It might be tough for your brother to follow your advice. There is no OBD port in the 1993 Toyota Corolla. However, there is a Diagnostic box in the engine bay next to the left-hand side strut tower.

If your brother pops the hood, he should see a small black box labeled Diagnostic which does the same thing a modern OBD-II port does. Since it’s connected to the vehicle’s computer, you can scan it for trouble codes to help you diagnose any problems early on.

To scan the ‘93 Corolla for trouble codes, you’ll need to short it—do this by untangling a paper clip, and inserting one end into the TE1 port and the other end into the E1 port. Turn the ignition to the ON position without starting the engine.

Now, sit in the car. The Check Engine Light will begin flashing in a coded manner. For example, three flashes in quick succession, followed by a pause, and then five flashes in quick succession, followed by a long pause—this tells you the trouble code is 35. Consult your owner’s manual to see what this trouble code indicates.

If this is all too much trouble, your brother can take his Corolla to a Toyota dealership, where techs will be able to accurately scan for trouble codes, diagnose the problem, and fix it.

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