Powertrain Control Software

Auto Start Stop 

The auto start stop system helps reduce fuel consumption and decrease emissions by automatically shutting down the engine when the vehicle stops and the engine is idling, usually within 1500 ms (1.5 seconds). To initiate the auto start stop operation, the vehicle gear selector must be in DRIVE when the vehicle comes to a stop and the brake pedal must be fully applied. The engine automatically restarts when the brake pedal is released, usually within 200 ms (0.5 seconds), or when a vehicle system requires a restart, for example to recharge the battery or to maintain interior comfort settings.

The auto start stop system is defaulted to an ON state when the engine is started. To switch the auto start stop system OFF, press the auto start stop switch located on the center console. To turn the auto start stop system ON, press the auto start stop switch again. The auto start stop system can only be deactivated during the current ignition cycle.

The IPC auto start stop indicator illuminates when an auto start stop system inhibit or disable condition is present. During normal operation the auto start stop system may not stop the engine under the following conditions:

• The A/C, heat or defrost settings are ON
• The rear defroster is ON
• The battery has a low state of charge or is below 5°C (41°F) or above 60°C (140°F)
• The maximum engine off time is exceeded
• The engine operating temperature is less than 60°C (140°F)
• The gear selector is in the PARK, REVERSE, NEUTRAL or SECOND GEAR position
• The steering wheel is turned rapidly or is at a sharp angle
• Initial vehicle speed of greater than 4 km/h (2.5 MPH) and less than 2 seconds has elapsed
• The vehicle is on a steep road grade
• Elevation is above 10, 000 feet (3, 048 meters) approximately
• The CPP sensor indicates the clutch pedal is fully released

Any of the following conditions may result in an automatic restart of the engine:

• The blower fan speed is increased or the climate control temperature is changed
• An electrical accessory is turned ON or plugged in
• Incorrect brake vacuum
• The auto start stop switch is pressed to disable the system while the engine is stopped

Comprehensive Component Monitor 

The CCM is an on board strategy designed to monitor a concern in any electronic component or circuit that provides an input or output signal to the PCM and is not exclusively monitored by another monitor system. Inputs and outputs are considered inoperative when a concern exists due to a lack of circuit continuity, out of range value or rationality checks.

The CCM covers many components and the related circuits. The tests vary depending on the hardware, function, and type of signal. For example, analog inputs are typically checked for opens, shorts, and out of range values or rationality. This type of monitoring is carried out continuously. These tests may require the monitoring of several components and may only be carried out under the appropriate test conditions. Some outputs are also monitored for the correct function by observing the reaction of the control system to a given change in the output command. An example of this is the turbocharger control system.

In general, the CCM covers a broad range of individual component and circuit checks, and testing is carried out under various conditions. The CCM is enabled after the ignition switch is turned on. If a concern is detected that impacts emissions, the malfunction indicator lamp (MIL) is illuminated after 2 drive cycles.

The following are examples of some of the input and output components monitored by the CCM. The components monitored may belong to the engine, transmission, or any other PCM supported subsystem.

• The input components monitored include the engine oil temperature (EOT), accelerator pedal position (APP), and camshaft position (CMP) sensors.
• The output components monitored include the fuel pump.
• The MIL is activated after a concern is detected if the concern impacts emissions.

Cold Idle Kicker 

The cold idle kicker strategy provides an increase in idle speed during cold engine warm up. The PCM uses the ECT sensor and transmission position as primary inputs, and in certain conditions the PCM uses the ambient air temperature input to adjust the cold idle RPM up to a maximum of 1, 175 RPM.

Diesel Engine Power Monitor 

The diesel engine power monitor strategy resides in the PCM. The function of the diesel engine power monitor is to check the engine operation for unwanted fuel injections without a driver demand. During the diesel engine power monitor the PCM checks the commanded fuel injections and engine speed.

Engine Shutdown Timer 

Vehicles equipped with the engine shutdown timer have an instrument panel cluster message and an audible alert that notifies the driver 30 seconds prior to engine shutdown. When the engine shutdown occurs, the PCM broadcasts a shutdown message to all the vehicle modules. One minute after the engine shutdown occurs, the circuit deactivation ignition module (CDIM) electrically changes the ignition state to OFF and the vehicle goes into the normal delay accessory mode.

Engine shutdown occurs under the following conditions: Engine shutdown occurs under the following conditions:

• Vehicle speed below 1.6 km/h (1 mph) Vehicle speed below 1.6 km/h (1 mph)
• Engine coolant temperature is greater than 15°C (60°F) Engine coolant temperature is greater than 15°C (60°F)
• Transmission in the PARK or NEUTRAL position Transmission in the PARK or NEUTRAL position
• Engine shutdown occurs in 5 minutes with the parking brake applied.
• Engine shutdown occurs in 15 minutes without the parking brake applied
• The engine shutdown time may be increased in regeneration mode or scan tool mode (60 minutes maximum)
• Brake or accelerator pedal application in the 30 second window resets the engine shutdown timer
• Power take off (PTO) or auxiliary idle control system not active

Fuel Balancing And Control 

Fuel balancing and control is an algorithm designed to reduce differences in injected fuel quantity from cylinder to cylinder. The increase in crankshaft speed due to individual cylinder combustion events is measured. The amount of fuel injected to each cylinder is then adjusted up or down to minimize the difference in increase in crankshaft speed from cylinder to cylinder. Fuel balancing and control operates in closed loop control in an engine speed range of 500 to 2800 RPM and a commanded injection quantity of 3.5 to 75 mg per stroke.

Failure Mode Effects Management 

The FMEM system is an alternative strategy in the PCM designed to maintain vehicle operation if there is a concern with one or more critical sensor inputs. When a sensor input is perceived to be out of limits by the PCM, an alternative strategy is initiated. The PCM substitutes a fixed value and continues to monitor the incorrect sensor input. If the suspect sensor operates within limits, the PCM returns to the normal engine running strategy. FMEM operation results in continuous memory DTCs during normal engine operation and when carrying out the key on engine running (KOER) self-test mode.

Flash Electronically Erasable Programmable Read Only Memory 

The flash EEPROM is an integrated circuit within the PCM. This integrated circuit contains the software code required by the PCM to control the powertrain. One feature of the flash EEPROM is that it can be electronically erased and then reprogrammed without removing the PCM from the vehicle. The reprogramming is carried out through the DLC.

Fuel Mass Observer 

The fuel mass observer is an algorithm used to detect deviations in performance of all fuel injectors from nominal. The oxygen percentage as measured by the nitrogen oxides bank 1, sensor 2 (NOx12) is compared to a modeled oxygen percentage based upon the current fuel, boost, and EGR settings. The deviation between the measured and modeled oxygen percentage is expressed in terms of the error in fueling required to explain the deviation. This calculated error in fueling is then divided by the current requested fueling level to generate a ratio of percentage error in fueling. This fueling ratio is then filtered over time. If the filtered error in fueling ratio exceeds minimum or maximum limits, then a DTC is set.