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Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 20 other vehicles, including the 1994 GMC Yukon, 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Suburban, and 1994 GMC Rally Camper Special. 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 appropriate TESTS W/O CODES article in this section. See below.

Fig 1: Code 42 Schematic ("C" & "K" Series Exc. 5.7L M/T) Ignition Control
G93I76420
Fig 2: Code 42 Schematic ("C" & "K" Series 5.7L M/T) Ignition Control
G94A66019
Fig 3: Code 42 Schematic ("P" Series A/T) Ignition Control
G94D66020
Fig 4: Code 42 Schematic ("G" Series) Ignition Control
G94E66021
Fig 5: Code 42 Schematic ("P" Series M/T) Ignition Control
G94F66022
Fig 6: Code 42 Flow Chart Ignition Control
G94J66026
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