Finally I've found how it works (Murano AWD)

[teonek]

LINK> http://www.nissanpress.co.uk/nissan/...7292murano.htm

It's about European Murano but there is text how ALL_MODE 4x4 in our Murano works, there is also information about changes in euro MO in comparison to US MO.

So how it works:

"The system has two modes – Auto and Lock – selected via a switch on the dashboard. As the name implies, Auto is a ‘set-and-forget’ mode and for much of the time the system operates in front-wheel drive for optimum fuel efficiency. Engine torque is transferred to the CVT transmission and to the front transfer case, and the transfer case in turn is in constant mesh with, and driving, the propeller shaft (but not the rear wheels) at all times. Sensors linking the engine’s ECU and the anti-lock brakes, meanwhile, constantly monitor and anticipate wheel slippage.

Located just ahead of the rear final drive is an electronically-controlled coupling (Fig.2) which enables drive to be fed through both front and rear axles. Its main clutch is connected to the propeller shaft, while a control clutch connects to the rear drive

The control clutch features a cam system comprising two plates with asymmetric grooves on both faces, separated by a series of ball bearings. In order to activate rear-wheel drive, the control clutch is engaged by an electromagnet and this causes one of the plates to be slowed down, causing the ball bearings to move to one end of the grooves. This forces the plates to separate which in turn applies pressure to the main clutch, and torque is transmitted between the two to give rear-wheel drive (Figs. 3 and 4). The main clutch transmits torque relative to the current applied to the electromagnet and the resulting engagement pressure.

The instant ALL MODE anticipates wheel slippage when encountering unexpected slippery conditions on-road, such as mud, wet leaves or ice, the coupling is automatically activated and drive is correctly apportioned, the maximum torque split being 53/47 front-to-rear. A torque-limiter prevents excessive torque being sent to the rear wheels.

If conditions become trickier, or the Murano is being used off-road, the system can be switched to Lock, which permanently locks the chassis into four-wheel drive mode. In this condition, the control unit supplies the maximum amount of current to the electromagnet (Fig.5). This causes the control clutch cam plates to apply maximum pressure to the main clutch to give a 53/47 split in transmitted drive, and this is available up to a speed of approximately 18 mph (US and Canadian MO after 2005 to 6 mph). Over this speed, the system reverts to Auto operation, switching back to Lock when the Murano is slowed.

ALL MODE offers further sophistication during everyday driving (Fig. 6). Under light acceleration the electromagnetic clutch is engaged by up to 50%, dividing the torque to suit the conditions. During hard acceleration, the unit is fully engaged (100%) to allow the maximum permissible front/rear torque split of 53/47.
And when the Murano is being driven at fairly constant speeds, a small drag current is supplied to the electromagnet to ensure that the system is ready to act instantaneously.

Finally, when the ABS is operated, the coupling is de-energised so that the front and rear axles can be controlled individually.
As a four-wheel drive vehicle, Murano has a strong active safety story, starting with the elevated driving position which provides a better vantage point allowing the driver to be more aware of his or her surroundings.

The ALL MODE electronic four-wheel drive system not only provides drive to all four wheels, but sensors constantly monitor available grip to ensure safe progress at all times. A standard feature on Murano is the electronic stability programme, ESP+, which either brakes individual wheels or redistributes engine torque to regain stability if traction is lost, as well as reducing the unwanted effects of excess understeer or oversteer. (In US and Canadian MO it's option of Dynamic Control Package and it's called VDC)"

I think that also US MO has 53:47 torque split (not like in manual 50:50) and there is always small amount of torque on rear wheels for faster reaction like in euro MO. They didn't mention about any change in AWD in European MO but they mention that they've changed CVT computer program. I think it equals that they hadn't change it (AWD). Only one difference in European AWD is that Lock MODE is still to 18mph but AWD switch operates like in 2005> US MO. (I have driven European MO at my Poland service/dealer)
More>: http://www.nissanpress.co.uk/nissan/...7292murano.htm

[teonek]

Fig.1: Schematic of the Murano’s ALL MODE system

[teonek]

Fig 2: The ALL MODE system’s electronically-controlled coupling

[teonek]

Fig.3: The electronically-controlled coupling operating in two-wheel drive. The unit’s clutch is not engaged at this point.

[teonek]

Fig. 4: The electromagnetic clutch is activated and torque is transmitted to the rear wheels.

[teonek]

Fig. 5: When ALL MODE is switched to ‘Lock’, maximum current is supplied to the electromagnet. This results in maximum pressure to the main clutch to give a 53/47 front/rear split in transmitted drive.

