how to get transmission codes?

Question

Transmission is slipping real bad.

Answer 1

To gather the code for the transmission on this particular year. There was a flow of diagnosis that had to be performed. The transmission  fluid level and the condition has to be noted, A key on engine off (KOEO) test has to be performed and a ( KOER) Key on engine running has to be performed. If all that was given was PASS codes, you go by related symptoms. The ECM back then as it is today is to look for open circuit, short circuit grounds and rationality.