I'm trying to understand the functions of all pins and automatic 4wd.

I understand about every signals, but I am not sure about auto 4wd..
I know it modulates the clutch to apply 0% to 100% torque to the front transfer case, but how does it do it?!

Does it switch to 4HI and pull the motor a bit so it's in between 2HI and 4HI and the nearer to 4HI it transmits more torque? I'm not sure how it works, is there another mode on the T-Case that I don't understand?

IF you wonder why I ask, it's because I am thinking about making my own TCCM, it might not be necessary but it sounds interesting and it won't cost as much to do as a new one..

 

This is the way I am going to implement TCCM2, minus the automatic 4wd:

After car started:
- Test Encoder by unlocking TCase solenoid, moving the encoder to it's limits and validating encoder values (Parametrable: each and every time, ever other times etc..)
- Test Front wheel lock
- Verify that voltage values are within bounds.
- Verify internals

- Load last 4WD mode
- Get Encoder position
- If current position different than stored pos:
- Unlock TCase solenoid, move encoder to stored pos, Lock TCase solenoid, Lock/Unlock front wheels.

ON Auto4WD:
-TO DO-
- Flash Auto4WD Indicator Lamp.
- Lock Front Wheels, Validate Front Switch
- Verify Speed Sensors, Validate within bounds.
- PID Loop activated analog clutch according to speed sensors (? No Idea how to do it ?)
- Turn Auto4WD Indicator Lamp On. Others Off.

ON 2HI
- Flash 2HI Indicator Lamp.
- Unlock front wheels, validate front switch
- Unlock TCase solenoid, Move Actuator, Lock TCase solenoid.
- Turn 2HI Indicator Lamp On. Others Off.

ON 4HI
- Flash 4HI Indicator Lamp.
- Verify Speed Sensors, Validate within bounds.
- Lock Front Wheels, Validate Front Switch
- Unlock TCase solenoid, Move Actuator, Lock TCase solenoid.
- Turn 4HI Indicator Lamp On. Others Off.

ON 4LO
- Flash 4LO Indicator Lamp.
- Verify Neutral Drive or Speed Sensors within bounds.
- Lock Front Wheels, Validate Front Switch
- Unlock TCase solenoid, Move Actuator, Lock TCase solenoid.
- Turn 4LO Indicator Lamp On. Others Off.

ON Neutral
- Flash NeutralIndicator Lamp.
- Verify on Neutral Drive.
- Unlock TCase solenoid, Move Actuator, Lock TCase solenoid.
- Unlock Front Wheels, Validate Front Switch
- Turn NeutralIndicator Lamp On. Others Off.


These will be programmable:
- Speed vs Torque applied ratio in Auto4WD
- Auto4WD sensitivity
- 4HI Speed Limit
- Activate/DeActivate Auto4WD button
- When to do encoder tests (Every boot, every other time and so on)


Errors will probably be reported on the indicator lamps instead than on the VCM.

Other than that, it's simply a matter of activating a couple of H-Bridge drivers in PWM using a microcontroller like the ATMEGA32 or a parallax propeller or something like that..

I'm thinking of implementing redudency checks to prevent system faults and errors (like system trying to lock in 4LO by mistake for example)...


Any comments?
I really want someone to explain the Auto 4WD to me, it's where I am confused..

I also would like to find the mapping of the encoders for every gear selection.. It's simply a matter of getting the encoder values on a NV236 with a multimeter for each and every settings, if someone have this information, that would be great!!