Powertrain Control Software
POWERTRAIN CONTROL SOFTWAREController Area Network (CAN)
The CAN is based on society of automotive engineers (SAE) J2284, international standard organization (ISO)-11898, and is a serial communication language protocol used to transfer messages (signals) between electronic control modules or nodes. Two or more signals can be sent over one CAN circuit allowing 2 or more electronic modules or nodes to communicate with each other. This communication, or multiplexing, network operates at 500k/sec (kilobytes per second) and allows the electronic modules to share their information messages.
Included in these messages is diagnostic data sent over the CAN+ and CAN- lines to the data link connector (DLC). The powertrain control module (PCM) connection to the DLC is done with a 2-wire, twisted pair cable used for network interconnection. The diagnostic data such as self-test or parameter identification (PIDs) can be accessed with a scan tool. Information on scan tool equipment is described in Diagnostic Methods, Scan Tool Setup and Functionality.
Cold Idle Kicker
The cold idle kicker strategy provides an increase in idle speed during cold engine warm up. During extended idle conditions, the PCM increases engine speed up to 1,100 RPM (normally 725 RPM for manual, 650 RPM for auto) to achieve a faster engine warm-up. The PCM uses the engine oil temperature (EOT) sensor input and adjusts the RPM accordingly, to a maximum of 1,100 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.
Diesel Particulate Filter Regeneration
NOTE: Regeneration may occur during normal operation. During regeneration, diagnostic procedures may display biased values. If a regeneration occurs during diagnostic procedures, allow the process to complete before continuing diagnostics.
During normal vehicle operation the PCM estimates the amount of particulates that accumulate in the diesel particulate filter. The estimated amount of particulates is based on the vehicle operating conditions such as speed and load. Additionally the PCM monitors the following:
- amount of time since the last diesel particulate filter regeneration
- battery voltage
- distance travelled since the last diesel particulate filter regeneration
- engine coolant temperature (ECT)
- engine speed
- exhaust gas temperature bank 1, sensor 1 (EGT11)
- exhaust gas temperature bank 1, sensor 2 (EGT12)
- exhaust gas temperature bank 1, sensor 3 (EGT13)
- fuel level
- fuel temperature
- intake air temperature (IAT)
- turbocharger condition
When the appropriate conditions are met, the PCM initiates a diesel particulate filter regeneration. The diesel particulate filter regeneration can occur at idle. The PCM may increase the engine speed at idle to maintain the correct temperature conditions for an optimum diesel particulate filter regeneration.
Engine RPM/Vehicle Speed Limiter
The PCM limits the engine RPM by cutting off fuel whenever the engine RPM limit is detected. The purpose of the engine RPM limiter is to prevent damage to the powertrain. The RPM limit for the F-Super Duty is 3,800 RPM. The vehicle speed is limited to 153 km/h (95 mph) for the F250/F350 and 130 km/h (81 mph) for the F450/F550.
Fail-Safe Cooling Strategy
The fail-safe cooling strategy is activated by the PCM only in the event that an overheating condition has been identified. This strategy provides engine temperature control when the engine coolant temperature exceeds certain limits. A cooling system failure such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components could occur. When the fuel injectors are disabled, the respective cylinders work as air pumps, and this air is used to cool the cylinders. A wide open throttle (WOT) delay is incorporated if the engine coolant temperature is exceeded during WOT operation. At WOT, the injectors function for a limited amount of time allowing the customer to complete a passing maneuver. If overheating continues, the strategy begins to disable the fuel injectors. If the overheating condition continues and a critical temperature is reached, all fuel injectors are turned off and the engine is disabled.
Failure Mode Effects Management (FMEM)
The FMEM system is an alternative strategy in the PCM designed to maintain vehicle operation if one or more critical sensor inputs fail. 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 diagnostic trouble codes (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 (EEPROM)
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 Trim
The fuel control system uses fuel trim tables stored in the PCM keep alive memory (KAM) to compensate for the variability that occurs in fuel system components due to normal wear and aging. Fuel trim tables are based on fuel mass.
Multiplexing
Multiplexing is the process of communicating several messages over the same signal path. This process allows multiple modules to communicate with each other through the signal path (CAN+ and CAN-). Modules communicate with the PCM using CAN communications, to determine the priority in which the signals are sent.
Multiplexing Implementation
For additional information, refer to Information Bus (Module Communications Network), Module Communications Network.