Diagnostic Aids

Normal "Scan" voltage varies between .1-1.0 volt, while in "closed loop". Code 13 sets in one minute, if voltage remains between .35-.55 volt, but the system will go into "open loop" in about 15 seconds. Verify a clean, tight ground connection for circuit No. 413. Open in circuits No. 412 or 413 will result in a Code 13. If Code 13 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.

Fig 1: Code 13, Circuit Wiring Diagram

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 13, Flow Chart

Courtesy of GENERAL MOTORS CORP.