gs400dave

Thanks Yamae.

edtbjon

The gremlin (i.e. Bosch box...) was located just in front of the front left door, about knee hight when you sit down in the car. There’s a panel which is easily removed, under which that box was installed. As Yamae points out this is not a standard Lexus part, but due to German law regulations it was installed by the German importers when the car arrived new to Germany in late -94 or early -95. Lexus had their own immobilizer solution with the next year model.
As far as I’ve figured it out, this particular box was only installed in Lexus (and Toyota) cars sold new in Germany in -94 and -95.
Even if this doesn’t sort your problem, at least you can rule this possibility out.