Converting from Command-trac to Selec-trac

[kjpilot]

I have the parts & I have a service manual, but this just brings up a queation. There is an electrical connector on both transfer cases, (they are identical, so the plug will work) the manual calls them position sensors. My question refers to the function of these sensors. Since the system is mechanical, I assume that this sensor is little more than the switch that turns on the "part-time" indicator light on the instrument cluster. My fear is that it is more, & I will need to do something with the engine computer.

Does anyone know the actual story? :-k

 

[Eddo]

I have the parts & I have a service manual, but this just brings up a queation. There is an electrical connector on both transfer cases, (they are identical, so the plug will work) the manual calls them position sensors. My question refers to the function of these sensors. Since the system is mechanical, I assume that this sensor is little more than the switch that turns on the "part-time" indicator light on the instrument cluster. My fear is that it is more, & I will need to do something with the engine computer.

Does anyone know the actual story? :-k

You are correct all the switch does is turn on the dash light. Nothing more.

However, I read somewhere that supposedly when shifted into 4-low the computer raises the idle RPM and adjusts timing for more low-end torque, raises ABS threshold, turns off part of ESP if applicable.

But either way, all the switch does is tell the computer/light what mode the t-case is in. As long as you have the position sensor for each case you should be fine. The select-trac switch has one more position setting over the command trac switch. At least I would assume so.

There where a few people on the lost board that have swapped t-cases.

 

[2003KJ]

However, I read somewhere that supposedly when shifted into 4-low the computer raises the idle RPM and adjusts timing for more low-end torque.

You are correct. And if you've got a manual ******, i believe when you shift into 4 lo, the computer also bypasses the clutch, which makes starting and stopping alot easier....i remember seeing that on the car and driver review of the KJ.

Swapping should be pretty straight forward....just like Eddo said, make sure you have the right connectors for the right t-case (meaning the one on the 231 now wouln't work on the 242.

 

[Eddo]

Actually, I was incorrect. Looks like it is actually the same sensor. Computer just interprets the Ohm reading a little different.

Select-Trac

SWITCH POS    OPERATING MODE       SENSOR RESISTANCE (ohms)
 1	          2WD                  1124-1243
 2	          4WD PART TIME        650-719
 3	          4WD FULL TIME        389-431
 4	          NEUTRAL              199-221
 5	          4WD LOW              57-64

Command-Trac

SWITCH POS    OPERATING MODE       SENSOR RESISTANCE (ohms)
 1	          2WD                  1124-1243
 2	          4WD PART TIME        650-719
 3	          NEUTRAL	           389-431
 4	          NEUTRAL              199-221
 5	          4WD LOW              57-64

So it looks like if you just swap out the command-trac for the select-trac the 4-Fulltime light will not work. Unless you flash the computer somehow to recognize the 389-431 Ohms as Full-time vs neutral.

However, If you don't care about the dash light I don't think it would make a difference.

 

[kjpilot]

SWEET! Thanks guys! icon996.gif