2010 Cadillac Truck SRX FWD V6-3.0L Page 1394

2010 Cadillac Truck SRX FWD V6-3.0L Page 1394

瀚慖f there is a condition with the spark plug, replace the spark plug.

7. Exchange the suspected spark plug with another cylinder that is operating correctly.

8. Engine idling, observe the scan tool Misfire Current Counter parameters. The misfire should not follow the spark plug exchange.

瀚慖f the misfire follows the spark plug, replace the spark plug.

9. If all conditions test normal, test or inspect for the following:

* A lean or rich Q17 fuel injector-Refer to Fuel Injector Solenoid Coil Test (LAU) (See: Powertrain Management/Fuel Delivery and Air

Induction/Fuel Injector/Testing and Inspection)Fuel Injector Solenoid Coil Test (LF1, LFW) (See: Powertrain Management/Fuel

Delivery and Air Induction/Fuel Injector/Testing and Inspection).

* An engine mechanical condition-Refer to Symptoms - Engine Mechanical (See: Engine, Cooling and Exhaust/Engine/Testing and

Inspection/Symptom Related Diagnostic Procedures/Symptoms - Engine Mechanical).

Repair Instructions

Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.

* Spark Plug Replacement (See: Engine, Cooling and Exhaust/Engine/Tune-up and Engine Performance Checks/Spark Plug/Service and

Repair)

* To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair

Verification for DTC P0420 or P0430. Refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code

Descriptions/Diagnostic Trouble Code (DTC) List - Vehicle) for DTC P0420 or P0430.

P0303

DTC P0300-P0306 (LF1, LFW)

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 P0300

- Engine Misfire Detected

DTC P0301

- Cylinder 1 Misfire Detected

DTC P0302

- Cylinder 2 Misfire Detected

DTC P0303

- Cylinder 3 Misfire Detected

DTC P0304

- Cylinder 4 Misfire Detected

DTC P0305

- Cylinder 5 Misfire Detected

DTC P0306

- Cylinder 6 Misfire Detected

Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position sensor and the camshaft position sensors in order to determine

when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect

individual misfire events. A misfire rate that is high enough can cause 3-way catalytic converter damage. The malfunction indicator lamp (MIL)

will flash ON and OFF when the conditions for catalytic converter damage are present. DTCs P0301 through P0306 correspond to cylinders 1

through 6. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder will set, and the corresponding fuel

injector is disabled. The ECM will re-enable the fuel injector after 4 crankshaft revolutions when the misfire is not current. The ECM will re-enable