Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 1992 Oldsmobile Bravada, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Sonoma. 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.

Fig 1: Code 42 Schematic (2.5L) Electronic Spark Timing

Fig 2: Code 42 Schematic (All W/ 4L80-E Transmission) Electronic Spark Timing

Fig 3: Code 42 Schematic (3.1L) Electronic Spark Timing

Fig 4: Code 42 Schematic (All W/O 4L80-E Trans. Except 2.5L, 3.1L & 4.3L Turbo) Electronic Spark Timing

Fig 5: Code 42 Schematic (4.3L Turbo) Electronic Spark Timing

Fig 6: Code 42 Flow Chart Electronic Spark Timing