Letsride

The ecu will not have anything to do with the dash lights not coming on. If it was the immobilizer the security light would blink. Start checking all of your connections and fuses before doing anything else.

Mauser

What are the numbers on your IC900 chip? 93c56? If so it can be revirginized. I have been able to revirginize the eeprom on my 1998 lx470. I also have successfully made preprogrammed eeproms with the virgin program on them. I have found that the ecu part number needs to be the same for the ecu to work. There is no vin or mileage info written to the ecu.

It isnt as simple to revirginize the ecu on years 1998-2003 as it is on later years, but can be done.

EZCarKeys

Onizuka, it sounds like your getting errored information and the locksmith that tried to help is limited in his capabilities. PM me if you're still stuck on this vehicle and I'll do what I can to help.

TW99GS300

If you are able to power on with the old ECU but not the new ECU then it's likely the ECU is faulty.
However, that would be a very unlikely case as the ignition fuse circuit is independent of the ECU's EFI Fused power.
The ignition switch tells the ECU to turn on, not the other way around. So even if no ECU is plugged in, all other accesories will still actually turn on.

I have played with many ECU options for the 2GS.

Even JDM GE ECUs can be plugged in and start the car, pre 2000 JDM is only 4 speed auto vs post 2000 is 5 speed.
2000 with the same plugs will work with pre-00 vehicles.
late 2000 with different style plugs obviously will not.

Your options are as follow.
If your original ECU works, have someone that works with SMD to move the IC900 over from the other ecu or purchase a virginized IC900.
Find another locksmith that can read the IC900 and program a transponder to match.
Find another ECU with key pair. I have one from a '00 with the master transponder chip pair if you're interested.