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Home >> Honda >> 1990 >> Accord DX, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Trouble Codes - PGM-FI >> Code 3 - Map Sensor
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Code 3 - Map Sensor

  1. Turn ignition off. Remove BACK-UP fuse in the under-hood relay box for 10 seconds to reset ECU. Start engine and warm to normal operating temperature (cooling fan on). Verify if CHECK ENGINE light is on and if LED is flashing Code 3. If LED is flashing Code 3, go to next step. If LED is not flashing Code 3, problem is intermittent. Check connectors at MAP sensor and at ECU.
  2. Turn ignition off. Disconnect 3-wire connector from MAP sensor. Turn ignition on. Measure voltage between Red/White (positive) and negative Green (negative) terminals. If reading is about 5 volts, go to step 3). If reading is not about 5 volts, repair open in Red/White wire between ECU terminal D19 and MAP sensor. If wire is okay, substitute a known good ECU. If condition is corrected, replace original ECU.
  3. Measure voltage between Red/White (positive) and Blue/White (negative) terminals. If about 5 volts are present, go to step 4). If about 5 volts is not present, repair open in Blue/White wire between ECU terminal D21 and MAP sensor. If wire is okay, substitute a known good ECU. If condition is corrected, replace original ECU.
  4. Measure voltage between White/Blue (positive) and Blue/White (negative) terminals. If voltage is about 5 volts, go to step 5). If about 5 volts are not present, repair open in White/Blue wire between ECU terminal D17 and MAP sensor. If wire is okay, substitute a known good ECU. If condition is corrected, replace original ECU.
  5. Turn ignition off. Reconnect 3-wire connector to MAP sensor. Connect ECU Test Harness between ECU and ECU harness. Refer to Fig. Figure . Turn ignition on. Measure voltage between terminal positive D17 and negative D21. If reading is not about 3 volts, replace MAP sensor.
  6. If there is about 3 volts present, substitute a known good ECU and recheck. If condition is corrected, replace original ECU.
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