1990 Toyota Corolla

Engine Mechanical problem
1990 Toyota Corolla 4 cyl Front Wheel Drive Automatic 200, 00 miles

my check engine light has come on and I have no idea where to begin. I've checked the basic radiator fluid, oil, belts. Which all are ok. Would the check engine light come on if my transmission fluid is low?
My financial situation prevents me from going to my mechanic which charges $90.0 per hour just for his time doing the diognostic and mechanical work, the parts of course will be another cost which I do not have. Thank you for you consideration on this matter.
March 10, 2008.

There is a small gray connector in the engine compartment labeled " diagnostics".
Get a small paper clip and bend to a " U" shape and connect it to TE-1 or T to E-1 slots in the diag. Connector. Turn engine to on (do not start), the check engine light will flash all the codes e.G. Flash, flash. Pause. Flash is code 21.
The connector is usually on the strut tower on the drivers side.

Mar 16, 2008.