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Code 9 (Atmospheric Pressure Sensor)

  1. Check for poor connections at atmospheric pressure sensor connector. Repair or replace as necessary. If connections are okay, check for battery voltage at terminal "A" of atmospheric pressure sensor connector.
  2. If voltage is not present, check for open circuit in wiring harness from main relay to atmospheric pressure sensor. If voltage is present, measure voltage at terminal "D" of atmospheric pressure sensor connector.
  3. If reading is 4.5-5.5 volts, go to next step. If not, check for short circuit in wiring harness from terminal "D" of atmospheric pressure sensor to ECU connector.
  4. Measure voltage at terminal "2H" of ECU. If reading is more than 4.9 volts, check for open circuit in ground harness. Also check for open circuit in wiring harness from terminal "B" of atmospheric pressure sensor to terminal "2H" of ECU connector.
  5. If reading is less than 1.4 volts, check for short circuit in wiring harness connected to atmospheric pressure sensor. Also check for open circuit in wiring harness from terminal "D" of atmospheric pressure sensor to terminal "2A" of ECU connector. If reading is between 1.4-4.9 volts, replace faulty ECU.
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