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Home >> Acura >> 1990 >> Legend Base, 4D Sedan, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Code 13: Atmospheric (Pa) Sensor
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Code 13: Atmospheric (Pa) Sensor

NOTE: For wiring diagrams, see WIRING DIAGRAMS article. For vacuum diagrams, see VACUUM DIAGRAMS article.
  1. Turn ignition off. Disconnect alternator sense fuse in under-hood relay box for 10 seconds to reset ECU. Start engine and observe CHECK ENGINE and Red LED lights. If lights are off, problem is intermittent. Check for poor or loose connections at PA sensor, Green/White, Yellow/White and Red wire terminals at connectors C403 and C312. Test drive and check again.
  2. If CHECK ENGINE light is on and Red LED indicates Code 13, turn ignition off. Connect ECU test harness between ECU and ECU connector. Turn ignition on. Measure voltage between ECU terminals C13 (positive) and C14 (negative). See Figure . If about 5 volts is indicated, go to step 3). If not, substitute a known ECU and recheck. If specified voltage in now available, replace original ECU.
  3. Measure voltage between terminals C9 (positive) and C14 (negative). If about 3 volts is not indicated, go to step 4). If about 3 volts is indicated, substitute a known good ECU and recheck. If condition goes away, replace original ECU.
  4. If about 5 volts was indicated instead of 3 volts, repair open in Red wire between ECU terminal C9 and PA sensor. If not, turn ignition off. Disconnect 3-pin PA sensor connector. Turn ignition on.
  5. Measure voltage between Yellow/White wire terminal and ground. If about 5 volts is present, go to next step. If not, repair open in Yellow/White wire between ECU terminal C13 and PA sensor.
  6. If about 5 volts is present from step 5), measure voltage between Yellow/White (positive) and Green/White (negative) wire terminals. If about 5 volts is present, go to step 7). If 5 volts is not present, repair open in Green/White wire between terminal C14 and sensor.
  7. Measure voltage between Red (positive) and Green/White (negative) wire terminals. If 5 volts is not present, repair short in Red wire between terminal C9 and PA sensor or replace ECU. If 5 volts is present, replace PA sensor.
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