P0108

CIRCUIT DESCRIPTION
The Barometric Pressure Sensor (BARO) responds to changes in altitude and atmospheric conditions. This gives the Engine Control Module (ECM) an indication of barometric pressure. The ECM uses this information to calculate fuel delivery. The BARO sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The ECM supplies 5 volts to the BARO sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The BARO sensor provides a signal to the ECM on a signal circuit relative to the pressure changes. The ECM monitors the BARO sensor signal for voltage outside of the normal range. If the ECM detects a BARO sensor signal voltage that is excessively high, this Diagnostic Trouble Code (DTC) will set.

CONDITIONS FOR RUNNING THE DTC
The diagnostic runs continuously.

CONDITIONS FOR SETTING THE DTC
The barometric pressure is more than 104 kPa for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION

Steps 1-11:

The numbers below refer to the step numbers on the diagnostic table.
3. This step determines if the fault is actually on the 5-volt reference circuit or if the fault is from a short to battery voltage backfeeding from the signal circuit of the BARO sensor.
7. This step inspects the ECM and the electrical connector for possible bent pins or any unwanted circuit to circuit contact.