2010 Cadillac Truck SRX FWD V6-3.0L Page 1121
Typical Scan Tool Data
Circuit Description
The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP),
and the throttle position sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.
* The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of
barometric pressure (BARO), throttle position, intake air temperature (IAT), and estimated MAP. The information from this model is
displayed on the scan tool as the MAF Performance Test parameter.
* The first intake manifold model describes the intake manifold and is used to estimate MAP as a function of the MAF into the manifold from
the throttle body and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF
estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance
Test 1 parameter.
* The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of
the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance
Test 2 parameter.
* The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model. The
information from this model is displayed on the scan tool as the Throttle Position Performance Test parameter.
The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the
MAF, MAP, and the throttle position sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible
failure combinations and the resulting DTC or DTCs.
Conditions for Running the DTC
* DTC P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335 or P0336 is not set.
* The engine speed is between 400-7,000 RPM.
* The IAT Sensor parameter is between -20掳 to +125掳C (-4掳 to +257掳F).
* The ECT Sensor parameter is between 69-127掳C (156-260掳F).
* This DTC runs continuously within the enabling conditions.
Conditions for Setting the DTCs
The engine control module (ECM) detects that the actual measured airflow from MAF, MAP, and throttle position is not within range of the
