Start here:
http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx Very few diagnostic errors on mid 90's and earlier Toyotas will present a constant CEL/MIL... always check for error codes.If the light doesn't come on when the key is turned to the "ON" position, BEFORE the car is started, it's either burned out or the owner removed the light to try and hide or ignore problems.
EDIT: and I have NO idea what "tickover speed" means... perhaps you could explain without the use of slang or region specific colloquialisms.