“AWD off” message on long drive

[SHOdded]

If you have a PP, then the PTU has a temp sensor.  Otherwise there are no sensors in the AWD system itself.

Have not heard of tread design causing problems unless the AWD is in action continuously for a long period of time. Traction differences are handled by AdvanceTrac dividing the speed and power as appropriate.

It is possible that a hub problem has developed, but even then I have not seen such a message go off.  Does the ptu fluid look good?  Then we are back to tire pressures or 4x4 module or damaged wiring/dirty connectors.

[jus2quik]

So no heat sensors or electronic sensors  in the rdu unit itself,right? Clutch engagement is manual not electronically actuated? I don’t have a PP car.

[SHOdded]

Clutch actuation is electronically actuated.  The 4x4 module tells the RDU when and how much clutch to apply.

But no sensors otherwise in the RDU, no.  There is supposed to be a heat protection mode for the RDU, but I am fuzzy on how it actually works.  Probably related to the solenoid in the ATC that controls the clutch.

Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the active torque control coupling (ATCC) solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATCC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.

[ZSHO]

Has the AWD OFF in Dash returned! If not wouldn't worry to much IMO!

The Powertrain Control Module sends a signal to partially or fully engage or disengage the Rear Wheel Drive part of the AWD. Based on input from the (four wheel sensors) feeding the ABS module, the steering-angle sensor module, and the instrument cluster module, the PCM sends a signal to the AWD really module and the 4x4 lock solenoid in the Active Torque Coupling.  Z

[jus2quik]

Signal came one once about 4 hours into a trip and about 3 hours on the way home my wife said,she is about to take the car on a 1 month trek across the country with a friend next month and don't want her to have any issues .we do normal 1 or two hour round trip drives and never had an issue. I'm gonna put some new tires on it before her trip ,I'm sure it will be fine.From what I'm reading the tires don't have to be so precisely the same size to matter .

[jims2015]

Has the AWD OFF in Dash returned! If not wouldn't worry to much IMO!

The Powertrain Control Module sends a signal to partially or fully engage or disengage the Rear Wheel Drive part of the AWD. Based on input from the (four wheel sensors) feeding the ABS module, the steering-angle sensor module, and the instrument cluster module, the PCM sends a signal to the AWD really module and the 4x4 lock solenoid in the Active Torque Coupling.  Z

What do you mean by partially engage? Does the clutch in the unit actually partially slip under certain conditions? I thought it was either on or off.

[ZSHO]

Has the AWD OFF in Dash returned! If not wouldn't worry to much IMO!

The Powertrain Control Module sends a signal to partially or fully engage or disengage the Rear Wheel Drive part of the AWD. Based on input from the (four wheel sensors) feeding the ABS module, the steering-angle sensor module, and the instrument cluster module, the PCM sends a signal to the AWD really module and the 4x4 lock solenoid in the Active Torque Coupling.  Z

What do you mean by partially engage? Does the clutch in the unit actually partially slip under certain conditions? I thought it was either on or off.

The ATC in turn is controlled by the PCM. The amount of torque is infinitely variable, not just engaged-ON and disengaged-OFF.
It can deliver zero percent to the rear, like it does in the Default FWD condition. Or it can deliver anywhere from 1 percent to 100 percent of the engine torque to the rear wheels IIRC!  Z

[SHOdded]

If you are worried about it and don't need AWD, pull the fuse for the trip.  Will not hurt anything, but definitely avoid hard acceleration from a stop to avoid torque steer.

[avidmotion]

https://shoforum.com/index.php?threads/haldex-awd-system.107563/

[avidmotion]

and this....
https://shoforum.com/index.php?threads/how-does-the-awd-work.119781/

[avidmotion]

wow after reading all that I think I am all researched up on the subject now!

[jims2015]

Has the AWD OFF in Dash returned! If not wouldn't worry to much IMO!

The Powertrain Control Module sends a signal to partially or fully engage or disengage the Rear Wheel Drive part of the AWD. Based on input from the (four wheel sensors) feeding the ABS module, the steering-angle sensor module, and the instrument cluster module, the PCM sends a signal to the AWD really module and the 4x4 lock solenoid in the Active Torque Coupling.  Z

What do you mean by partially engage? Does the clutch in the unit actually partially slip under certain conditions? I thought it was either on or off.

The ATC in turn is controlled by the PCM. The amount of torque is infinitely variable, not just engaged-ON and disengaged-OFF.
It can deliver zero percent to the rear, like it does in the Default FWD condition. Or it can deliver anywhere from 1 percent to 100 percent of the engine torque to the rear wheels IIRC!  Z

So otherwords, the clutches can take quite an abuse while slipping under load. I haven't heard of any failures. Are the clutches wet or dry?

[SHOdded]

They are immersed in Mercon LV so I would say wet.

[jus2quik]

I thought the PP models were wet clutches and the standard was a dry clutch setup

[ZSHO]

Good INFO on the AWD & MORE! Z

The Rear Differential Unit on the police version uses a fluid-filled clutch pack, while the retail version uses dry clutches. The fluid-filled RDU can withstand more severe duty.

Both the PI Sedan and PI Utility operate as FWD vehicles until wheel slip is detected. Only then does power transfer to the rear wheels. Of the most importance, the transaxle with water-cooled (police-only) AWD Power Transfer Unit was located. And then the rear axle mounted Active Torque Coupling Unit attached to the Rear Differential Unit was pointed out. On these AWD vehicles, power is continually fed to both the front half-shafts and the rear driveshaft. The driveshaft is constantly engaged and rotating even if power is not fed to the rear wheels.

The Front Wheel Drive system and the Power Transfer Unit send torque back to the rear clutch pack all the time. Any time the vehicle is moving, the driveshaft to the rear is turning. The Active Torque Coupling mounted on the Rear Differential Unit only passes on torque when needed. But it is literally right there when it is needed.

The ATC/RDU used on the Police Interceptors uses fluid-filled "wet" clutch packs. The retail Taurus and Explorer use dry clutches. The PI wet clutches can withstand higher temps and withstand higher temps longer than the retail unit. The ATC and RDU are not field serviceable. In case of a problem with either system, the whole unit is replaced.

http://www.hendonpub.com/resources/article_archive/results/details?id=5091