*DISCLAIMER* I don't have an FJ Cruiser yet and haven't tried these hacks myself. I need volunteers to try them and report how they work.
1- Using A-TRAC with rear locker engaged:
According to the wiring diagram for the 2007 FJC it looks like A-TRAC can be used with the rear locker engaged by disconnecting the signal wire betwen the Transfer Indicator Switch on the rear differential and the Skid Control ECU. There is a possiblility that it could set a code C1248 (open circuit in rear differential lock) in the VSC system but the DTC detecting condition seems unlikely in normal 4-wheeling situations: "At vehicle speed of 31mph or more, 3 seconds elapse after rear differential changes from free to lock".
The easiest place to disconnect this circuit looks to be at connector LA2, pin 11 in the left kick panel. It will be a light blue/yellow wire in a white, 11-pin connector. If this hack works like I hope it will, the ABS and VSC OFF warning lights won't illuminate when the rear diff lock and the A-TRAC switches are both turned on and the slip indicator light will only blink when the A-TRAC system is controlling wheelspin.
2- Adding A-TRAC to your FJ Cruiser:
It is as simple as buying the $60 A-TRAC switch from your friendly Toyota dealer and installing to the existing connector behind the switch panel. All of the hardware is already there, it is the same stuff used with the regular TRAC that comes on every FJ Cruiser. I am sure it will work on the ones with the rear locker but not certain about the base models without the locker as the TRAC ECU has different part numbers shown with locker and without; A-TRAC is not offered as a factory option without the rear locker. If you are not sure about spending the money you can also install a single pole momentary switch to the pink/green and black/white wires at pins 3 & 4 of the Active Trac control switch connector, a flat 4-pin connector that should be taped to the harness behind the switch panel.
Who will be first?
5/19/2006 update
An update with corrected information on the A-TRAC+rear locker hack.
I incorrectly assumed the Skid Control ECU supplied the signal voltage to the diff lock position switch, and then to ground. The signal voltage actually comes through the rear diff lock indicator LED in the combination meter, reaching ground at the diff lock position switch. The Skid Control ECU simply reads the 12v or 0v signal. No reference voltage is supplied by the Skid ECU to the light blue/yellow wire.
There are several ways of making this work, the key is to disconnect the Skid Control ECU from the rear diff indicator LED/switch circuit and supply battery voltage to the Skid Control ECU at connector A5, pin 1 when the ignition is on.
A possible way of making this work is to disconnect the light blue/yellow wire at connector LA2 and put a jumper wire at the Skid Control ECU (master cylinder and pump) between connector A4, pin 26 (light blue/yellow wire) and Connector A5, pin 1 (black/orange wire) to supply the 12v signal with the key on.
07-13-2006 update:
You cannot add A-TRAC to an FJ Cruiser that did not come from the factory with the locking rear differential. See posts by PRCruiser and gunther here:
http://www.fjcruiserforums.com/forum...854#post114854
INSTALL THE ATRAC SWITCH
USING ATRAC AND LOCKER AT THE SAME TIME
