Code 3: Map Sensor
- Turn ignition off. Remove BACK-UP fuse (7.5-amp) from underhood fuse box for 10 seconds to reset ECM. Start engine, and allow it to 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. Test drive vehicle and retest.
- If Code 3 is present, turn ignition off. Disconnect 3-pin MAP sensor connector. Turn ignition on. Measure voltage between MAP sensor Yellow/Red or Yellow/White wire (positive) and any 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.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Turn ignition on. Measure voltage between test terminals D19 (+) and D21 (-). If about 5 volts are present, repair open circuit in D19 (Yellow/Red or Yellow/White wire) between ECM connector and MAP sensor. If voltage is not about 5 volts, replace ECM and retest.
- If voltage was about 5 volts in step 2), measure voltage between Yellow/Red or 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, check voltage between White/Yellow (+) and Green/White (-) wire terminals at MAP sensor.
- If voltage is about 5 volts, go to step 6). If voltage is not about 5 volts, measure voltage between test harness terminals D17 and D21. See Figure. If about 5 volts are present, repair open or short in circuit D17 (White/Yellow wire) between ECM connector and MAP sensor. If voltage is not about 5 volts, substitute a known good ECM and recheck. If voltage is about 5 volts, replace original ECM and retest. If voltage is not about 5 volts, replace MAP sensor.
- 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.