Saturday, November 2, 2019

2010 Cadillac Truck Escalade ESV AWD V8-6.2L Page 1946

2010 Cadillac Truck Escalade ESV AWD V8-6.2L Page 1946

P0172

DTC P0171, P0172, P0174, or P0175

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC P0171

- Fuel Trim System Lean Bank 1

DTC P0172

- Fuel Trim System Rich Bank 1

DTC P0174

- Fuel Trim System Lean Bank 2

DTC P0175

- Fuel Trim System Rich Bank 2

Circuit/System Description

The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel

economy, and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop (CL). During Open Loop, the ECM

determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During CL, the ECM adds HO2S inputs and level of

purge to calculate the short and long term fuel trim (FT) adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 %.

If the HO2S indicates a rich condition, the FT values will be below 0 %. The short term FT values change rapidly in response to the HO2S voltage

signals. The long term FT makes coarse adjustments in order to maintain an optimum air/fuel ratio. A block of cells contain information arranged in

combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term FT diagnostic is based on an average

of cells currently being used. The ECM selects the cells based on the engine speed and load. The FT diagnostic will conduct a test to determine if a

rich failure actually exists or if excessive vapor from the evaporative emission (EVAP) canister is causing a rich condition.

If the ECM detects an excessively lean condition, DTC P0171 or P0174 sets. If the ECM detects an excessively rich condition, DTC P0172 or

P0175 sets.

Conditions for Running the DTC

* DTCs P0030, P0036, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0128, P0130, P0131, P0132,

P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0208, P0220, P0300, P0301-P0304, P0442, P0443, P0446, P0449,

P0452, P0453, P0455, P0496, P1106, P1107, P1114, P1115, P1133, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176 are not set.

* The engine is in Closed Loop status.

* The engine coolant temperature (ECT) is between -40 and +150锟斤拷C (-40 and +302锟斤拷F).

* The intake air temperature (IAT) is between -20 and +150锟斤拷C (-4 and +302锟斤拷F).

* The manifold absolute pressure (MAP) is between 10-255 kPa (1.45-37 psi).

* The vehicle speed is less than 134 km/h (83 mph).

* The engine speed is between 375-7,000 RPM.

* The mass air flow (MAF) is between 1-510 g/s.

* The barometric pressure (BARO) is more than 70 kPa (10.2 psi).

* The fuel level is more than 10 %.

* This diagnostic runs continuously when the above conditions have been met.

Conditions for Setting the DTC

* The average long term FT weighted average value is more or less than a calibrated value.

* The above condition is present for approximately 3 min after the Conditions for Running the DTC have been met.

Action Taken When the DTC Sets

The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the ECM stores this information in the

Failure Records. If the diagnostic reports a failure on the second ignition cycle the ECM records the operating conditions at the time of the failure.

The ECM writes the operating conditions to the Freeze Frame and updates the Failure Records. The ECM illuminates the malfunction indicator

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