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 low, DTC P2228 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2228 Barometric Pressure (BARO) Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | The engine run time is more than 1 second. |
| • | The ignition voltage is more than 7 volts. |
| • | DTC P2228 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The BARO is less than 40 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. |
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 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Does the scan tool indicate that DTC P0652 is also set? | -- | Go to DTC P0652 | Go to Step 3 | ||||||
3 | Observe the BARO parameter with a scan tool. Does the scan tool indicate that the pressure is less than the specified value? | 40 kPa | Go to Step 5 | Go to Step 4 | ||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||
5 |
Is the voltage more than the specified value? | 4.8 V | Go to Step 6 | Go to Step 7 | ||||||
6 | Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the BARO sensor and the signal circuit of the BARO sensor. Does the scan tool indicate that the BARO sensor pressure is more than the specified value? | 205 kPa | Go to Step 9 | Go to Step 8 | ||||||
7 | Test the 5-volt 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 | ||||||
8 | Test the signal circuit of the BARO sensor for the following:
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 for poor connections at the BARO sensor. 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 for poor connections at the engine control module (ECM). 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 Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||
