubleshooting a rear locker that would not engage.

CDL and front locker worked well, but could not get the relay click (in the passenger kick panel) for the rear locker. Pulled the diff ECU plug and got no ground for the rear locker at terminal 11, so figured there was a connection issue at the rear actuator or with the position switch inside. I pulled the plug at the rear actuator and it was clean inside. No continuity between terminals 6 and 4 (there should be continuity when unlocked). Pulled the actuator completely off and checked again just to be sure. It now had continuity between 6 and 4. Hmmm. It just fixed itself.

Since I had the actuator off, I figured I would open it up and see what's up. Inside the actuator looked like new. Beautifully clean. None of that rusty mess seen so often in these threads. I did notice that corrosion was starting to creep under gear cover by the area of the motor, but no moisture had made it onto the actual case yet. I cleaned all that up and put it back together. Re-installed on the truck and works fine.

My guess is that the pristine original grease had gotten hard inside the gear case and caused a bad connection at the position switch. If this were to happen again, I would try moving the motor with a 9V battery first, before taking it all apart. I figure the movement of taking off the actuator is what caused the electrical connection to be re-established inside.