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HOMESERVICE MANUALSCHEVROLET1995FORWARD CONTROL 7.4 NREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 7.4LTROUBLE CODE CHARTSCODE 42, IGNITION CONTROLNOTES
1995 Chevrolet Forward Control 7.4 N

Code 42, Ignition Control: Notes

1995 Chevrolet Forward Control 7.4 NSECTION Notes

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.
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