Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 diaphragm action into the voltage signal input that is used by the engine control module (ECM) for diagnostics and emissions control.

The supercharger inlet absolute pressure (SCIP) sensor measures the absolute pressure of the air just after the throttle body, at the inlet of the supercharger. The plenum volume between the throttle body (TB) and the supercharger is where this sensor is located, and for the purpose of this diagnostic, this area is considered to be the intake manifold. The diaphragm within the SCIP sensor functions in the same manner as the BARO sensor. The sensors are not interchangeable.

The purpose of this diagnostic is to analyze the correlation between the BARO sensor, and the SCIP sensor. This is accomplished by continually comparing the difference between BARO and SCIP at key ON, engine OFF (KOEO), at closed throttle idle conditions, and at wide open throttle update events. At KOEO the difference between BARO and SCIP is represented on the scan tool by the SC Inlet Pressure parameter as a value that should be very close to zero. A negative SC Inlet Pressure parameter means that the BARO sensor value is less than the SCIP value. A positive SC Inlet Pressure parameter represents a BARO sensor value that is more than the SCIP value.

At idle the SC Inlet Pressure parameter represents the calculated difference between BARO and the reduced pressure that is present in the supercharger intake plenum as a positive value. At wide open throttle the SC Inlet Pressure parameter represents the calculated difference between BARO and the increased pressure that is present in the supercharger intake plenum, and should be very close to zero.

Both sensors have the following types of circuits:

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 4267 meters (14,000 feet), to 104 kPa at or below sea level.

If the ECM detects that the BARO sensor signal and the SCIP sensor signal are not within a calibrated range of each other, whether that value is negative or positive, DTC P0069 sets.

DTC P0069 is a Type B DTC.

DTC P0069 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools Required

J 35555 Metal Mityvac

1. Verify that DTCs P0106, P0107, P0108, P0641, P0651, P1182, P1183, P1184, or P2227, P2228, P2229 are not set.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Important: 

•	The harness connectors for the following sensors are the same configuration but are not interchangeable.

•	Review the engine controls schematics for the BARO sensor and for the SCIP sensor and note the circuit colors.

•	Inspect the wiring harness of the BARO sensor for the proper connections.

•	Inspect the wiring harness of the SCIP sensor for the proper connections.

2. Ignition ON, engine OFF, observe the scan tool SC Inlet Pressure and BARO parameters. Verify the SC Inlet Pressure and BARO sensor parameters are within 5 kPa of each other.
3. Ignition ON, observe the scan tool SC Inlet Pressure Sensor parameter. Start the engine, the SC Inlet Pressure Sensor parameter should decrease.
4. Verify the integrity of the SCIP and BARO sensors by inspecting for the following conditions:

•	Damaged components

•	Loose or improper installation

•	An air flow restriction

•	A cracked or restricted SCIP sensor vacuum hose

•	An intake manifold leak

1. Determine the altitude for your area. Refer to Altitude Versus Barometric Pressure .
2. Ignition ON, determine which sensor is out of range by comparing SC Inlet Pressure and BARO Sensor parameters with a scan tool. Both sensor values should be within 5 kPa of each other and the Altitude vs. Barometric Pressure table.
3. Ignition OFF, disconnect the harness connector at the affected sensor.
4. Ignition OFF, allow sufficient time for the control module to power down. Test for less than 5 ohms of resistance between the low reference circuit terminal and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

5. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground.

⇒	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.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

7. Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool sensor parameter is greater than 250 kPa.

⇒	If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

8. If all circuits test normal, test or replace the affected sensor.

Important: You must perform the Circuit/System Testing before proceeding with the Component Testing.

1. Turn ON the ignition with the engine OFF, and remove the affected sensor.
2. Install a 3A fused jumper wire between the 5-volt reference terminal of the sensor and 5-volt reference.
3. Install a jumper wire between the low reference terminal of the sensor and ground.
4. Install a jumper wire at the signal terminal sensor.
5. Connect a DMM between the jumper wire from terminal of the sensor and ground.
6. Install the J 35555 to the sensor vacuum port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 0-5.2 volts, without any spikes or dropouts.

⇒	If the voltage is not within the specified range or is erratic, replace the affected sensor.

Ignition ON, observe the scan tool MAP, SC Inlet Pressure, and BARO sensor parameters. The MAP, SC Inlet Pressure, and BARO sensor parameters should be within 5 kPa of each other.