Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.

The scan tester cannot help diagnose a Code 42 problem. See INTERMITTENTS in TESTS W/O CODES article in this section.

Fig 1: Code 42, Schematic, Electronic Spark Timing

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 42, Schematic, Electronic Spark Timing (4.3L)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Code 42, Flow Chart, Electronic Spark Timing

Courtesy of GENERAL MOTORS CORP.