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"Check Engine" Light On

  1. Turn ignition off. Remove fuse No. 1 and No. 11 (main fuse box), and fuse No. 1 (under-dash fuse box) for at least 10 seconds to reset ECU. Replace blown fuse(s), if any.
  2. Turn ignition on. If "CHECK ENGINE" light stays on after 2 seconds, go to step 3). If light turns off after 2 seconds, problem is intermittent. Check for poor connections or loose wires at fuses No. 1 and No. 11 (main fuse box), fuse No. 1 (under-dash fuse box), main relay, and ground.
  3. Check for trouble code(s) at ECU LED inspection light. Repair trouble code(s) if present. If no trouble code(s) is present, try to start engine. If engine starts, go to step 4). If engine does not start, go to step 5).
  4. If engine starts, turn ignition off. Disconnect connector "B" from ECU. Turn ignition on. If "CHECK ENGINE" light is on, repair short to ground in Green/Red wire between ECU and warning light. If light did not come on, substitute a known good ECU and retest. If condition is rectified, replace original ECU.
  5. If engine does not start, disconnect 3-wire connector (one at a time) at MAP sensor, throttle angle sensor, and EGR valve lift sensor. If "CHECK ENGINE" light turns off while disconnecting connector from any of the sensors, replace that particular sensor. If light stayed on all the time, go to step 6).
  6. Reconnect all sensor connectors. Disconnect 3-wire connector to Atmospheric Pressure (PA) sensor. Check if LED is flashing Code 13. If Code 13 is present, replace PA sensor. If Code 13 is not present, go to step 7).
  7. Turn ignition off. Connect ECU test harness connector "C" to ECU main harness side. Check continuity between terminal C13 to ground and terminal C15 to ground. If continuity is present, go to next step. If continuity is not present, go to step 9).
  8. Disconnect connectors C17 and C93 located at left front strut tower. If continuity is now present, repair short between ECU terminal C15 and MAP sensor, or short between ECU terminal C13 and C17. If continuity is not present, repair short between C93 connector and throttle angle sensor or EGR valve lift sensor.
  9. Reconnect ECU test harness connector "C" to ECU side. Turn ignition on. Measure voltage individually between terminals A16 and A18 to ground. If voltage is less than one volt, go to step 10). If not, repair individual ground connection between ECU and ECU ground located on intake manifold near No. 1 injector.
  10. Measure voltage between ECU terminals A15 (pos.) and A18 (neg.). If battery voltage is present, substitute a known good ECU and recheck. If condition is rectified, replace original ECU. If battery voltage was not present, repair open in Yellow/Black wire between ECU terminal A15 and main relay. Check main relay wiring and connectors.
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