CODE 42, IGNITION CONTROL - ALL MODELS Chevrolet Chevy Van G3500

CODE 42, IGNITION CONTROL - ALL MODELS

Code 42 indicates control module has seen an open or short to ground in Ignition Control (IC) or by-pass circuits.

Note. Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 42 and determines if fault is a hard failure or intermittent condition.
2. This tests for a normal IC ground path through ignition module. If circuit is shorted to ground, reading will be less than 500 ohms.
3. As test light voltage touches by-pass circuit, module should switch. This causes ohmmeter to "over-range" with meter in 100-200 ohm range. A higher ohm range will indicate over 5000 ohms. This test assures module switched.
4. If module did not switch, this step tests for a short in IC circuit, an open in by-pass circuit and a faulty ignition module connection or module.
5. This step confirms Code 42 is a faulty control module and not an intermittent problem in IC and by-pass circuits.

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

Code 42 Schematic ("C", "K" & "P" Series) Ignition Control. Scheme 92

Code 42 Schematic ("G", "L" & "M", "S" & "T" Series) Ignition Control. Scheme 93

Code 42 Flow Chart (All Models) Ignition Control. Scheme 94