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Code 3: Map Sensor

  1. Turn ignition off. Remove BACK-UP fuse (10-amp) from underhood fuse/relay box for 10 seconds to reset ECM. Start engine, and let it idle. Check ECM for fault codes. If Code 3 is not present, problem is intermittent. Check for poor or loose connections at MAP sensor and ECM connectors. Test drive vehicle and retest.
  2. If Code 3 is present, turn ignition off. Disconnect 3-pin MAP sensor connector. Turn ignition on. Measure voltage between MAP sensor Yellow/White wire (+) and body ground. See Fig 1 . If voltage is about 5 volts, go to step 4). If voltage is not about 5 volts, connect connector "D" of ECM Test Harness (07LAJ-PT3010A ) to ECM, leaving vehicle wiring harness disconnected.
    Fig 1: Locating MAP Sensor & Identifying Connector Terminals
    G92F26208Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. Turn ignition on. Measure voltage between test terminals D19 (+) and D21 (-). If about 5 volts are present, repair open circuit in D19 (Yellow/White wire) between ECM connector and MAP sensor. If voltage is not about 5 volts, replace ECM and retest.
  4. If voltage is about 5 volts in step 2), measure voltage between Yellow/White (+) and Green/White (-) wires at MAP sensor. If voltage is not about 5 volts, repair open in Green/White wire between ECM terminal D21 and MAP sensor. If voltage is about 5 volts, measure voltage between White/Blue (+) and Green/White (-) wire terminals at MAP sensor.
  5. If voltage is about 5 volts, go to step 7). If voltage is not about 5 volts, turn ignition off. On A/T models, disconnect Transmission Control Module (TCM) 22-pin connector. Turn ignition on. If about 5 volts are now present, replace TCM. If about 5 volts are still not present, turn ignition off. Go to next step.
  6. On all models, connect ECM Test Harness (07LAJ-PT3010A ) connector "D" only to ECM, leaving vehicle wiring harness disconnected. Measure voltage between test harness terminals D17 and D21. If about 5 volts are present, repair open or short in circuit D17 (White/Blue wire) between TCM (A/T), ECM and MAP sensor. If voltage is not about 5 volts, replace ECM and retest.
  7. Turn ignition off. Reconnect 3-pin MAP sensor connector. Connect ECM Test Harness (07LAJ-PT3010A ) between ECM and ECM connectors. See Figure . Turn ignition on. Measure voltage between test terminals D17 and D21. If voltage is not about 3 volts, replace MAP sensor. If about 3 volts are present, replace ECM and retest.
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