'97 Automatic Prado, KD-KZJ95W, centre diff lock issues

[Bert]

I apologise if this has been discussed in a previous thread but I couldn’t find one like this while searching through the forums last night. Ok folks, I’ll try and describe exactly what I did before everything went south. After driving home in my automatic ’97 Prado, and at the bottom of the access road to my house, I thought that I’d engage the ‘HL’ centre diff lock just to ‘turn it over’ as this was last engaged back in early March when I paid a visit to Julian at Overland Cruisers. So, at the bottom of my lane which is gravel with a slight gradient, I put the shift lever into Neutral (N) and pushed the transfer lever from ‘H’ to ‘HL’. The light on the dashboard came on to let me know that it was engaged. I drove slowly up the lane which is about 100 yards, turned into my back garden and then stopped. I put the transfer lever back into the ‘H’ position, but noticed that the light on the dash stayed on. The confusion started here. Whilst stationary, with the front wheels in line, I moved the transfer lever back into ‘HL’, then back into ‘H’. Still the light remained on informing me that the centre diff lock was still engaged. At this point I moved the transfer lever through all the ranges, ‘HL’, ‘N’ and ‘LL’ then back down to ‘H’; still the light stayed on. At this point I decided to ignore it, leave it in ‘H’, the shift lever in ‘P’, turned off the engine and went in for a cup of tea. A couple of hours later, I got brave again and got back in. Ignition on, engine running with shift lever still in ‘P’ the centre diff light still on with the transfer lever in ‘H’ I decided to drive it back down the lane and around the oval to see if I could shake it loose or something. I reversed out of my garden and I’m sure that there was some ‘knocking’ from the rear axle but can’t be sure. Then I drove back down the lane to the bottom. At this point I had to turn right which was a little tight due to access issues and the knocking or shuddering occurred again. I had to reverse again a little to get by a conveniently parked white van, and then I proceeded to drive around the estate at low speed, and then back up my lane. All the while the diff lock stayed on, even though the transfer lever was in ‘H’. It wasn’t until I got back to my garden that I think I moved it from ‘H’ to ‘HL’ and back to ‘H’ that the light finally went off. Brilliant I thought, though still confused by the whole experience. I thought that it may be down to complete lack of use. Anyway, if you are still awake and reading this, a few days later I tried it again. With the car in ‘N’, I moved the transfer lever from ‘H’ to ‘HL’……. Nothing happened; no faithful little light came on the dashboard. I moved up and down through the range on the transfer lever, still no light came on. So, can anybody tell me what has happened, have I murdered my rear axle somehow? Is it just stuck? All helpful comments greatly appreciated. Cheers. Oh, just a footnote, thinking on it I think the nocking or shuddering only occurred with the transfer lever in ‘HL’ and when the front wheels were turned as I manoeuvred so this fits with the wheels moving at different speeds while turning left or right, so I THINK this is normal???? Please help.

 

[BobMurphy]

Hi there,

This sounds almost 'normal' for a Centre Diff Lock that hasn't been used for a long time.

There are two Selector Shafts in the Transfer Box - The Right-hand one (from the Driver's seat) operates the Centre Diff Lock and the Left-hand one operates the High/Neutral/Low gear change.

The High/Low is a rigid assembly and can only be used at very low speed in a manual car (which has Synchromesh) or with the Auto Box in Neutral in an Automatic (it doesn't have Synchromesh).

The Centre Diff Lock assembly is sprung. When you move the Transfer Lever you move the shaft in the Transfer Box but the Selector Fork is sliding on that shaft with a large spring on each side. Shifting the lever simply tensions the spring and you then wait for nature to take its course.

You can see the springs on the Diff-Lock Shaft here (in the "Diff Locked" position):



If the Transfer Box hasn't been 'exercised' for a while the gears on the main shaft can become corroded and then the Selector Fork and Diff Lock gear won't slide

The indicator lights are worked by the sliding Selector Fork so it tells you what has actually happened - not what the Transfer Lever is doing.

The 'knocking' when reversing and turning the front wheels is simply "Transmission Wind-Up" as the front and rear axles take different paths with the centre diff locked.

I would drain the oil from the Transfer Box and check it. If it looks 'muddy' you have water in there and there will be rust. I have had two Transfer Boxes from Automatic cars that have been very rusty inside. They can be cleaned-up but its a complete strip-down job I'm afraid.

You need to avoid this:



If the oil is OK - keep using the car and keep 'exercising' the Transfer Lever - it will eventually free everything off .

Bob.

