Circuit Description
The barometric pressure (BARO) sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. This gives the powertrain control module (PCM) an indication of the current barometric pressure. The PCM 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 PCM supplies 5 volts to the BARO sensor on a 5-volt reference circuit, and provides a ground on a low reference circuit. The BARO sensor provides a voltage signal to the PCM on a signal circuit relative to the pressure changes. The PCM monitors the BARO sensor signal for voltage outside of the normal range. If the PCM detects a BARO sensor signal voltage 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 ignition is ON.
OR
The engine is cranking or running.
Conditions for Setting the DTC
The PCM detects that the BARO signal voltage is more than 4.5 volts for more than 8 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
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Is DTC P0641 set? | -- | Go to Step 3 | ||
3 | Observe the BARO parameter with a scan tool. Is the BARO parameter more than the specified value? | 4.5 V | Go to Step 5 | Go to Step 4 |
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections |
5 |
Important: The connectors for the following sensors are of the same configuration but are not interchangeable.
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 6 |
6 |
Is the BARO parameter less than the specified value? | 0.2 V | Go to Step 7 | Go to Step 8 |
7 |
Is the voltage more than the specified value? | 0.2 V | Go to Step 9 | Go to Step 10 |
8 | Test the BARO sensor signal circuit between the powertrain control module (PCM) and the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
9 | Test the low reference circuit between the PCM and the BARO sensor for high resistance or for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
10 | Test for an intermittent and for shorted terminals and for a poor connection at the BARO sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 |
11 | Test for an intermittent and for shorted terminals and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
12 | Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
