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Code 5, Map Sensor

  1. Turn ignition off. Remove clock fuse in the under-hood relay box for 10 seconds to reset ECU. Start engine and observe PGM-FI warning light. If light is off, problem is intermittent. Test drive and check again.
  2. If light is on, turn ignition off. Using a "T" fitting, connect a handheld vacuum pump/gauge into vacuum hose between throttle body and MAP sensor. Start engine. If vacuum is not present, repair as necessary. If vacuum is present and holds, turn ignition off.
  3. Connect inspection harness between MAP sensor and harness. Turn ignition on. Measure voltage between White (pos.) terminal and Green (neg.) terminal. If reading is not about 3 volts, replace MAP sensor. If voltage reading is about 3 volts, substitute a known good ECU. If condition is rectified, replace original ECU.
  4. If voltage reading from ground to Red/White wire of coolant sensor harness was not about 5 volts in step 3), turn ignition off. Connect system checker harness between ECU and ECU connector. Turn ignition on. Measure voltage between terminals C6 (pos.) and C12 (neg.). If about 5 volts is present, repair open in Red/White wire between ECU terminal C6 and coolant sensor.
  5. If voltage reading is not about 5 volts, disconnect "C" connector from main wiring harness only, not at ECU. Measure voltage between terminals C6 (pos.) and C12 (neg.). If about 5 volts is now indicated, repair short in Red/White wire between ECU terminal C6 and sensor.
  6. If about 5 volts is not indicated, substitute a known good ECU. If condition is rectified, replace original ECU.
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