Landcruiser 90 series rear diff repair help please .

[Shayne]

After stripping off the under body protection and sidesteps etc and waiting for my mate to arrive with more jacks so i could fit the body lift i started looking at the rear diff . It seems to be in very good condition compared to most i've seen and i can't help thinking there is very little wrong with it .

Would i be right in thinking that being electrical the dashboard switch actually moves some sort of sleeved rod to engage the locker ?

Assuming this is correct is there any reason i should not (if i can find a spanner big enough) undo the nut holding the grey electrical connector which i have tried to picture below . My hope is if i can remove it that i might be able to free up the rod which i'm assuming has corroded meaning the electrics don't have the power to move it .

I would be grateful for any advice as i have searched in vain for pics to show whats inside .

PS I am an amateur and don't have a mechanics vocabulary so please don't start talking about flux capacitors and stuff , i am however pretty good with my hands and have yet to come across anything i couldn't fix .

 

[AndyCook]

there is no nut holding the grey connecter on
it has a couple plastic locking tabs on it which needed to be pressed in with your fingers whilst you carefully wiggle it and pull it off

EDIT: actually i havent removed that grey connector, i was thinkign about the one of the diff lock accuator itself
that connector you refer to is for the sensor that determines whether or not the difflock is locked or not locked, and then lights up the dash light

the dash switch only works when truck in low range

the electric motor turns a spring loaded cog via a worm drive,
the spring loaded cog then moves the accuator rod - (a bit like a steering rack = rack and pinion)
to engage and disengage the locker

the actual accuator rod for the locker is on the insideside of the diff casing

i have annotated your photo

red arrow - is the end cap where the rod is located
and the blue circles show the nuts holding this end cap on

when my locker played up in lakes, and stayed locked...
i had to remove the end cap and use pliers to pull the rod inside slightly futher out to disengage the locker

so it is this end cap you need to remove, not the electrical connector!

however, its more likely the accuator has corroded internally
when in low range, and you use the dash switch does the rear locker light flash?
and can you hear the accuator motor moving or making a noise
you might need someone to control the dash switch whilst you listen

 

[Shayne]

Excellent thanks Andy i can now clean the connections and the rod , my instinct told me the moving part must connect directly to the electric power supply and nut at the base of the connector suggested the same , glad i was wrong

 

[AndyCook]

i think the nuts holding the cap on are 10mm

here is a diagram of the axle

I have highlighted in yellow the internals - the cog on the difflock accuator, and the teeth which it drives on the shift lock for (41451)
the rod that goes through the shiftlock for is part 41462K and you can see the end of this under the end cap - part 41469A

that switch/relay you were thinking of removing - is shown here too where it says "REFER To FIG 84-01 (PNC 84222E)"

 

[Shayne]

In LL gear with rear diff switch on centre diff locks but rear diff light flashes then remains solid red . I'm half deaf but the mrs says she can hear a whirring sound when i turn the diff switch even without the engine running .

Given how clean the truck was when i bought it and the fact it had only covered 90k miles i figure its likely lack of use rather than anything else thats caused it to seize .

 

[AndyCook]

it might not lock if car isnt moving, as stuff needs to get aligned inside - the motor wirrrs and tensions the "clock style" spring, which will then push the accuator fork/rod into position when the diff internals allow

i found best way to test was to put back end of truck on axle stands, so back wheels off the ground, chock front wheels, take handbrake off
you should then be able to turn a back wheel by hand
then i could activate the locker in LL with engine off, but key in ignition,
i would walk to back of truck and turn a back wheel by hand and i would hear the locker engage with a clunk and then wouldnt be able to turn the wheel anymore

this will then allow you to determine if the locker is working or not - the fact your mrs can here it whirring is good news
and if you cannot turn the back wheel when you have engaged it, means back axle locked, you can then try disengage etc
if it seems to be working but light still flashing, that suggests the locker posisiton sensor/switch/relay is buggered

 

[Shayne]

Great test Andy but i've been trying to engage the locker for a while just hoping it will free up , full lock circles on sand was the one attempt i most hoped to succeed but it didn't budge . Will report back to reveal what i find in 10 minutes

 

[Shayne]

Somebody has already been at it by the looks coz the nuts were rounded (first i've found on the truck) and the cover is stuck fast with what i guess is some sort of instant gasket so i'm back trying to pluck up courage to get violent with it while knowing the casing is renowned for just disintegrating !


