Is your Scanguage reading the actual ECU command or is it simply indicating the PWM dutycycle %..?

Electromagnetic actuators that are controlled used PWM voltages often have a "keep-alive" minimum pulse duty cycle to overcome the "striction" effect often present in these devices, especially if hydraulic control of some kind is involved. Many systems even "dither" the PWM dutycycle at a low frequency rate, low enough frequency to allow the device to remain in a constant "vibratory" motion.

 

Back in '09 when I first looked into this, I used a scope to monitor the actual PWM signal output from the 4WD module. This was before I got a SG-II which reads the 4WD PID PWM signal. On the scope, it did go to zero. Comparing the scope to the SG-II, it showed about 50% of the SG-II reading. Desert Dog rethought his coding which was based on 100% max which it can't be to prevent drivetrain wind up, wheel hop, etc. He modified the coding then to reflect the change based on 50% being max.

 

Take an actual 4WD, R/awd, and have it in full, 100%, locked mode ONLY for/during low speed acceleration, straight-forward (or even slight turns) acceleration, and you will not experience wheel hop at all and not enough driveline windup to seriously degrade drive line component life cycles. Maybe some slight tire scrubbing.

The problem arises from running it fully locked on a tractive surface continuously.

So I see no problem in the use of 100% lockup, 50/50 F/R torque split under these restrictions. And keep in mind that the SH-AWD system goes into 50/50, or even 30/70, F/R torque split under these same conditions via the ~7% over-driving of the rear.

I suspect the only true way to determine the F/R torque split under varying throttle conditions is on a 4-wheel dyno.

 

Well, of course but most of the time it's driven on hard dry pavement and that's what I was refering to.

A function test right from the Ford manual is for the tech to command 100% rear wheel torque and make hard low speed turns. If it resists turning, it's working properly.

 

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