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P0069



DTC P0069

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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
- Supercharger Inlet Pressure (SCIP) - Barometric Pressure (BARO) Correlation

Diagnostic Fault Information










Typical Scan Tool Data










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 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 (SCIAP) 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 SCIAP 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 SCIAP sensor. This is accomplished by continually comparing the difference between BARO and SCIAP 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 SCIAP 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 SCIAP value. A positive SC Inlet Pressure parameter represents a BARO sensor value that is more than the SCIAP 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:

* A ECM supplied and regulated 5-volt reference circuit
* A ECM supplied ground for the low reference circuit
* A sensor signal circuit that supplies a voltage input to the ECM

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 SCIAP sensor signal are not within a calibrated range of each other, whether that value is negative or positive, DTC P0069 sets.

Conditions for Running the DTC

* DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0120, P0121, P0128, P012B, P012C, P012D, P0220, P0502, P1516, P2101, P2227, P2228, P2229 are not set.
* The ignition is ON.
OR
* The engine is running.
* DTC P0069 runs continuously when the above conditions are met.

Conditions for Setting the DTC

* The ECM detects that during ignition ON, with the engine OFF, the calculated difference between BARO and SCIAP, whether that value is negative or positive, is more than 12 kPa for more than 30 seconds.
OR
* The ECM has detected that a wide open throttle update event has occurred within the previous 2 kilometers (1.2 miles) and the difference between BARO, and a calculated BARO using the SCIAP sensor, is more than 12 kPa for more than 30 seconds.
OR
* The ECM has not detected a wide open throttle update event within the previous 2 kilometers (1.2 miles) and the difference between BARO, and a calculated BARO using the SCIAP sensor, is more than 60 kPa for more than 30 seconds.

Action Taken When the DTC Sets

DTC P0069 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0069 is a Type B DTC.

Diagnostic Aids

* Any condition that can cause the BARO or SCIAP sensors to be shifted in value may cause this DTC to set.
* A slight to moderate resistance of 20-50 ohms on the 5-volt reference terminal C or the low reference circuit terminal A may cause this DTC to set.
* Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories in Diagnostic Aids. Component Tests and General Diagnostics

Circuit/System Verification

1. If DTCs P0107, P0108, P012B, P012C, P012D, P0641, P0651, or P2227, P2228, P2229 are also set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further information. Diagnostic Trouble Code Descriptions

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 SCIAP sensor and note the circuit colors.

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

* Inspect the wiring harness of the SCIAP sensor for the proper connections.

Important: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.

Ignition ON, observe the scan tool SC Inlet Pressure Sensor and BARO Sensor parameters. Verify the SC Inlet Pressure and BARO sensor parameters are within 5 kPa of each other.

2. Ignition ON, observe the scan tool SC Inlet Pressure Sensor kPa parameter. Start the engine. The SC Inlet Pressure Sensor kPa parameter should decrease.
3. Engine running, observe and record the SC Inlet Pressure Sensor parameter kPa value with a scan tool. The SC Inlet Pressure Sensor parameter should decrease.
4. Verify the integrity of the SCIAP and BARO sensors by inspecting for the following conditions:

* Damaged components
* Loose or improper installation
* An air flow restriction
* A cracked or restricted SCIAP sensor vacuum hose
* An intake manifold leak

Circuit/System Testing

1. Determine the altitude for your area. Refer to Altitude Versus Barometric Pressure. Both sensor values should be within 5 kPa of each other and the Altitude vs. Barometric Pressure table.
2. Ignition ON, determine which sensor is out of range by comparing SC Inlet Pressure and BARO Sensor kPa parameters with a scan tool.
3. Ignition OFF, disconnect the harness connector at the affected sensor.
4. Ignition OFF, allow sufficient time for the control module to power down. This can be verified by a no communication message on the scan tool. Test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.

• If greater than the specified range, test the low reference circuit terminal A or 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 C 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 0.2 volt.

• 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 terminal B and the 5-volt reference circuit terminal A. Verify the scan tool sensor parameter is greater than 95 kPa for the SCIAP sensor, or 199 kPa for the BARO sensor.

• 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 the affected sensor. Refer to Component Testing for instructions.

Component Test

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

1. Ignition OFF, remove the affected sensor.
2. Install a 3A fused jumper wire between the 5-volt reference terminal C of the sensor and 5-volt reference.
3. Install a jumper wire between the low reference terminal A of the sensor and ground.
4. Install a jumper wire at the signal terminal B sensor.
5. Connect a DMM between the jumper wire from terminal of the sensor and ground.
6. Ignition ON, 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.

Repair Instructions

* Supercharger Inlet Absolute Pressure Sensor Replacement
* Barometric Pressure Sensor Replacement
* Refer to Programming and Relearning for ECM setup and programming. Programming and Relearning

Repair Verification

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.
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