That orange bit you see is a bit of the gasket stuff i chiseled off .

 

[adrianr]

Give the actuator some careful taps with a hammer. That may free it up.

 

[Shayne]

OK covers off and what i can see of the pin looks shiney and new , can i pull it out , though it won't easily be removed , or as Adrian says should i try tapping it in . The truck is back in hh and the diff switch is off .

 

[AndyCook]

tapping what? the rod inside the hole or the accuator assembly?
they are separate bits

I would leave the accuator bolted onto the axle for now - no point disturbing it yet
I think Adrian is talking about the accuator (the part with the motor and wires going into it!)

did you try the test i said with the wheels in the air?

when the rod is fully pulled towards you the locker is unlocked

you can try engaging the locker with dash switch - turn to lock
then pushing the rod away from you through that hole where you took the endcap off and then see if diff is locked
i think if both back wheels in the air, and rear diff unlocked you can turn one back wheel and the other should turn the opposite way
and when you lock the locker you shouldnt be able to turn a back wheel by hand (cos the centre diff is also locked)

maybe moving the rod, and using the locker control switch could free-it off if it is stuck

if none of this works, you will have to remove the accuator, but be warned it often comes off in bits....

 

[Shayne]

Its not the pin i fired her up engaged LL and turned the rear diff switch , the pin went in instantly no trouble at all . So looking at your diagram Andy i'm guessing i have broken teeth in there

I will try the test maybe its just the dash light telling lies !

 

[silvercruiser]

In LL gear with rear diff switch on centre diff locks but rear diff light flashes then remains solid red . I'm half deaf but the mrs says she can hear a whirring sound when i turn the diff switch even without the engine running .

Given how clean the truck was when i bought it and the fact it had only covered 90k miles i figure its likely lack of use rather than anything else thats caused it to seize .

Am i missing something here? you say the rear diff lock light flashes and then goes solid red. I thought this means that it is now engaged.

 

[Shayne]

Centre diff goes solid orange when engaged I'm sure my rear diff only flashed red before i started messing with it today ????????

 

[AndyCook]

Silvercruiser - i think Shayne meant the centre locker light there


try the wheel turning test Shayne - i suspect its the sensor for the dash light playing up if the shiftlock is moving when you activate the accuator via dash dial
the light flashes before engaged, then goes solid red when locked
also rod may not be moving far enough until you lift the back end and turn the wheels by hand


as i found out in lakes after i used rear locker on some tricky rock steps, the light went off on dash when i turned dial to off, but when i went back on tarmac i could hear and feel the back wheels scrubbing when i turned corners....
the light was off but locker was still on, the accuator still worked, but wasnt moving the shiftlock out quite far enough to disengage the locker

 

[Shayne]

The plots thickens lol . Jacked up the rear and cant budge either wheel , the centre diff must be engaged before the rear diff will work , hence i would have to jack all 4 wheels off the ground to make use of the test . Unfortunately i dont have anything to prop it with and i dont have 4 jacks . However i'm thinking with the gearbox in neutral and all diffs locked only the front wheels are preventing me from spinning the rear wheels hence the rear diff must be engaged . Does that make sense ?

 

[AndyCook]

ah sorry
try putting gearbox in neutral as well

i am sure i did the test with only back wheels in air

try unlocking the rear diff and turning wheels again?

if only the centre diff is locked, gearbox in neutral, handbrake offand back wheels in air, you should be able to turn one of back wheels by hand

 

[Shayne]

I remembered the handbrake honest i did . Both rear wheels spin independent of each other when H is selected and gearbox is in neutral . Centre diff engages in anything other than H . Put it into LL and switched rear diff on and i still cant spin wheels with the front grounded but a half inch play tells me the rear wheels are locked together

 

[AndyCook]

can you unlock them as well?

good news that they are locking

what is the rear locker dash light doing?

with back wheels locked together and centre difflocked and gearbox in N and back wheels in air, you wont be able to turn back wheels by hand, but will get that slack you mention

 

[Shayne]

3 flashes and solid red even without moving the truck ! I guess it just needed waking up . Thanks for your help Andy and thank you to silvercruiser for making me think about the light again , i can imagine myself knee deep in bits of metal then suddenly thinking "hold on that light was solid red"

Just realized i've got no gasket seal to replace the cover with but i reckon plumbers mate is up to the job , great stuff it never solidifies and is always waterproof might be a solution for others who have waterproofing problems ?