2010 Cadillac Truck SRX FWD V6-3.0L Page 2008
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
P2188
DTC P2178 or P2188
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 P2178
- Fuel Trim System Rich at Cruise or Acceleration
DTC P2188
- Fuel Trim System Rich 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 trim fuel delivery adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0
percent. If the O2S indicate a rich condition, fuel trim values will be below 0 percent. 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
P2178
* Before the ECM can report DTC P2178 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 grams/second.
* The throttle angle is less than 100 percent.
* The engine load is between 17-55 percent.
* The fuel system is in closed loop.
* The engine is not in decel fuel cut-off (DEFCO).
* 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 percent.
* The amount of air flow into the engine is greater than 7,000 grams.
* DTC P2178 run continuously once the above conditions are met for at least 300 seconds.
P2188
* Before the ECM can report DTC P2188 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 480-1,001 RPM.
* The engine load is between 7-32 percent.
* The MAF is between 1-8 grams per second.
* The fuel system is in closed loop.
* The engine is not in decel fuel cut-off (DEFCO).
* 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).
