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Code 65 - Barometric Pressure Switch

  1. Make sure that the barometric pressure switch connector is mated correctly with wiring harness connector. If not, reconnect and repeat "Functional Test".
  2. Determine local altitude. Below 3500 ft., switch is normally open. Above 4000 ft., switch is normally closed. Do not test switch at altitudes between 3500 and 4000 ft. as switch may be in either condition. Disconnect wiring harness from switch. Connect an ohmmeter across switch terminals.
  3. If resistance is greater than 10 ohms at altitudes above 4000 ft. or less than 1000 ohms below 3500 ft., replace switch and repeat functional test. If resistance is less than 10 ohms at altitudes above 4000 ft. or more than 1000 ohms below 3500 ft., proceed with test.
  4. Disconnect harness plug from MCU. Check wires leading from MCU pins 14 and 18 to switch for continuity. If resistance of either wire is less than 10 ohms replace MCU. If resistance is over 10 ohms in either wire, repair open circuit. Repeat "Functional Test".
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