2010 Cadillac Truck SRX AWD V6-3.0L Page 2000
瀚慖f not within the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
7. If all circuits and connections test normal, replace the Q38 throttle body assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the repair.
* Throttle Body Assembly Replacement (LF1) (See: Powertrain Management/Fuel Delivery and Air Induction/Throttle Body/Service and
Repair/Removal and Replacement)Throttle Body Assembly Replacement (LAU) (See: Powertrain Management/Fuel Delivery and Air
Induction/Throttle Body/Service and Repair/Removal and Replacement)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, programming, and setup
P2177
DTC P2177 or P2187
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 P2177
- Fuel Trim System Lean at Cruise or Acceleration
DTC P2187
- Fuel Trim System Lean at Idle
Circuit 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 and Closed Loop. During Open Loop, the ECM determines fuel
delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop, the HO2S inputs are added and used by the
ECM to calculate short and long term fuel delivery adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0 %. If the
HO2S indicate a rich condition, fuel trim values will be below 0 %. Short term fuel trim values change rapidly in response to the HO2S signals.
Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.
Conditions for Running the DTC
P2177
* Before the ECM can report DTC P2177 failed, DTCs P0008, P0009, P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0019, P0020,
P0021, P0023, P0024, P0101, P0121, P0122, P0123, P0133, P0201, P0202, P0203, P0204, P0205, P0206, P0221, P0222, P0223, P0261,
P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0335, P0336, P0338,
P0443, P0458, P0459, P0461, P0462, P0463, P2068 P2088, P2089, P2090, P2091, P2092, P2093, P2094, and P2095 must run and pass.
* The engine speed is between 1,200-3,400 RPM.
* The mass air flow is between 7-83 g/s.
* The throttle angle is less than 100 %.
* The engine load is between 17-55 %.
* The fuel system is in Closed Loop.
* The engine is not in decel fuel cut-off.
* The long term fuel trim is active.
* The engine coolant temperature (ECT) is greater than 60掳C (140掳F).
* The intake air temperature (IAT) is less than 61掳C (142掳F).
* The evaporative emission (EVAP) canister purge solenoid valve is not enabled.
* The fuel level is greater than 12 %.
* The amount of air flow into the engine is greater than 7,000 g.
* DTC P2177 runs continuously when the above conditions are met for at least 300 s.
P2187
* Before the ECM can report DTC P2187 failed, DTCs P0008, P0009, P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0019, P0020,
P0021, P0023, P0024, P0101, P0121, P0122, P0123, P0133, P0201, P0202, P0203, P0204, P0205, P0206, P0221, P0222, P0223, P0261,
P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0335, P0336, P0338,
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