Diff locks.

[Tinerfeño]

My '95 was so thirsty

Mine is a 200Tdi

 

[Tazzieman]

Mine is a 200Tdi

Well that will serve you for the next 30 years , or until Greta Thunberg lets your tyres down

 

[hopefulkiwi]

fwiw toyota landcruiser 70 series also lock the diffs rear then front. Its a rotary switch so front can not be engaged by itself

 

[Tom D]

I think there’s a bit of confusion regarding the lockers. As in my earlier post the indicator lights have little relation to the lockers themselves. I have used them in anger several times now and found that the lockers engage pretty much instantly. They also disengage quickly. The indicator lights however are a different story. Best just to ignore them. You know when the lockers aren’t engaged as one wheel will spin while the other doesn’t. And you’ll know when they are as the car won’t want to go round corners.

 

[Spjnr]

I think there’s a bit of confusion regarding the lockers. As in my earlier post the indicator lights have little relation to the lockers themselves. I have used them in anger several times now and found that the lockers engage pretty much instantly. They also disengage quickly. The indicator lights however are a different story. Best just to ignore them. You know when the lockers aren’t engaged as one wheel will spin while the other doesn’t. And you’ll know when they are as the car won’t want to go round corners.

Mine too, no issues. the indicator lights are fed by wheel speed sensors, so the delay is due to people mainly going straight when trying to disconnect lockers

 

[255/85]

I'd like to be able to lock the rear diff while still in Hi Range/Center Locked (no need for the front until down and dirty). Having the rear locked is great help getting through heavy snow patches while essentially still on level roadway - paved or not. Having to stop to go in and out of low range or wait for the traction control to kick in seems kinda silly. No? It would only take a software update to make it happen.

 

[Clark Kent]

I think there’s a bit of confusion regarding the lockers. As in my earlier post the indicator lights have little relation to the lockers themselves. I have used them in anger several times now and found that the lockers engage pretty much instantly. They also disengage quickly. The indicator lights however are a different story. Best just to ignore them. You know when the lockers aren’t engaged as one wheel will spin while the other doesn’t. And you’ll know when they are as the car won’t want to go round corners.

What is unclear is if ABS, ESC and Brake Traction Control (BTC) are disabled for as long as the indicator light remains on after diff lock disengagement. i.e., does the BCM rely on the signals from the wheel speed sensors to re-enable ABS, ESC and BTC? I think this would be the case, which means there is no traction assistance available until the indicator light goes out. This includes HDC. ABS and ESC are less important in a low traction off-road setting where diff lock use would be considered.
Has anyone noticed or specifically tested this? Does BTC or HDC operate after the diff lock is turned off with the indicator light still on?

 

[Tom D]

What is unclear is if ABS, ESC and Brake Traction Control (BTC) are disabled for as long as the indicator light remains on after diff lock disengagement. i.e., does the BCM rely on the signal from the wheel speed sensor to re-enable ABS, ESC and BTC? I think this would be the case, which means there is no traction assistance available until the indicator light goes out. ABS and ESC are less important in a low traction off-road setting where diff lock use would be considered.
Has anyone noticed or specifically tested this? Does BTC operate after the diff lock is turned off with the indicator light still on?

I think you are right, and it is a problem. Imagine you climb a steep razor back hump, difflocks engaged. Then at the summit you want to engage HDC to descend the other side.. you can’t because the car thinks the lockers are still engaged.

 

[Jean Mercier]

What is unclear is if ABS, ESC and Brake Traction Control (BTC) are disabled for as long as the indicator light remains on after diff lock disengagement.

Ask Ineos, they will respond "built on purpose " ...
Sarcasm of course, but as owners, we are entitled to know how it works

 

[Clark Kent]

Sarcasm noted Jean, but if you don't mind I'll seek my flagellation elsewhere

 

[Tinerfeño]

I'd like to be able to lock the rear diff while still in Hi Range/Center Locked (no need for the front until down and dirty). Having the rear locked is great help getting through heavy snow patches while essentially still on level roadway - paved or not. Having to stop to go in and out of low range or wait for the traction control to kick in seems kinda silly. No? It would only take a software update to make it happen.

Usually you can go up to 40-50 km/h in low range. Isn't that enough in deep snow? And on high range you have the traction control.

I use to engage low range much earlier that it is actually needed just to avoid need to change it suddenly. On manual gearbox it is though easy to change high>low or low>high without stopping. Center lock engaged also basically always on off-road, perhaps except easy and hard sections.

 

[Tinerfeño]

I think you are right, and it is a problem. Imagine you climb a steep razor back hump, difflocks engaged. Then at the summit you want to engage HDC to descend the other side.. you can’t because the car thinks the lockers are still engaged.

Lockers engaged you don't need HDC.
I find HDC practically unnecessary at least in conditions we have.

 

[Tinerfeño]

Mine too, no issues. the indicator lights are fed by wheel speed sensors, so the delay is due to people mainly going straight when trying to disconnect lockers

Sure about this?

