Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1995SUBURBAN K2500, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 121 (ENGINE CONTROLS - TESTS W/CODES - 2.2L)TROUBLE CODE CHARTSCODE 42, IGNITION CONTROLNOTES
1995 GMC Suburban K2500, 6.5 F
Code 42, Ignition Control: Notes
1995 GMC Suburban K2500, 6.5 FSECTION Notes
WARNING: This page is about a different car, the 1995 GMC Sonoma and 1995 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
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.
- This test confirms Code 42 and determines if fault is a hard failure or intermittent condition.
- This tests for a normal IC ground path through ignition module. If circuit is shorted to ground, reading will be less than 500 ohms.
- As test light voltage touches by-pass circuit, module should switch. Actual reading is not important as long as reading switches.
- 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.
- 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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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.