1990 Ford Bronco II RWD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

When making measurements on a wiring harness, both a visual inspection and a continuity test should be performed. Inspect terminal connector pins for damage and corrosion, when directed to remove a connector.

  • Spark timing adjustments are not possible. Timing is controlled by the EDIS module with input from the ECA.
  • When checking voltage drop to GROUND, circuit must have a voltage drop of less than one volt.
  • Battery voltage (VBAT) is any voltage reading within 2 volts of actual battery voltage.
  • Spark timing will vary at idle due to feedback spark strategy used to control idle speed.
  • DO NOT connect positive lead of EDIS diagnostic cable to battery or connect cable to VR sensor until directed to.
  • SAW and IDM signal detectors in EDIS diagnostic cable will not work unless diagnostic cable battery leads are connected to battery.
  • When using DVOM to measure DC voltage always connect positive lead to BOB terminal A(+) and negative lead to A(-).
CAUTION: DO NOT use a 12-volt incandescent (high voltage) test light to test circuit signals, as it will load the circuit and may cause incorrect measurements or faulty EDIS/ECA operations (engine stall).
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:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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