Quick Test: Preparation

1988 Ford Bronco 4.9 Y, Standard, M5OD-R2SECTION Preparation

Before hooking up any equipment to diagnose the EEC system, make the following checks:

  • Verify condition of air cleaner and air ducting.
  • Check all vacuum hoses for leaks, restrictions, and proper routing.
  • Check the EEC-IV system wiring harness electrical connections for corrosion, bent or broken pins, loose wires or terminals, and proper routing.
  • Check the ECA, sensors and actuators for physical damage.
  • Perform all necessary safety precautions to prevent personal injury or vehicle damage.
  • Set parking brake and place shift lever in "P" for automatic transmissions, and Neutral for manual transmissions. DO NOT  move shift lever during testing unless specifically directed to do so.
  • Turn off all lights and accessories. Ensure vehicle doors are closed when making voltage or resistance readings.
  • Check engine coolant level.
  • Start engine and idle until upper radiator hose is hot and pressurized, and throttle is off fast idle. Check for leaks around exhaust manifold, exhaust gas oxygen sensor, and vacuum hose connections.
  • Turn ignition key off. Service items as required, then go to EQUIPMENT HOOK-UP  .

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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.