Diagnostic Aids

Check for poor connections or damaged harness. Monitor scan tester status for gear selector switch while wiggling harness.F

Fig 1: Code 31, Schematic, Park/Neutral Switch Circuit 3.8L

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 31, Flow Chart, Park/Neutral Switch Circuit 3.8L

Courtesy of GENERAL MOTORS CORP.