Additional Wiring
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
Knock is the spontaneous auto-ignition of the remaining fuel/air mixture in the engine combustion chamber that occurs after normal combustion has started. It can occur under extreme vehicle operating conditions such as high engine temperature, high MAP, low humidity, and heavy loads to the engine. Knock is caused by excessive spark advance for the given engine operating conditions. Severe, continuous knock may be caused by carbon deposits, bad gasoline, and/or low octane fuel. Avoiding light audible knock is important for customer satisfaction while preventing excessive knock is important to protect engine components. The output voltage from the knock circuit represents the strength of the engine knock and is read by the engine controller. The knock system output voltage is not zero due to engine background noise, even when knock is not present. When the engine is operated under high load conditions where knock is possible, the knock voltage is tested to decide if it exceeds the knock voltage threshold. Knock has occurred when the knock voltage is at or above this knock threshold. When knock is detected a calibrated short term knock spark retard to be subtracted from the spark advance is calculated. The amount of retarded spark advance is based off a calibrated severity of the knock event. This retarded spark advance is used in the next ignition event to prevent further knock events. If knock continues, an additional amount of short term spark advance retard is added. When knock stops, short term knock spark retard is eliminated, the long term knock spark retard is reduced by a calibrated amount to recover some previously retarded spark advance. This decreases spark retard to improve engine performance.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
Knock is the spontaneous auto-ignition of the remaining fuel/air mixture in the engine combustion chamber that occurs after normal combustion has started. It can occur under extreme vehicle operating conditions such as high engine temperature, high MAP, low humidity, and heavy loads to the engine. Knock is caused by excessive spark advance for the given engine operating conditions. Severe, continuous knock may be caused by carbon deposits, bad gasoline, and/or low octane fuel. Avoiding light audible knock is important for customer satisfaction while preventing excessive knock is important to protect engine components. The output voltage from the knock circuit represents the strength of the engine knock and is read by the engine controller. The knock system output voltage is not zero due to engine background noise, even when knock is not present. When the engine is operated under high load conditions where knock is possible, the knock voltage is tested to decide if it exceeds the knock voltage threshold. Knock has occurred when the knock voltage is at or above this knock threshold. When knock is detected a calibrated short term knock spark retard to be subtracted from the spark advance is calculated. The amount of retarded spark advance is based off a calibrated severity of the knock event. This retarded spark advance is used in the next ignition event to prevent further knock events. If knock continues, an additional amount of short term spark advance retard is added. When knock stops, short term knock spark retard is eliminated, the long term knock spark retard is reduced by a calibrated amount to recover some previously retarded spark advance. This decreases spark retard to improve engine performance.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
Exhaust gas recirculation is a method of reducing emissions of oxides of nitrogen. As the inert exhaust gas is recirculated, the mixture absorbs heat in the combustion chamber without interacting with the fuel/air mixture and reduces the formation of NOx emissions. After the EGR monitor conditions are met, the EGR valve is turned on and off momentarily. The EGR monitor calculated the difference in engine roughness from the EGR off condition to the EGR condition. This engine combustion stability difference as measured by engine roughness is the measure of a functional EGR system.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The EGR valve has a position sensor and the EGR position rationality is designed to make sure that the valve moves freely within its operating range. Closed valve position reference check verifies that the valve is within its allowable upper and lower limits. The EGR position rationality test looks for a sustained error relative to commanded valve position.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The Evap Purge Monitor tests the integrity of the hoses/tube between the throttle body/intake and the fuel tank. The monitor is a two stage test and runs only after the Evap system passes the small leak test. Stage one is non-intrusive. The PCM monitors the purge vapor ratio and the ESM switch closed ratio. If the purge vapor ratio is above a calculated value, the monitor passes. If the ESM switch closed ratio is greater than calculated value when purge flow is greater than a minimum value, the monitor passes. Stage two is an intrusive test and runs only if stage one does not pass. The PCM commands the purge solenoid to flow at a specified rate to force the purge vapor ratio to update. The ratio is compared to a calibrated specification. If it is less than specified, a one trip failure is recorded. This test can detect if the purge hose is off, obstructed, or the purge valve is not operational.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The Evap Purge Monitor tests the integrity of the hoses/tube between the throttle body/intake and the fuel tank. The monitor is a two stage test and runs only after the Evap system passes the small leak test. Stage one is non-intrusive. The PCM monitors the purge vapor ratio and the ESM switch closed ratio. If the purge vapor ratio is above a calculated value, the monitor passes. If the ESM switch closed ratio is greater than calculated value when purge flow is greater than a minimum value, the monitor passes. Stage two is an intrusive test and runs only if stage one does not pass. The PCM commands the purge solenoid to flow at a specified rate to force the purge vapor ratio to update. The ratio is compared to a calibrated specification. If it is less than specified, a one trip failure is recorded. This test can detect if the purge hose is off, obstructed, or the purge valve is not operational.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
Fuel level is recorded when the ignition key is turned off and is compared to the fuel level when the ignition key is turned back on. The PCM recognizes an increase in fuel level and will fail the Medium leak test because the fuel cap is broken or not installed properly. GAS CAP will be displayed in odometer to inform the owner that the cap is off of loose.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The fuel level rationality will set a fault for a fuel level reading that does not change over an accumulated mileage threshold to keep stuck high or stuck low fuel levels from disabling OBD monitors. If the vehicle is fitted with a saddle tank fuel system this feature includes diagnostics for both of the sending units and diagnostics for a siphon tube that has become disconnected or plugged. The power up test looks to see a large enough fuel level voltage change from the last key-off to the following engine run. The engine run test looks to see a fuel level voltage change over an accumulated mileage.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
The vehicle speed sensor rationality is a continuous test that monitors the vehicle speed sensor for lack of activity. The rationality will not run if a limp-in exists for MAP, Throttle Position, and Engine Coolant Temperature. If vehicle speed sensor is below a minimum threshold for a period of time after the vehicle is operated at a sufficient load, a failure will be indicated.