Diesel Powertrain Control Software
DIESEL POWERTRAIN CONTROL SOFTWAREEngine RPM Limiter
The PCM limits the engine RPM by cutting off fuel whenever the engine RPM limit is detected The RPM limit for the F-Super Duty and E-Series is 4,000 RPM. The purpose of the engine RPM limiter is to prevent damage to the powertrain.
Flash Electrically Erasable Programmable Read Only Memory (EEPROM)
The flash EEPROM is an integrated circuit (IC) within the powertrain control module (PCM) and the fuel injection control module (FICM). This integrated circuit contains the software code required by the PCM to control the powertrain and by the FICM to control the fuel injectors. One feature of the flash EEPROM is that it can be electrically erased and then reprogrammed without removing the PCM or the FICM from the vehicle. If a software change is required to the PCM or the FICM, the modules no longer need to be replaced, but can be reprogrammed. The reprogramming is carried out through the data link connector (DLC).
Failure Mode Effects Management (FMEM)
The FMEM system is an alternate 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.
High Speed Controller Area Network (CAN)
The high speed CAN is based on SAE J2284, 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 500 k/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 high (+) and CAN low (-) lines to the DLC. The PCM connection to the DLC is typically done with a 2-wire, twisted pair cable used for network interconnection. The diagnostic data such as self-test or PIDs can be accessed with a diagnostic tool. Information on diagnostic tool equipment is described in Diagnostic Methods.
Keep Alive Memory (KAM)
The PCM stores information in KAM (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. KAM remains powered when the vehicle key is off so that this information is not lost.
Multiplexing
The increased number of modules on the vehicle dictate a more efficient method of communication. 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 (CAN2H/CAN2L). Modules communicate with the PCM using CAN communications, which determines the priority in which the signals are sent. Refer to the High Speed Controller Area Network (CAN) for additional information.
Oil Cooler Performance Monitor
The software in the powertrain control module (PCM) provides the strategy control for the oil cooler performance monitor. The oil cooler monitor compares the engine coolant temperature to the engine oil temperature during normal engine operation. The oil cooler system maintains an acceptable engine oil temperature by transferring the heat generated in the engine oil to the engine cooling system.
The oil cooler monitor is enabled after the thermostat opens, the engine oil temperature is greater than the engine coolant temperature, and the engine speed is greater than a calibrated threshold. Once the enabling conditions are met, the oil cooler monitor calculates the difference between the engine oil temperature and engine coolant temperature and compares the readings to an expected threshold. The expected threshold is dependent on the vehicle speed and engine load conditions. If the temperature difference exceeds the maximum limit for greater than a specific amount of time, DTC P012F sets and the powertrain malfunction indicator (wrench) on the instrument cluster illuminates. This monitor runs continuously once the enabling conditions are met.
Power and Ground Signals
Gold Plated Pins
NOTE: Gold plated terminals should only be replaced with new gold plated terminals.
Some engine control hardware has gold plated pins within the connectors and mating harness connectors to improve electrical stability for low current draw circuits and to enhance corrosion resistance. The electronic engine control (EEC) components equipped with gold terminals vary by vehicle application.
Keep Alive Power (KAPWR)
The KAPWR circuit provides a constant voltage input independent of ignition switch state to the PCM. This voltage is used by the PCM to maintain the keep alive memory (KAM).
Power Ground (PWR GND)
The PWR GND circuit(s) is directly connected to the battery negative terminal. PWR GND provides a return path for the PCM VPWR circuits.
Signal Return (SIG RTN)
The SIG RTN circuit(s) is a dedicated return path for VREF applied components.
Vehicle Buffered Power (VBPWR)
VBPWR is a regulated voltage supplied by the PCM to vehicle sensors. These sensors require a constant 12 volts for operation and cannot withstand VPWR voltage variations. VBPWR is regulated to VPWR minus 1.5 volts and is also current limited to protect the sensors.
Vehicle Power (VPWR)
VPWR is the primary source of PCM power. VPWR is switched through the EEC power relay and is controlled by the ignition switch.
Vehicle Reference Voltage (VREF)
VREF is a consistent positive voltage (5.0 volts ± 0.5) provided by the PCM. VREF is typically used by 3-wire sensors and some digital input signals.
Powertrain Control Module (PCM)
The center of the EEC system is the PCM. The PCM contains both engine and transmission microprocessors. Operating information, as well as fault information, is communicated between the 2 processors through controller area network (CAN) communications. Both can be programmed individually, however, the PCM is replaced as an assembly. The PCM has 3 electrical connectors (122 pins total). The PCM receives input from sensors and other electronic components (switches and relays) and places this information into random access memory (RAM) or keep alive memory (KAM). Based on information programmed into its read-only memory (ROM), the PCM generates output signals to control various relays, solenoids, and actuators. For vehicles equipped with manual transmissions, only 2 electrical connectors are used.
The transmission control module (TCM) controls the power monitor strategy. The power monitor monitors the engine speed at idle. If an abnormal engine speed increase is detected, the power monitor commands the fuel injection control module (FICM) off in an effort to maintain a normal idle speed. For manual transmission vehicles, the power monitor is the only active TCM function. DTCs are stored if the power monitor is active.
Powertrain Malfunction Indicator (Wrench)
The powertrain malfunction indicator (wrench) informs the driver that the PCM has detected a non OBD related component or system concern. When this occurs a DTC is set. The powertrain malfunction indicator (wrench) turns off through an ignition reset if the conditions are no longer met. The powertrain malfunction indicator (wrench) is located in the instrument cluster. The powertrain malfunction indicator (wrench) is illuminated by a PCM message sent through the controller area network (CAN) to the instrument cluster. To clear the DTCs, a command from the scan tool must be sent to the PCM.
For additional information, refer to Instrumentation, Message Center and Warning Systems, Instrument Panel Cluster (IPC).
Vane Sweep
The PCM commands the variable geometry turbo actuator duty cycle from 15% to 85% in a step pattern to help the turbo vanes achieve full movement. Vane sweep occurs when the following conditions are present:
- The vehicle is stopped.
- The EGR is commanded off.
- The engine speed is less than 1,160 RPM.
- The engine oil temperature is greater than a calibrated value.
Vane sweep repeats approximately every hour if the previous conditions still exist. Vane sweep may occur during scan tool commanded test functions.
Vehicle Speed Limiter
NOTE: Maximum speed may vary with load and axle ratio.
For F-250/350 and E-Series applications, a diesel engine equipped vehicle is limited to a maximum speed of approximately 153 km/h (95 mph). For F-450/550 applications, a diesel engine equipped vehicle is limited to a maximum speed of approximately 130 km/h (81 mph).