1992 Acura Legend Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Code 3: Map Sensor

  1. Turn ignition off. Remove fuse No. 15 (ACG) from underdash fuse box for 10 seconds to reset ECU. Start engine, and connect jumper wire to self-diagnostic connector. Observe CHECK ENGINE light. If Code 3 is not present, problem is intermittent. Check for poor or loose connection at MAP sensor connector. Test drive vehicle and retest.
  2. If Code 3 is present, turn ignition off. Disconnect 3-wire connector at MAP sensor. Turn ignition on. Measure voltage between Yellow/White (+) terminal and body ground. If reading is about 5 volts, go to step 4). If reading is not about 5 volts, turn ignition off. Connect "D" connector of ECU Test Harness (07LAJ-PT3010A ) to ECU, leaving vehicle wiring harness disconnected.
    Fig 1: MAP Sensor Connector Terminal ID
    G92E26207Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. Turn ignition on. If voltage is about 5 volts, repair open in Yellow/White wire between ECU terminal D19 and MAP sensor. If reading is not about 5 volts, turn ignition off. If voltage is not about 5 volts, substitute a known good ECU, and recheck. If voltage is now correct, replace original ECU.
  4. If voltage is about 5 volts in step 2), measure voltage between Yellow/White and Green/White wires at MAP sensor. See Fig 1 . If voltage is not about 5 volts, repair open in Green/White wire between ECU connector terminal D21 and MAP sensor. If voltage is about 5 volts, measure voltage between Red (+) and Green/White (-) terminal at MAP sensor.
  5. If reading is not about 5 volts, check for open or short in circuit D17 (Red wire) between ECU connector and MAP sensor. If circuit is okay, substitute a known good ECU. If condition goes away, replace original ECU. If voltage is about 5 volts, turn ignition off. Reconnect MAP sensor connector. Connect ECU Test Harness (07LAJ-PT3010A ) between ECU and ECU connector. See Figure .
  6. 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, substitute a known good ECU. If condition goes away, replace original ECU.
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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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