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Check Engine Light On

  1. Turn ignition off. Remove and inspect ECU fuse and HAZARD fuse (main fuse box), and No. 14 fuse (under-dash fuse box). Inspect ground connections at thermostat housing or Brown/Black and Black/Red wires at connector located on right front strut tower.
  2. Turn ignition on. Verify that CHECK ENGINE light stays on for 2 seconds. If light does not stay on for 2 seconds, check connections or loose wires at main relay, ECU fuse or No. 14 fuse. If CHECK ENGINE light comes on, check ECU LED inspection light for codes. If codes are present, repair trouble code(s). If no code(s) are present or if LED does not flash, go to next step.
  3. Start engine. If engine does not start go to step 4). If engine starts, turn ignition off. Disconnect ECU connector "B". Turn ignition on. Verify if CHECK ENGINE light is on. If light is on, repair short to ground in Green/Orange wire between ECU terminal B6 and combination meter. If light did not turn on, substitute a known good ECU and recheck. If condition is corrected, replace original ECU.
  4. If engine does not start, turn ignition on. Disconnect 3-wire connectors (one at a time) at MAP sensor, throttle angle sensor, and EGR valve lift sensor (HF and Calif. A/T). 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 5).
  5. 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 6).
  6. Turn ignition off. Connect ECU Test Harness to ECU main harness side only. See Figure . Check continuity between ground and terminals C13 and C15. If continuity is present, repair short in Yellow/Red wire between ECU and MAP sensor, or in Yellow/White wire between ECU and PA sensor, throttle angle sensor or EGR valve lift sensor. If continuity is not present, go to step 7).
  7. Reconnect 3-wire connectors removed from sensors. Connect ECU Test Harness connectors "A", "B", and "C" to ECU. See Figure . Turn ignition on. Measure voltage between ground and ECU terminals A16 and A18. If less than one volt is present, go to step 8). If more than 1 volt is present, repair open in wire between ECU terminals A16 and A18 and thermostat housing (ground).
  8. Measure voltage between ECU terminals A13, A15 (positive) and A18 (negative). If battery voltage is present, substitute a known good ECU and recheck. If condition is corrected, replace original ECU. If battery voltage is not present, repair open in Yellow/Black wire between ECU terminals A13 and A15 and main relay. Check main relay and connectors.
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