I'm posting this this one time only... I will be deleting this thread in the morning so read up and take notes. (and, of course, if your preferences are setup to email you when replies are posted you'll get all of this in your email)
FIRST! Look here:
http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=122
System delete:
1) REMOVE the Theft Deterrent Computer.
2) Now ground the blue wire with orange stripe (Pin 13).
3) Install good aftermarket alarm.
4) DONE.
System reset (the sure way). Do this AT the deterrent ECU's connector with the battery, theft deterrent ECU and all fuses installed correctly:
1) Jumper the violet with yellow stripe wire (pin 3) to ground.
2) Jumper the blue wire with red stripe (pin 10) to ground.
3) Disconnect both and start vehicle. If it does not start after this test for a ground signal at the starter relay's coil while the ignition is held at STA. If no ground is present either the wiring or deterrent ECU are damaged. If there is then the security system is not to blame.