[teonek]

Fig. 6: This diagram shows the engagement of the electromagnetic clutch unit under a variety of conditions. 100 % indicates that maximum torque split is taking place, ie 53% front and 47% rear.

[Eric L.]

Great post. I'm making it a sticky. Thanks for finding the info!

[Drewtoo]

Originally posted by Eric L.
Great post. I'm making it a sticky. Thanks for finding the info!

One quick question though:

Is it OK to drive the vehicle over 18 MPH in the lock mode?

e.g. I am driving up to Tahoe in the snow on I80 and it starts to get slippery, I slow to 25 MPH, not stopping and then flip the switch from AUTO AWD to LOCK and then continue to vary my speeds from say 25 -45 MPH. Will this screw up the tranny? i.e. do I need to keep it below 18 MPH?

Also, what if one forget it's in lock, the snow clears up and I you’re doing 75 MPH all of a sudden again?

Perhaps this is a stupid question to some, but after owning an ‘82 Toyota truck; there were definitely no no's with regard to going too fast when using 4 wheel drive, even when in the 4 wheel high gear.

Cheers!

[Eric L.]

Originally posted by Drewtoo


One quick question though:

Is it OK to drive the vehicle over 18 MPH in the lock mode?

e.g. I am driving up to Tahoe in the snow on I80 and it starts to get slippery, I slow to 25 MPH, not stopping and then flip the switch from AUTO AWD to LOCK and then continue to vary my speeds from say 25 -45 MPH. Will this screw up the tranny? i.e. do I need to keep it below 18 MPH?

Also, what if one forget it's in lock, the snow clears up and I you’re doing 75 MPH all of a sudden again?

Perhaps this is a stupid question to some, but after owning an ‘82 Toyota truck; there were definitely no no's with regard to going too fast when using 4 wheel drive, even when in the 4 wheel high gear.

Cheers!

Nope, it won't damage your drivetrain. Above 18mph, it switches back to AUTO mode, even though the light on the dash still says AWD LOCK. Once your speed drops below 18mph, it actually locks the AWD 50/50 F/R. That said, its probably not a great idea to use AWD Lock unless its REALLY slippery out there, since you'll wear out the AWD unnecessarily.

[Drewtoo]

Originally posted by Eric L.


Nope, it won't damage your drivetrain. Above 18mph, it switches back to AUTO mode, even though the light on the dash still says AWD LOCK. Once your speed drops below 18mph, it actually locks the AWD 50/50 F/R. That said, its probably not a great idea to use AWD Lock unless its REALLY slippery out there, since you'll wear out the AWD unnecessarily.

Great, appreciate the reassurance. I'm never one to assume too much. Especially after paying $35K for my new AWD SL.


BTW: Just bought the ’07 AWD SL Black on Latte w/the touring package, including: NAV, XM, Dynamic Stability Control, Traction Control and the tire pressure monitor. Thus far I must say, of all the things I like about the vehicle, the back up camera is so damn cool. Especially at night. MPG kind of sucks @ 17.5, but then, I don’t exactly drive it like a Honda or Lexus driver would.

[Eric L.]

Originally posted by Drewtoo


Great, appreciate the reassurance. I'm never one to assume too much. Especially after paying $35K for my new AWD SL.


BTW: Just bought the ’07 AWD SL Black on Latte w/the touring package, including: NAV, XM, Dynamic Stability Control, Traction Control and the tire pressure monitor. Thus far I must say, of all the things I like about the vehicle, the back up camera is so damn cool. Especially at night. MPG kind of sucks @ 17.5, but then, I don’t exactly drive it like a Honda or Lexus driver would.

Congrats, and smart choice getting the stability control.

[hfelknor]

Drewtoo and Eric...........
The AWD LOCK on that 2007 switches to "AUTO" mode above SIX mph, not 18.



Homer

[Eric L.]

Originally posted by hfelknor
Drewtoo and Eric...........
The AWD LOCK on that 2007 switches to "AUTO" mode above SIX mph, not 18.



Homer

I guess I assumed he had a 2003-4 since he mentioned 18mph. I admit I like the fact that my MO has AWD lock up to 18mph, rather than 6mph, and am keeping my fingers crossed the AWD system holds up under my normal usage.

[teonek]

I've also read somewhere (when I search info about MO AWD) that on 2005>2007 50/50 is to 6 mph and it is slowly engaging/disengaging from/to 18 mph. I think that the biggest difference between 2003-04 and 05-07 AWD control unit could be their softer engaging not only in LOCK but also in AUTO.