Rear diff lock not engaging

[canman]

My rear diff lock stopped working a couple of years ago. At that time I removed it and took the cover off. Everything looked fine inside except the o-ring for the cover. I replaced it, and although the rear diff lock light was flashing, I thought it was the rear diff lock sensor until the following winter when my wife noticed that the rear tires were not spinning together.
The light flashes on the dash, but obviously it does not engage. I finally want to resolve this issue today, and have started reading a mirad of threads on the subject, but in an effort to reduce the amount of time spent trying to diagnose the problem, I have a couple of questions:

1. My front diff locks works so can I rule out the diff lock relay and the 4L transfer case position switch?

2. Is it possible that when I removed the actuator cover that I screwed up the timing of the actuator?

I'll be digging into this later this morning so any replies will be appreciated.

 

[Mattnatti]

It might be a little obvious of a suggestion but, have you tried to just move the truck back and forth a little until the light stays on and has the lock engaged?

In my truck I have to do this if I haven't engaged the locks for some time. Now I try to regularly lock them just to keep everything loose.

I am sure there will be more knowledgable advice coming but this is my thoughts.

 

[LINUS]

Did you try the 9V battery trick back before you cracked it open (or even now)? - Have you used an ohmmeter to verify you have power at the socket for the actuator?

IDK the color code wires you want to power off the top of my head, but I posted it previously - like in the last 2 yrs & since I don't post too often, if you search my posts, you should find it pretty easily.

Sometimes when they are "stuck" the 9v battery trick will work to get them "unstuck" - and worst case scenario you are just running it the wrong direction of travel.

I'd jack up the RR tire off the ground to spin it so the splines can align with the locker collar - then kick it with the 9v & you'll know if it worked once the tire won't spin.

 

[canman]

Once I got a look, I noticed quite a bit of corrosion around the motor cover and interface with the diff lock assembly. Not good as I could see that there now is probably a gap due to the corrosion pushing up on the motor housing. I tried the 9V battery, but only had 6V and nothing happened. I tried again with my battery charger set at 12V and 6A and still nothing, but I could hear the charger humming louder, meaning that the motor is probably siezed. To make matters worse, my top two bolts that secure the diff lock assembly to the axle are completely corroded such that I can't fit a 10mm socket on them. This looks like a complete rebuild. I think I saw a post from Landtank a while back where he had to rebuild the hsg. Time for a brew to think things over...

 

[BlackLS1]

i have engaged mine with the engine off key in on position and 4 low and you can hear the motors moving if you play with the diff lock switch. if you dont hear anything i would suspect a seized actuator motor.

 

[scrowley]

I have completely disassembled mine also and its not the easiest thing if you get into taking the motor apart with those little tiny brushes. My first prob was the magnets in the motor where not glued to the case anymore, like from factory. I used jb weld and put them back in place. I think this might be a common problem. Mine looked new inside but I dont think it was ever used before. I got it back to life on a bench top cycling with 9v and lubing at the same time. After all the work if I dont engage it very often it will still not want to engage without a little tap to the diff actuator case with a small hammer or other object. Seems to jump start it. To fix this I think I would need the a new actuator motor to make this thing 100% reliable. Hope this helps. This can be a very frustrating troubleshoot.

 

[LandCruiserPhil]

It does not take much corosion to stop the actuator from working.

Sounds like your actuator will be coming out in the end.

Recently had to rebuild mine and I figured out an easy way to set the timing.

https://forum.ih8mud.com/az-copper-state-cruisers/588139-locking-diff-actuator-timing.html

HTH Good luck

 

[MARKTLC80]

Are you trying to engage it on flat surface? Try to go against a curb or something, put some load on it and than it should work. That haw mine was when I first got it. Hope this helps.

 

[studawg]

It might be a little obvious of a suggestion but, have you tried to just move the truck back and forth a little until the light stays on and has the lock engaged?

In my truck I have to do this if I haven't engaged the locks for some time. Now I try to regularly lock them just to keep everything loose.

I am sure there will be more knowledgable advice coming but this is my thoughts.

Also try turning just a little bit left and right when going forward and back for it to click in.

 

[canman]

I don't believe it's an issue of trying to achieve a difference in wheel speed to get the diff lock to engage. I've had the diff lock switch "ON" for entire trail runs in the past and it never engaged. I still haven't been able to get the top two bolts off, even after applying some heat with my oxy torch. I will keep using penetrating oil on the two bolts, but I'm sure the motor is siezed. When I get the actuator off this weekend I'll post an update with pics.

 

[LINUS]

Have you tried just **tapping** the housing first, to see if the crud will let loose, then if that doesn't work, put a metal bar on the bolt heads & give 'em a good smack with a real size hammer, to try & shock the bolts to loosen up with the penetrating oil sitting on them (pref PB Blaster, or if you are a homebrew ATF/xylene/whatever guy for your climate) - bolthead smacking with heat on the bolts (MAP gas burns hotter than propane, the yellow cyls @ local store), if you aren't on a oxy/acl or propane/oxy torch setup. - Don't be afraid to get the bolts deep red before tapping, just don't twist when in color.

It might help - and pulling apart a actuator is a PITA compared to winging it & seeing if anything else works. GL

 

[canman]

I was at the dealer today to order some parts and for giggles, I asked for pricing on the rear actuator. You better be sitting down - CAN$1296.00and there is one in stk in California, but there is NO stk anywhere of the bolts used to attach it to the axle hsg...

 

[LandCruiserPhil]

IIRC the complete 3rd member is ~$850 US

 

[OGBeno]

I was at the dealer today to order some parts and for giggles, I asked for pricing on the rear actuator. You better be sitting down - CAN$1296.00and there is one in stk in California, but there is NO stk anywhere of the bolts used to attach it to the axle hsg...

I really sorry for the ride that Toyota takes the Canadians on.

That actuator can be had in the States for half that price.



Good luck.

 

[OGBeno]

IIRC the complete 3rd member is ~$850 US

A new OEM third member with actuator is discontinued from Toyota. You'd have to piece it together. Cdan sold the last one extant.

 

[lp2k]

ugh man this is like my EBCTM/ABS module for my corvette, cant be rebuilt and its discontinued ... wtfaaacccckkkkk

 

[canman]

I finally got both the upper bolts off. One came off with some heat, but the upper rear one was too rounded, so I ground off the head. In the process, I was tapping on the hsg, and now the upper right ear is cracked. However, the hsg does not want to come out of the axle. It feels like there is some kind of spring force holding it in. Any idea was I need to do to release it from the hsg?

 

[canman]

I got the actuator out after removing the sensor cover and the screw that locks the actuator shaft to the fork.
The actuator is now apart and it is not pretty. There is lots of dirt and debris inside both the electric motor and the gear hsg. The motor rotor is even stuck to the magnets.


For those in the rust belt and with lockers, I suggest checking the seal between the motor cover and the hsg. Corrosion opened mine up and that's how the dirt got in.

 

[canman]

Ordered the diff lock today from CDan. It was the only one in stk. Price was much better than here in Canada (US$713.00 vs CAN$1296.00). Hopefully it will arrive this Friday.

 

[BlackLS1]

did you look for any used ones?