2010 Cadillac CTS Sedan AWD V6-3.6L Page 1299
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
the fuel injector after 8 crankshaft revolutions when the misfire is not current, if the vehicle is equipped with a manual transmission.
Conditions for Running the DTC
* DTC P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P0338, or P0461-P0463 is not set.
* The engine speed is between 400-7,000 RPM and steady.
* The evaporative emissions (EVAP) leak detection is not active.
* The delivered torque signal is greater than 5 % at idle.
* The delivered torque signal is between 6-29 % with the transmission in drive.
* The intake air temperature (IAT) is warmer than -30掳C (-22掳F).
* The fuel level is greater than 11 %.
* The ECM is not in fuel cut-off or decel fuel cut-off mode.
* The increase in engine speed is less than 2,500-4,600 RPM/second.
* DTCs P0300 through P0306 run continuously when the above conditions exist for greater than 1,000 engine revolutions. 200 revolutions
after the first failure.
Conditions for Setting the DTC
P0300
The ECM detects a crankshaft rotation speed variation indicating a misfire rate sufficient to cause emissions levels to exceed a predetermined value.
P0301, P0302, P0303, P0304, P0305, P0306
The ECM detects a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed
mandated standards.
Action Taken When the DTC Sets
* DTCs P0300-P0306 are Type B DTCs.
* When the MIL is flashing, the injector may be disabled for the misfiring cylinder to protect the catalytic converter.
* Depending on the conditions that set the code, the engine may go into Open Loop.
Conditions for Clearing the DTC
* DTCs P0300-P0306 are Type B DTCs.
* The DTC must pass under the same conditions that were present when the DTC failed.
Diagnostic Aids
* A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources:
- A tire or wheel that is out of round or out of balance
- Variable thickness brake rotors
- An unbalanced drive shaft
- Certain rough road conditions
- Transmission operation
- A damaged accessory drive component or belt
* High resistance in the circuits of the injectors may set a misfire DTC without setting an injector DTC. Test the injector circuits of the affected
cylinder(s) for a high resistance if you suspect a condition.
* If the condition is intermittent, observing the scan tool IC Circuit Test and Fuel Injector Circuit Test Status parameters may help isolate the
condition. The circuit test status parameters will change from OK or Not Run to Fault if a condition exists.
Reference Information
Schematic Reference
Engine Controls Schematics (LLT) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics
(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
