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 MANUALSFORD1988BRONCO 4.9 Y, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMDECELERATION CONTROL SYSTEMTESTINGVACUUM SENSING SWITCH TEST
1988 Ford Bronco 4.9 Y, Automatic
Vacuum Sensing Switch Test
1988 Ford Bronco 4.9 Y, AutomaticSECTION Vacuum Sensing Switch Test
- On models with vacuum sensing switch, check continuity between terminals while applying vacuum of less than 19.4 in. Hg.
- If switch shows continuity (switch closed), replace switch. If not, apply more than 20.6 in. Hg vacuum to switch and recheck continuity. If no continuity is present, replace switch.
NOTE:
Between 19.4 and 20.6 in. Hg, switch may be either open or closed.
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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.