GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0069: Manifold Absolute Pressure-Barometric Pressure Correlation

Diagnostic Fault Information

BARO Sensor

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

5-Volt Reference

P0107, P0452, P0522, P0532, P0641, P2228

P0069, P2228

P0069, P0533, P0641, P2229

P2227

BARO Sensor Signal

P0069, P2228

P0069, P2228

P0069, P2229

P2227

Low Reference

--

P0069, P2229

--

P2227

MAP Sensor

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

5-Volt Reference

P0107, P0452, P0522, P0532, P0641, P0807, P2228

P0069, P0106, P0107

P0107

P0107, P0452, P0522, P0532, P0641, P0807, P2228

P0106, P0107

MAP Sensor Signal

P0107

P0069, P0106, P0107

P0107

P0106, P0108, P0523, P0641

P0106, P0107, P1101

Low Reference

--

P0069, P0106, P0107

P0106, P0108, P1101

--

P0106, P0108

Typical Scan Tool Data

BARO Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Ignition ON

Parameter Normal Range: 64-103 kPa (Varies with altitude)

5-Volt Reference

0 kPa

0 kPa

128 kPa

BARO Sensor Signal

0 kPa

0 kPa

128 kPa

Low Reference

--

0 kPa

--

MAP Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine running, transmission in Park or Neutral

Parameter Normal Range: 20-48 kPa (Varies with altitude)

5-Volt Reference

10 kPa

10 kPa

104 kPa

MAP Sensor Signal

10 kPa

10 kPa

104 kPa

Low Reference

--

80-103 kPa

--

Circuit/System Description

The BARO sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The control module 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 control module on a signal circuit relative to the ambient pressure changes.

The manifold absolute pressure (MAP) sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The control module supplies 5 volts to the MAP sensor on a 5-volt reference circuit, and provides a ground on a low reference circuit. The MAP sensor provides a voltage signal to the control module on a signal circuit relative to the intake manifold pressure changes. The control module compares the BARO sensor to the MAP sensor in order to monitor the BARO sensor operation.

Conditions for Running the DTC

    • DTCs P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0220, P0502, P0503, P2135, P2227, P2228, P2229 are not set.
    • The ignition is ON.

Conditions for Setting the DTC

    • The control module detects that the difference between the BARO sensor pressure and the MAP sensor pressure is more than 5 kPa when the ignition is ON before engine startup.
        OR
    • The difference between the BARO sensor pressure and the control module predicted BARO is more than 60 kPa when the engine is running.
    • The above conditions are met for 1 second.

Action Taken When the DTC Sets

DTC P0069 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0069 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Special Tools Reference

    • J 23738-A Mityvac
    • J 35555 Metal Mityvac

Circuit/System Verification

  1. Verify that DTCs P0106, P0107, P0108, P0641, P0651, P2227, P2228, or P2229 are not set.
  2. If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  3. Ignition ON, Engine OFF, determine the altitude for your area. Refer to Altitude Versus Barometric Pressure . Observe the MAP Sensor and BARO parameters. The readings should be within 5 kPa of each other and the Altitude Versus Barometric Pressure table.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the affected sensor.
  2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
  5. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  6. Verify the scan tool sensor parameter is less than 12 kPa.
  7. If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the ECM.
  8. Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool sensor parameter is greater than 102 kPa for MAP and greater than 126 kPa for BARO.
  9. If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  10. If all circuits test normal, test or replace the affected sensor.

Component Testing

Skewed Sensor Test

  1. Ignition OFF, remove the vacuum source from the sensor.
  2. Ignition ON, observe and record the scan tool sensor pressure parameter. This is the first sensor reading.
  3. With the J 23738-A or J 35555 , apply 5 in Hg (17 kPa) of vacuum to the sensor. Observe and record the scan tool sensor pressure parameter. This is the second sensor reading.
  4. Subtract the second sensor reading from the first sensor reading. Verify that the vacuum decrease is within 1 in Hg (4 kPa) of the applied vacuum.
  5. If the vacuum decrease is not within the specified range, replace the sensor.
  6. With the J 23738-A or J 35555 , apply 10 in Hg (34 kPa) of vacuum to the sensor. Observe and record the scan tool sensor pressure parameter. This is the third sensor reading.
  7. Subtract the third sensor reading from the first sensor reading. Verify that the vacuum decrease is within 1 in Hg (4 kPa) of the applied vacuum.
  8. If the vacuum decrease is not within the specified range, replace the sensor.

Erratic Signal Test

  1. Ignition OFF, remove the sensor.
  2. Install a 3A fused jumper wire between the 5-volt reference circuit terminal C and the corresponding terminal of the sensor.
  3. Install a jumper wire between the low reference circuit terminal A of the sensor and ground.
  4. Install a jumper wire at terminal B of the sensor.
  5. Connect a DMM between the jumper wire from terminal B of the sensor and ground.
  6. Ignition ON, with the J 23738-A or J 35555 , slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 volts without any spikes or dropouts.
  7. If the voltage reading is erratic, replace the sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for ECM replacement, setup, and programming.
    •  Barometric Pressure Sensor Replacement
    •  Manifold Absolute Pressure Sensor Replacement