Usually diff locks don't lock or unlock instantaneously if the teeth mate when trying to engage or there is pression on the locking teeths when you try to disengage. Separate microswitch may be used to indicate the actual position of the locking teeth. Therefore the display may be right despite state of the switch.

If speed sensors data is used the locking/unlocking may not be shown correctly.

 

[255/85]

I think you are right, and it is a problem. Imagine you climb a steep razor back hump, difflocks engaged. Then at the summit you want to engage HDC to descend the other side.. you can’t because the car thinks the lockers are still engaged.

This relates to my question for @Barney in a different thread where I queried "If you are climbing a grade with fr/rr diff locks engaged and don't make it all the way up, can you immediately disable the lockers and activate HDC to reverse back down?

He was going to check and reply when he was able.

 

[DaveB]

Sure about this?

Usually diff locks don't lock or unlock instantaneously if the teeth mate when trying to engage or there is pression on the locking teeths when you try to disengage. Separate microswitch may be used to indicate the actual position of the locking teeth. Therefore the display may be right despite state of the switch.

If speed sensors data is used the locking/unlocking may not be shown correctly.

This is how it the locker works

View: https://www.youtube.com/watch?v=nT_H6rpd-Ck

The indicators are operated by speed sensors in the wheels.
The wheels have to be travelling at different speeds, eg unlocked, before the indicators go off.

 

[255/85]

Usually you can go up to 40-50 km/h in low range. Isn't that enough in deep snow? And on high range you have the traction control.

Possibly this would be fine but we often travel bare pavement with occasional patches of snow and ice that are either in shadow or missed by plows or have tumbled down after the road was previously cleared. It's mostly just what we are used to as we have automatic lockers in some of our vehicles. All that is required is to slow down to the appropriate speed and proceed through the difficult patch.

I use to engage low range much earlier that it is actually needed just to avoid need to change it suddenly. On manual gearbox it is though easy to change high>low or low>high without stopping. Center lock engaged also basically always on off-road, perhaps except easy and hard sections.

Please correct me if I'm wrong but it's my understanding that a Grenadier must be (nearly) fully stopped and the transmission placed in neutral before shifting from high range to low range and vice-versa. In and out of center lock can be done on the fly.

 

[Tinerfeño]

Please correct me if I'm wrong but it's my understanding that a Grenadier must be (nearly) fully stopped and the transmission placed in neutral before shifting from high range to low range and vice-versa. In and out of center lock can be done on the fly.

That's for non-experienced and for automatic transmissions

Hi-Low with manual transmission it is very simple with double clutching. Autobox is difficult and I don't recommend trying. Automatic does it more easily at slow speed than standstill.

Center diff lock doesn't care about speed, just wheel spin. I have engaged it on Land Rovers at 80 km/h.

 

[Tinerfeño]

The indicators are operated by speed sensors in the wheels.
The wheels have to be travelling at different speeds, eg unlocked, before the indicators go off.

This is slightly stupid. If you disengage locker and continue straight it thinks that your locker is engaged despite it is not locked.

 

[DaveB]

This is slightly stupid. If you disengage locker and continue straight it thinks that your locker is engaged despite it is not locked.

This is a problem with all indicating systems.
Alternative is to display that you have instructed the locker to unlock by a switch, which doesn't tell you if it actually has unlocked, only that you requested it to.
Ineos system says

• I know you asked for it to unlock
• I can see that the switch asked the relay to unlock it
• I will get back to you when I have proof that it has happened.

I once queried these strange indicating lights that a company wanted in their control room and office.
They advised they had some critical fans that needed to be running for their manufacturing process and had to know they were operating.
I advised the lights only showed the status of the control circuit, the fans could be on the back of a truck 100 kms away.
Shocked looks followed by heated discussion with design engineer.

 

[Clark Kent]

This is a problem with all indicating systems.
Alternative is to display that you have instructed the locker to unlock by a switch, which doesn't tell you if it actually has unlocked, only that you requested it to.
Ineos system says

• I know you asked for it to unlock
• I can see that the switch asked the relay to unlock it
• I will get back to you when I have proof that it has happened.

I once queried these strange indicating lights that a company wanted in their control room and office.
They advised they had some critical fans that needed to be running for their manufacturing process and had to know they were operating.
I advised the lights only showed the status of the control circuit, the fans could be on the back of a truck 100 kms away.
Shocked looks followed by heated discussion with design engineer.

Dave is onto it.
Open-loop control versus closed-loop control.
Open-loop: Initiate a change and assume it happened. Update the indicator status regardless of the result. No feedback that the change occurred.
Closed-loop: Initiate a change and positively verify that it happened via a feedback mechanism. Indicate the change only if successful (else display a fault, etc.).

Use of the wheel speed sensors is a closed-loop control system. The light only goes out if the BCM can prove via wheel speed feedback that the diff has unlocked.
If Ineos used open-loop control and assume the diff has unlocked, then allow HDC or BTC to brake a single wheel on that axle, the traction control would be ineffective (if the diff is still locked) because both wheels would stop turning when either side brake was applied. That scenario has potential to cause damage to the driveline.