On vehicles older than 1996, you might need to follow a different procedure. Every manufacturer before that time had their own way of storing and presenting fault codes. The upside is that these vehicles often don’t require that you hook up a scanner to retrieve codes. Check your service manual for the procedure for your vehicle. You might find this video on how to pull codes from a Honda or Acura without a scanner helpful. Consult the service manual for specifics on the vehicle you're working on.