I completed the VSC-off mod on my T4R. The cool thing about this mod is the ATRAC is still active.
A great thank-you to Andries at T120. This is his hard work not mine.
In 2wd dash lights are on (VSC & Diff lock). I didn't mess around enough to decide if VSC is working, traction control IS working; I'm assuming it has full VSC. It has all the familiar noises and accompanying reduction in power. The system seems to get confused if you attempt to change from 2HI to 4HI with the switch on. Lights get stuck in flash mode.
In 4HI it works as advertised You have an [i][u]unlocked Torsen center diff and no interference from the VSC; the VSC and Diff Lock light are on. You can definitely feel/hear ATRAC doing it's thing. The same deal in 4LO... I can lock and unlock the diff while in 4HI (or 4LO) with my switch on. It locks & unlocks ok. When unlocked the diff lock light continues to flash even after the diff unlocks. It is not a perfect mod. It beats the heck out what Toyota gave from the factory. I am thrilled!
My advice is to not do a mode change with the added VSC switch on (grounding the wire). I may retract/amend that as I learn more. For now I plan to lock and unlock the diff, switch 4HI to 4LO with my added VSC switch in the off (ungrounded or open) position.
The bottom line is it's a great mod that facilitates the use of 4HI and 4LO without VSC interference and the center diff unlocked.
Andries saved me thousands! I was having serious 'VSC-off' envy of the 2008 guys!
This is the original Andries, aka Bulldog, thread: http://www.toyota120.com/forum/showthread.php?t=3817 Below are some ‘how-to’ pics.
Take care to make sure the wire doesn't contact the very warm heater core coolant piping.