 

[AndyCook]

Better to do the diff lock tests on a long straight road.
I often found I needed to blip the throttle to get it to unlock or lock after moving the lever.
It is very rare that the diff lock can unlock and lock when vehicle is stationary

 

[Shayne]

Lockers need wheels to move to engage/disengage so nothing was going to happen while you were parked and like as not had you drove about a bit outside the house it would have disengaged . I would guess leaving it locked over night allowed it to stick so i would exercise it in and out 10 times before the bottom of the lane and the same coming back and then change oil .

The knocking/shuddering is normal its the truck telling you to disengage the locker because you don't need it here .

 

[Bert]

Hi there,

This sounds almost 'normal' for a Centre Diff Lock that hasn't been used for a long time.

There are two Selector Shafts in the Transfer Box - The Right-hand one (from the Driver's seat) operates the Centre Diff Lock and the Left-hand one operates the High/Neutral/Low gear change.

The High/Low is a rigid assembly and can only be used at very low speed in a manual car (which has Synchromesh) or with the Auto Box in Neutral in an Automatic (it doesn't have Synchromesh).

The Centre Diff Lock assembly is sprung. When you move the Transfer Lever you move the shaft in the Transfer Box but the Selector Fork is sliding on that shaft with a large spring on each side. Shifting the lever simply tensions the spring and you then wait for nature to take its course.

You can see the springs on the Diff-Lock Shaft here (in the "Diff Locked" position):

View attachment 109793

If the Transfer Box hasn't been 'exercised' for a while the gears on the main shaft can become corroded and then the Selector Fork and Diff Lock gear won't slide

The indicator lights are worked by the sliding Selector Fork so it tells you what has actually happened - not what the Transfer Lever is doing.

The 'knocking' when reversing and turning the front wheels is simply "Transmission Wind-Up" as the front and rear axles take different paths with the centre diff locked.

I would drain the oil from the Transfer Box and check it. If it looks 'muddy' you have water in there and there will be rust. I have had two Transfer Boxes from Automatic cars that have been very rusty inside. They can be cleaned-up but its a complete strip-down job I'm afraid.

You need to avoid this:

View attachment 109794

If the oil is OK - keep using the car and keep 'exercising' the Transfer Lever - it will eventually free everything off .

Bob.

Hello Bob. Thanks for the reply. I'm pretty sure that the oil was ok back in March, but I'll have a look and check anyway, hopefully at the weekend. In the meantime, I'll keep jigging it to see if it does free up. I was a little crestfallen as I'm hoping to waste lots of money putting new tires, shocks etc on her sometime in the not too distant future but don't want to plough too much cash in if she's nearly dead.

 

[Bert]

AndyCook and Shayne, thanks for your input too. I'm hoping that it is just a little stuck due to not being used. I've only had her since March, the previous owner had it since she was imported and I'm pretty sure he never used the transfer lever. I'll keep getting jiggy with it and see what happens. As I said to Bob, I'm pretty certain that the oil was good back in March, but will have a look anyway. Much appreciated fellas.

 

[BobMurphy]

I'll keep jigging it to see if it does free up. I was a little crestfallen as I'm hoping to waste lots of money putting new tires, shocks etc on her sometime in the not too distant future but don't want to plough too much cash in if she's nearly dead.

She isn't dead - this is fairly normal.

Just get out there and use it (with fresh oil ).

Bob.

 

[JakeM]

With a manual box and the difflock stuck, reversing often helps free it. This maybe the same for an auto. Anyone know?

 

[froggy Steve]

I usually have to reverse to clear the diff lock, not always though, probably 80℅ of the time? It doesn't get used very often though.

 

[Bert]

I tried it again last night and managed to get it back on, then it stayed on and wouldn't disengage again so I think it will be just a case of working it back and forth a bit to work it. If I can crawl under her at the weekend, I'll check the condition of the oil in the box. Cheers guys.

 

[AndyCook]

Did you try reverseing in a straight line or driving forward in straight line and blipping the accelerator to allow the car to surge forward and then coast, I often found this would help, it would do its stuff after the brief acceleration when coasting and less load on transmission

 

[Bert]

Did you try reverseing in a straight line or driving forward in straight line and blipping the accelerator to allow the car to surge forward and then coast, I often found this would help, it would do its stuff after the brief acceleration when coasting and less load on transmission

Hi Andy. I found reversing in a line does help. I will play with her a little more when I get home. The car that is.

 

[Shayne]

back and forth a few feet should do it which may save some time and if you can find a bit of grass or gravel so wheels can slip without damaging the drivetrain some full lock turns might help .