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 4WD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE
Engine Controls - System/Component Tests
- Introduction
- Computerized Engine Controls
- Engine Sensors & Switches
- Air Charge Temperature (Act) Sensor
- Barometric Pressure Sensor
- Clutch Switch
- Crankshaft Position Sensor (Cps)
- Engine Coolant Temperature (ECT) Sensor
- EGR Valve Position (EVP) Sensor
- Heated Gas Oxygen (HEGO) Sensor
- Inertia Switch
- Knock Sensor (Bronco II & Ranger 2.9L)
- Manifold Absolute Pressure (Map) Sensor
- Mass Airflow (Ma) Sensor
- Neutral Drive Switch (NDS) & Clutch Switch
- Power Steering Pressure Switch (PSPS)
- Throttle Position Sensor
- Vane Air(Flow) Temperature (Vat) Sensor
- Vane Airflow Meter
- Vehicle Speed Sensor (VSS)
- Relay Checks
- Solenoid Checks
- Module Checks
- Fuel System Checks
- Fuel Control Checks
- Idle Control System
- Ignition System
- Air Injection Systems
- Air Supply Pump
- Air Silencer/Filter (Air Pump And Pulse Air Inlet)
- Air By-Pass Valve (Normally Closed)
- Air Check Valve
- Air Supply Control Valve
- Air Control Valve (Switch-Relief)
- Air Pump Resonator
- Combination Air By-Pass/Air Control Valve
- Dual THERMACTOR Air Control Solenoid Valve
- Electrical Vacuum Control Valve
- Pulse Air Valve
- Solenoid Vacuum Valve Assembly
- THERMACTOR Idle Vacuum (TIV) Valve
- Vacuum Control Valve (VCV)
- Vacuum Check Valve
- Vacuum Reservoir
- Exhaust Gas RECIRCULATION Systems
- Fuel Evaporation Systems
- PCV Valve
- Thermostatic Air Cleaner
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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