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.
1998 GMC Forward Control 7.4 BFACTORY OEM SERVICE PROCEDURE
Ignition Coil Test
- Turn ignition off. Remove engine cover. Disconnect distributor lead and wiring from ignition coil.
- Place DVOM on high scale. Connect DVOM as shown in step 1 of illustration. See Fig 1. If reading is not infinite, replace ignition coil.
- Place DVOM on low scale. Connect DVOM as shown in step 2 of illustration. See Fig 2. If reading is not 0.1 ohm, replace ignition coil.
- Place DVOM on high scale. Connect DVOM as shown in step 3 of illustration. See Fig 3. If reading is not 5000-25,000 ohms, replace ignition coil.
- Reconnect distributor lead and wiring to ignition coil. Install engine cover.
Factory Service Tools
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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.
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