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. The ECM compares the BARO sensor to the Boost sensor. This DTC will set if the difference between the two sensors is more than a predetermined amount.
Conditions for Running the DTC
| • | DTCs P0102, P0103, P0116, P0117, P0118, P0237, P0238, P0335, P0336, or P0500 is not set. |
| • | The engine speed is between 500-900 RPM. |
| • | The engine run time is more than 20 seconds. |
| • | The accelerator pedal angle is less than 60 percent. |
| • | The vehicle speed is less than 40 km/h (25 mph). |
| • | The mass air flow (MAF) is less than 50 g/sec. |
| • | The engine coolant temperature (ECT) is more than: |
| • | 80° C (176° F) for Federal Emissions systems. |
| • | or |
| • | 72° C (162° F) for California Emissions systems |
| • | The positive take off (PTO) is OFF. |
| • | The above conditions exist for 5 seconds. |
Conditions for Setting the DTC
| • | Federal: The difference between the BARO sensor and the Boost sensor is more than 30 kPa for 2 seconds. |
| or |
| • | California: The difference between the BARO sensor and the Boost sensor is more than 10 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. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the BARO sensors ability to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude. 103 kPa is the approximate barometric pressure (BARO) displayed at or near sea level.
-
This step tests for a sensor stuck in range .
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that any other DTCs are current? | -- | Go to Step 3 | |
3 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 4 |
Does the scan tool indicate that the pressure difference between the two vehicles is more than the specified value? | 5 kPa | Go to Step 7 | Go to Step 5 | |
Does the scan tool indicate the BARO sensor is operating normally? | -- | Go to Step 6 | Go to Step 7 | |
6 | Disconnect the hand vacuum pump from the sensor. Does the scan tool indicate that the BARO sensor pressure returns to the value observed in Step 4? | -- | Go to Intermittent Conditions | Go to Step 11 |
7 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 8 |
8 | Test the low reference circuit of the BARO sensor for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
9 | Inspect the BARO sensor for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
10 | Inspect the ECM for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
11 | Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
