Circuit/System Verification
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that DTCs P0698 or P0699 are not set.
- If any of the DTCs are set, refer to DTC P0698 or P0699 .
- Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust .
- Verify that the engine is in good mechanical condition before continuing with this diagnostic. Refer to Symptoms - Engine Mechanical .
- Ignition OFF for 90 seconds, determine the current vehicle testing altitude.
- Ignition ON, observe the scan tool MAP Sensor parameters. Compare the parameter to the Altitude Versus Barometric Pressure . The BARO sensor pressure parameter should be within the specified range indicated in the table.
- Ignition ON, observe the scan tool MAP and BARO parameters. The MAP and BARO sensor parameters should be within 14 kPa of each other.
- Engine running, observe the scan tool MAP Sensor parameter. Slowly increase the engine speed to 2,000 RPM, then allow the engine speed to return to a stable idle. The MAP Sensor parameter should increment to a higher value at 2,000 RPM and then return to near BARO at idle speed.
- Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.