Powertrain Control Outputs

Injector Driver Module
The Injector Driver Module controls power to the fuel injectors based on information received from the PCM. The Injector Driver Module receives two digital control signals from the PCM: The Fuel Delivery Control Signal and the Camshaft Position (CMP) signal. The Fuel Delivery Control Signal is used by the Injector Driver Module to control injection timing and injection duration. The CMP signal provides synchronization to the engine's first and the fifth injector (firing order, cylinders number one and four). The Injector Driver Module verifies that Fuel Delivery Control Signal and CMP occur at valid timing intervals for synchronization.





Exhaust Back Pressure Regulator
The exhaust back pressure is controlled to provide more heat to the coolant for cab heating when ambient air temperature is below 5°C (400 F) and engine oil temperature is between -10°C (15°F) and 83°C (182°F) during low load, low speed operating conditions. At high load, high speed conditions, the back pressure system is disabled.

The exhaust back pressure regulator solenoid and exhaust back pressure piston are contained in the turbocharger mounting pedestal. Turbocharger pressurized lube oil is routed to the exhaust back pressure solenoid. Oil regulated by the exhaust back pressure solenoid actuates the piston which operates the back pressure valve in the exhaust housing.





Injection Pressure Regulator
The Injection Pressure Regulator controls injection oil pressure. An electrical signal to a solenoid creates a magnetic field which applies a variable force on a valve servo to control pressure. The quantity of fuel delivered to the combustion chamber is proportional to injection control pressure.

An open circuit will result in minimum oil pressure and a no-start situation. A short circuit results in maximum oil pressure, and is limited by a mechanical pop-off valve to 27,580 kPa (4000 psi).





Tachometer Output
The Tachometer Output provides a signal from the PCM to the instrumentation system. The signal is a buffered representation of the Camshaft Position Sensor (CMP). An open or short circuit of the tachometer output wiring will result in an inoperative tachometer.





Glow Plug Relay Control
The Glow Plug (GP) Relay Control is used to energize the glow plugs for assisting cold engine start-up. Engine Oil Temperature, battery positive voltage (B+), and Barometric Pressure (BARO) are used by the PCM to calculate glow plug on-time and the length of the duty cycle. On-time normally varies between 10 and 120 seconds. With colder oil temperatures and lower barometric pressures, the plugs are on longer. If battery voltage is abnormally high, the duty cycle is shortened to extend plug life. (The glow plug relay will only cycle ON and OFF repeatedly when there is a system high voltage condition greater than 16 volts.) An open in the glow plug relay circuit will render the glow plugs inoperative. A short circuit will result in a glow plug's always ON condition.





Glow Plug Light Signal
The Glow Plug (GP) light signal controls the WAIT TO START indicator light located on the instrument panel. When the light goes OFF, the engine is ready to be started. The light comes ON every time a key ON reset occurs. On-time normally varies between 1 and 10 seconds. WAIT TO START light on-time is independent of glow plug relay on-time because the glow plugs may stay ON to improve performance until engine reaches operating temperature.

An open circuit in the glow plug light wiring will result in an inoperative glow plug light. A short circuit will result in a glow plug light always ON condition.