A quick method to see which trouble code or codes are being set in your cars ECM is to jumper the A and B pins of the 12 pin ALDL OBD1 connector with a paper clip which is the last 2 pins on upper row at right end.
While the car is off, sitting still, turn the ignition key forward while this jumper is in place.
Do not start the car. The Service Engine Soon ( SES ) light will flash in a repeating sequence, telling which trouble codes have been set in the ECM.
A service manual for your year car will have a chart outlining what each trouble code stands for, or posts in this OBD-I can be of help.

This paper clip method will tell you the trouble code or codes set in your ECM, but it will not tell you what conditions the trouble code is being set under, or let you clear the trouble codes on the fly, as the ALDL cable used with a Ease scanner can

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True Custom Performance Tuning