2nd Gen - Direct control over TC shifting
Posted: Fri Feb 20, 2015 3:20 pm
I have always believed that the myriad of safety systems which Nissan incorporates into allowing me to shift my T-case is a vulnerability for those times when I will need 4X4 the most. The thought of knocking out a wheel speed sensor wire by a hidden branch during a water crossing and losing the ability to shift my TC just does not sit well with me. This did not happen, but ABS issues did come up about a month before I had to have a functioning 4X4 system. I designed and implemented a system which allows me to shift the TC directly on my input whenever I wished.
What I gained:
Control and a piece of mind
A certain sense of accomplishment that comes along with overcoming a challenge
What I lost:
All safety systems associated with shifting the TC – you can really mess things up if you don’t know what you are doing
Other people can’t walk up to my truck and shift the TC without my instructions
Going back to stock would be difficult
Shift on the fly – I have my own safety protocol now
Hill Descent Control – never used the feature
4WD malfunction light
What resale value?
What I did:
Took over all inputs to the TC computer and made the truck think is in 2WD at all times.
Took over the control of the 4x4 selector switch to rotate the TC motor using existing wiring and shift relays.
Took over the 4x4 cluster indicator light to tell me which mode I am in.
Took over the Hill Descent Control (HDC) switch as a safety switch.
Added my own relay/transistor logic which uses input from the four encoder lines in the shift motor assembly to control the cluster indicator as the motor is rotating
How it works:
While driving around, my 4WD selector switch is in 4HI position (I call this neutral). As long as the HDC switch is ‘OFF’ the 4WD selector does not do anything.
When I am in 2WD and want to go to 4HI or 4LO or in 4HI and want to go to 4LO – these are all Clockwise movements of the shift motor – I stop, put the truck in Neutral (I am automatic) step on the brake so that I am not moving (this is my own safety protocol – it does not need to be performed but since I took out any and all safeties I insist on it), turn ‘ON’ the HDC button, and turn the 4WD selector switch from 4HI to 4LO – the motor does it’s thing and when I am in the desired position as indicated by the 4x4 cluster light I return the 4WD selector to its 4HI (neutral) position and turn ‘OFF’ the HDC switch.
Shifting from 4LO to 4HI or 2WD or from 4HI to 2WD – these are counter clockwise movements of the shift motor – the process is basically the same except I turn the 4WD selector switch from 4HI to 2WD.
I have had this for two months now and have used it extensively. It has not let me down in any way. The circuit can be expanded for additional safety features etc. but I just wanted it done.
Here is the link to the circuit if you want to have a look under the covers…
https://drive.google.com/file/d/0B6ozDg ... sp=sharing
What I gained:
Control and a piece of mind
A certain sense of accomplishment that comes along with overcoming a challenge
What I lost:
All safety systems associated with shifting the TC – you can really mess things up if you don’t know what you are doing
Other people can’t walk up to my truck and shift the TC without my instructions
Going back to stock would be difficult
Shift on the fly – I have my own safety protocol now
Hill Descent Control – never used the feature
4WD malfunction light
What resale value?
What I did:
Took over all inputs to the TC computer and made the truck think is in 2WD at all times.
Took over the control of the 4x4 selector switch to rotate the TC motor using existing wiring and shift relays.
Took over the 4x4 cluster indicator light to tell me which mode I am in.
Took over the Hill Descent Control (HDC) switch as a safety switch.
Added my own relay/transistor logic which uses input from the four encoder lines in the shift motor assembly to control the cluster indicator as the motor is rotating
How it works:
While driving around, my 4WD selector switch is in 4HI position (I call this neutral). As long as the HDC switch is ‘OFF’ the 4WD selector does not do anything.
When I am in 2WD and want to go to 4HI or 4LO or in 4HI and want to go to 4LO – these are all Clockwise movements of the shift motor – I stop, put the truck in Neutral (I am automatic) step on the brake so that I am not moving (this is my own safety protocol – it does not need to be performed but since I took out any and all safeties I insist on it), turn ‘ON’ the HDC button, and turn the 4WD selector switch from 4HI to 4LO – the motor does it’s thing and when I am in the desired position as indicated by the 4x4 cluster light I return the 4WD selector to its 4HI (neutral) position and turn ‘OFF’ the HDC switch.
Shifting from 4LO to 4HI or 2WD or from 4HI to 2WD – these are counter clockwise movements of the shift motor – the process is basically the same except I turn the 4WD selector switch from 4HI to 2WD.
I have had this for two months now and have used it extensively. It has not let me down in any way. The circuit can be expanded for additional safety features etc. but I just wanted it done.
Here is the link to the circuit if you want to have a look under the covers…
https://drive.google.com/file/d/0B6ozDg ... sp=sharing