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.
1990 Ford Bronco II RWD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE
Functional Test
- With ignition switch off, connect a 12-volt test light between glow plug module test terminal and ground. See Figure. Position test light so that it can be seen from driver's seat. Turn ignition switch to ON position and monitor test light. Compare test light times to chart. See Fig 1. Total test light ON time includes time from the beginning of the initial ON cycle to the end of the last ON-OFF cycle measured in seconds.
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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