P2229

DTC P2229

CIRCUIT DESCRIPTION
The barometric pressure (BARO) sensor measures the pressure of the atmosphere. This pressure is affected by altitude and weather conditions. A diaphragm within the BARO sensor is displaced by the pressure changes that occur from varying altitudes and weather conditions. The sensor translates this action into electrical resistance. The BARO sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The BARO sensor provides a signal voltage to the ECM, relative to the pressure changes on the BARO sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Changes in BARO due to weather are relatively small, while changes due to altitude are significant. Pressure can range from 56 kPa at an altitude of 4,267 meters (14,000 feet), to 105 kPa at or below sea level. The BARO sensor has a range of 8-207 kPa. The ECM uses the BARO sensor input for fuel delivery and other diagnostics.

The ECM monitors the BARO sensor signal for pressure outside of the normal range. If the ECM detects a BARO sensor pressure that is excessively high, DTC P2229 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P2229 Barometric Pressure (BARO) Sensor Circuit High Voltage

CONDITIONS FOR RUNNING THE DTC
- The engine run time is more than 1 second.
- DTC P2229 runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The BARO is more than 110 kPa for 10 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.
- Clear the MIL and the DTC with a scan tool.

TEST DESCRIPTION

Steps 1-11:

Steps 12-15:

The numbers below refer to the step numbers on the diagnostic table.
4. A short to voltage on the 5-volt reference circuit will cause DTC P0653 to set.
7. This step tests the signal circuit of the BARO sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0653 to set.