1988 Ford Bronco II 4WD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE

Test Procedure

  1. Turn ignition switch to "OFF" position. Make sure all procedures of covered under PREPARATION  as well as those under EQUIPMENT HOOK-UP  have been followed. Engine should be at normal operating temperature.
  2. Ensure VOM or tester is connected properly. Turn ignition on. If Star Tester is being used latch center button in down position at this time.
  3. The ECA will run through a test cycle, opening and closing various solenoids and switches. After the completion of the test cycle the codes will appear. Record all codes.
    NOTE: On all vehicles equipped with a 4.9L engine and manual transmission, the clutch pedal must be depressed during the KOEO SELF-TEST.
  4. The first set of codes to appear are the KOEO SELF-TEST codes, they will be repeated twice, followed by the Separator Pulse signal and then the CONTINUOUS MEMORY codes. These codes will also be repeated twice.
  5. A KOEO code 11 indicates the system has passed the self test. A code 11 must be present before continuing. Disregard any CONTINUOUS MEMORY codes at this time. Service KOEO codes (in the order they appear) and rerun KOEO test until a code 11 is displayed. See KEY ON ENGINE OFF (KOEO) - TEST MENU  service code tables.
  6. Whenever a repair is made, repeat QUICK TEST  . If no codes are displayed, repeat SELF-TEST to verify that other service codes are still present.
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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