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  Topic Review (Newest First)
07-31-2018 09:53 AM
asakaze
Quote:
Originally Posted by CassieMariaa View Post
Is there a limit to how fast you can drive with the 4x4 lock? (For example, would you have to turn it off before entering a 55mph highway?)

Sent from my SM-N920V using Tapatalk
Since AWD Freedom Drive from DaimlerCrysler/Mitsubishi GS platform is shared among many vehicles, I'll drop this here from Dodge Caliber AWD service manual


--
Service manual
MODULE - FINAL DRIVE CONTROL

DESCRIPTION (ECC, Electronically-Controlled Coupling)


The ECC is controlled by it’s own controller that is located in the left kick panel area. It gets signals over the CAN bus from the ABS Wheel speed sensors and TPS signal.

OPERATION
The all-wheel-drive system requires no driver input or control. Under most driving conditions, it is passive and power is transmitted to the front wheels alone. Unlike all-wheel drive systems that rely on pumps or viscous fluids to transfer torque, this system requires no front-to-rear slippage for activation. This allows the system to transfer torque solely in response to accelerator pedal position. If the driver is asking for a lot of power, the system immediately starts clamping the electronically controlled coupling (ECC), transferring a high percentage of power to the rear wheels.

This avoids front wheel slippage, as power to propel the car is transmitted through all four tires. This mode of operation is called open-loop operation in that there is no feedback to affect the torque transfer. A second, closed loop, operating mode uses feedback from the wheel-speed sensors to determine the appropriate torque transfer. When the front wheels slip, the allwheel- drive electronic control module tells the ECC to start clamping, sending power to the rear wheels. Attempting the same aggressive launch described above with the front wheels on ice and the rear wheels on dry pavement, the ECC sends even more torque to the rear wheels to minimize slippage and launch the vehicle. Both modes are always active with the closed loop mode layered on top of open loop mode to increase torque to the rear wheels when needed to maintain traction in extreme cases.

Power to the rear wheels is modulated under the following conditions:
Slipping on ice while backing up will send a lot of power to the rear axle
Loss of traction while traveling at freeway speeds, for example hydroplaning on a puddle of water, will send very little power to the rear wheels because the controller knows at those speeds a lot of power is not needed at the rear wheels.


A third condition, which is independent of the others, uses wheel speed differences to determine when the vehicle is turning in a tight circle. This condition, which is indicated by a large
discrepancy in side-to-side wheel speeds, causes the electronic control module to reduce torque to the rear wheels to prevent binding in the driveline. The electronic control module is always checking for this condition as well. A fourth condition that is unique to the Caliber system is to influence vehicle dynamics. Other manufacturers limit AWD to aiding traction or providing off-road capability. They concentrate on launching the vehicle or going off road at speeds up to about 25 mph (40 km/hr).

Above that speed range, they use it to limit wheel slip for traction. On this system, additional ECM calibration controls torque to the rear wheels for improved handling in the 25-65 mph (40-105 km/hr) range. In this speed range, the system increases torque to the rear wheels during cornering with the throttle open to make the car turn more easily – make the handling more neutral. This is more readily accomplished with an electronically controlled system, than with viscous-coupling or gerotor systems that require some degree of front-to-rear slip to transfer torque to the rear wheels. Above 70 mph (113 km/hr), the control strategy provides minimal torque to the rear wheels under normal driving conditions to aid fuel economy. The ECC system is easier to calibrate, more flexible and more precise than viscouscoupling, Torsen, or gerotor system, but less costly. It is also less costly than the systems used in luxury cars from other manufacturers while providing similar functionality.

The electronic control module also interfaces with the ESP and traction control systems. The interface allows the ESP system to use the ECC to help gain control of the vehicle. For this purpose, torque transmitted to the rear wheels by the ECC can be reduced. The Caliber AWD system is not traction control. It only works on situations where front-to-rear traction varies, for instance, front wheels on ice, rear wheels on dry pavement or climbing steep grades. AWD does not aid side-to-side traction. ESP does that through brake intervention on this system.
07-27-2018 03:00 PM
CassieMariaa Is there a limit to how fast you can drive with the 4x4 lock? (For example, would you have to turn it off before entering a 55mph highway?)

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11-09-2016 04:39 PM
tripplec They aspect of using the Lock ON. Is the drive system engages power for traction to the rear right at the start of movement. There is no waiting for a slip or spin to occur before a computer engages the rear for further traction. As for percentages etc I don't know and not seen it documented. The action may have changed over the years of this design from mine (2009) to the new builds. I doubt even the dealer techs know unless they're a real 4x4 person and looked into it. Guessing by reps is common and hate that. They should fess up and say they don't know exactly or contact JEEP for the facts which is rarely done.
11-02-2016 05:00 PM
zoner99 jeep.ca/en/4x4basics/systemwork
10-29-2016 06:18 AM
Stringplucker Pulling the lever locks the center diff, meaning you have 50/50 of power transferred to both axles. Normal means that it's a higher percentage to the front wheels, with rear wheels at a much lower percentage...I think I read 30%, with remaining at the front.
10-28-2016 02:44 PM
Neil
4WD Indicator / Lock Question

Hi,
I got my Jeep Compass North last night. It was snowing so I wanted to make sure the 4 wheel drive was on. So I pulled the chrome lever and 4WD showed up on the dash. But later I read in the owner's manual that this setting is "4WD lock" and it implied that 4WD is always on, even when it doesn't say 4WD on the dash? Or am I confusing this? Will 4WD come on as needed without lifting that chrome lever thingy?
Thanks,
Neil

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