Circuit Description
The barometric pressure (BARO) sensor responds to changes in altitude and atmospheric conditions. This gives the engine control module (ECM) an indication of BARO. 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 a 5-volt reference circuit, and provides a ground on a low reference circuit. The BARO sensor provides a voltage signal to the ECM on a signal circuit relative to the atmospheric pressure changes. The ECM monitors the BARO sensor signal for a voltage outside of the normal range. If the ECM detects the actual BARO sensor signal is not within a predetermined range of the calculated BARO sensor value, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2227 Barometric Pressure (BARO) Sensor Performance
Conditions for Running the DTC
| • | Before the ECM can report DTC P2227 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P0338, P2228, and P2229 must run and pass. |
| • | The engine is operating for more than 20 seconds. |
| • | The mass air flow (MAF) is more than 11 grams per second. |
| • | The difference between the calculated manifold absolute pressure (MAP) and BARO pressure is less than 1.0 kPa for more than 3 seconds. |
| • | DTC P2227 runs continuously once the above conditions are met for 2 seconds. |
Conditions for Setting the DTC
| • | The ECM detects that the BARO pressure changed more than 5 kPa within 20 seconds. |
| OR |
| • | The ECM detects that the BARO pressure changed more than 30 kPa since the last ignition cycle. |
| • | The conditions exist for at least 4 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 4 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. |
Diagnostic Aids
The following table illustrates the ECM connector locations:
ECM Connector Location | |
|---|---|
C2 | C1 |
Front of Vehicle | |
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if a condition exists.
-
This step is testing the signal circuit. The signal circuit is pulled up to a voltage, so the scan tool should display a voltage within the specified range. If the voltage is low, this indicates the signal circuit is grounded.
-
This step is testing the signal circuit. The signal circuit is pulled up to a voltage. The scan tool should display 0.00 volts when the signal circuit is grounded to the ECM housing with a fused jumper wire. If the voltage displayed on the scan tool is more than the specified value, test the signal circuit of the BARO sensor for an open or a high resistance.
-
The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the BARO sensor. If the amperage on the 5-volt reference circuit is less than the specified value, test the 5-volt reference circuit for an open, a high resistance.
-
This step tests for a high resistance in the low reference circuit of the BARO sensor. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse, or the PCM/ETC fuse, allows the ECM to completely power down.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Step 4 | |
3 | Is DTC P2228 or P2229 also set? | -- | Go to Step 7 | |
4 |
Does the BARO parameter remain steady and not change by more than the specified value while a related connector is being moved? | 3 kPa | Go to Step 5 | Go to Step 17 |
5 | Observe the BARO sensor parameter on a scan tool while moving the related wiring harnesses. Does the BARO parameter remain steady and not change by more than the specified value while a related wiring harness is being moved? | 3 kPa | Go to Step 6 | Go to Step 18 |
6 |
Did the DTC fail this ignition? | -- | Go to Step 7 | Go to Diagnostic Aids |
|
Important: The signal circuit of the BARO sensor is pulled up to a voltage through a 1 mega-ohm resistor.
Is the voltage within the specified range? | 4.9-5.2 V | Go to Step 8 | Go to Step 12 | |
Is the voltage at the specified value? | 0.00 V | Go to Step 9 | Go to Step 13 | |
Is the amperage more than the specified value? | 80 mA | Go to Step 10 | Go to Step 11 | |
Notice: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw. Is the resistance more than the specified value? | 5 ohms | Go to Step 14 | Go to Step 15 | |
11 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
12 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
13 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
14 | Test the low reference circuit of the BARO sensor for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
15 | Test for an intermittent 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 21 | Go to Step 19 |
16 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 |
17 | Repair the damaged connectors and terminals. Refer to Connector Repairs . Did you complete the repair? | -- | Go to Step 21 | -- |
18 | Repair the affected circuit as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 21 | -- |
19 | Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- |
20 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 21 | -- |
21 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 22 |
22 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
