Dodge
Challenger 2009-2010
-
PCM -
MAIN OPERATIONS
Many of these operations are identical on both the 5.7L and the 6.1L HEMI
engines. (2008-10)
The PCM operates the fuel system. The PCM is a pre-programmed,
dual microprocessor digital computer. It regulates ignition timing, air-fuel
ratio, emission control devices, charging system, certain transmission
features, speed control, air conditioning compressor clutch engagement and idle
speed.
The PCM can "adapt" its programming to meet changing operating
conditions. These conditions are stored over a short (quick learn) or longer
(standard learn) "start cycle" engine periods.
The PCM has two main "modes of operation" and that will be discussed
further down.
The PCM receives input signals from various switches and sensors. Based on
these inputs, the PCM regulates various engine and vehicle operations through
different system components.
These components are referred to as Powertrain
Control Module (PCM) Outputs.
The sensors and switches that provide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon inputs it receives from sensors that
react to:
Engine rpm, manifold absolute pressure, engine coolant temperature, throttle
position, pedal value, transmission gear selection (automatic transmission),
vehicle speed and the brake switch.
The PCM adjusts idle speed based on inputs it receives from sensors that react
to: throttle position, vehicle speed, transmission gear selection, engine
coolant temperature and from inputs it receives from the air conditioning
clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM
also adjusts the generator charge rate through control of the generator field
and provides speed control operation.
PCM Inputs:
1. A/C select AND request via CAN
communication bus
2. Auto shutdown (ASD) sense
3. Brake switches 1 AND 2
4. Direct Battery voltage
5. EGR Position sensor (Not used on current
GEN.III Hemi with VVT)
6. EVAP purge solenoid current sense
7. Camshaft position sensor signal
8. Crankshaft position sensor
9. CAN C bus communication for internal
module communication and ATA link connection for scan tools
10. Engine coolant temperature sensor
11. 5 volts (primary)
12. 5 volts (secondary)
13. Fuel level via CAN communication bus from IPM
14. Generator (battery voltage sense) output
15. Ignition circuit sense (ACC AND Run/Start via hardwire from the Total
Integrated Power Module (TIPM)
while the Crank indication is via
CAN communication bus)
16. Intake manifold air temperature sensor
17. Evaporative system ESIM vacuum switch (if equipped)
18. Manifold absolute pressure (MAP) sensor
19. Oil pressure
20. Oil Temp
21. Oxygen sensors signals
22. Park/neutral switch
23. Power ground
24. Sensor return
25. Signal ground
26. Speed control switch states are determined by SCM and transmitted over the
bus via CAN bus
27. SRV position sensor signal
28. Throttle position sensors and Pedal value sensors
29. Transmission pressure switch inputs (42RLE)
30. Transmission variable line pressure sensor (42RLE)
31. Transmission temperature sensor (42RLE)
32. Vehicle speed (ABS equipped) via CAN C bus from ABS module
PCM Outputs
1. Vehicle Speed (Non-ABS) from IPM via
CAN C and Trans Turbine sensors (with pinion factor)
2. A/C clutch relay
3. Auto shutdown (ASD) relay coil
4. CAN C bus messages for speedometer
(non-ABS packages), voltmeter or generator lamp (if equipped), fuel gauge,
5
Oil pressure gauge/lamp, engine coolant temperature gauge and speed
control indication warning lamp
6. CAN bus communication for inter
module communication and data link connection for scan tools
7. EGR valve control solenoid (if
equipped)
8. Electronic Throttle Control (ETC)
motor
9. EVAP Purge solenoid
10. Fuel injectors
11. Fuel pump relay
12. Generator field driver
13. Ignition coils
14. Malfunction indicator lamp (also known as MIL). Driven through CAN-Bus
Messages.
15. Oxygen sensor heater elements
16. Radiator cooling fan relay via CAN-Bus message to TIPM
17. Short Runner Valve (SRV) actuator (if equipped)
18. Tachometer (if equipped). Driven through Bus Messages.
19. Transmission solenoids (42RLE only)
20. Transmission power relay
PCM (Powertrain Control Module)
also called
NGC (Next Generation Controller)
MODES OF OPERATION
As input signals to the Powertrain Control Module
(PCM) change, the PCM adjusts its response to the output devices. For example,
the PCM must calculate different injector pulse width and ignition timing for
idle than it does for wide open throttle (WOT).
The
PCM will operate in two different modes:
1. Open Loop
2. Closed Loop.
During Open Loop modes, the PCM receives input signals and responds only
according to preset PCM programming. Input from the oxygen (O2S) sensors is not
monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input.
This input indicates to the PCM whether or not the calculated injector pulse
width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1
part fuel.
By monitoring exhaust oxygen content through the O2S sensor, the PCM can fine
tune the injector pulse width. This is done to achieve optimum fuel economy
combined with low emission engine performance.
The fuel injection system has the following modes of operation:
1. Ignition switch ON
2. Engine start-up (crank)
3. Engine warm-up
4. Idle
5. Cruise
6. Acceleration
7. Deceleration
8. Wide open throttle (WOT)
9. Ignition switch OFF
The ignition switch On, engine start-up (crank), engine warm-up, acceleration,
deceleration and wide open throttle (WOT) modes are Open Loop modes. The idle
and cruise modes, (with the engine at operating temperature) are Closed Loop
modes.
IGNITION SWITCH (KEY-ON) MODE:
This is an Open Loop mode.
When the fuel system is activated by the ignition switch, the following actions
occur:
1. The PCM determines atmospheric air pressure from the MAP sensor input to
determine basic fuel strategy.
2. The PCM monitors the engine coolant temperature sensor input. The PCM
modifies fuel strategy based on this input.
3. Intake manifold air temperature sensor input is monitored.
4. Throttle position sensors (TPS) and pedal value sensors are monitored.
5. The auto shutdown (ASD) relay is energized by the PCM for approximately
three seconds.
6. The fuel pump is energized through the fuel pump relay by the PCM. The fuel
pump will operate for approximately three seconds unless the engine is
operating or the starter motor is engaged.
7. The O2S sensor heater element is energized via the O2S heater drivers (solid
state devices) internal to the PCM. These drivers provide a PWM 0-12V signal to
heat the O2S heater elements to optimize the O2S sensor signal output. The O2S
sensor input is not used by the PCM to calibrate air-fuel ratio during this
mode of operation.
ENGINE START-UP MODE:
This is an Open Loop mode. The following actions occur when the starter motor
is engaged.
The PCM receives inputs from:
1. Direct Battery voltage
2. Pedal Value Sensors (PVS)
3. Engine coolant temperature sensor
4. Crankshaft position sensor
5. Intake manifold air temperature sensor
6. Manifold absolute pressure (MAP) sensor
7. Throttle position sensors (TPS)
8. Camshaft position sensor signal
The PCM monitors the crankshaft position sensor. If the PCM does not receive a
crankshaft position sensor signal within approximately 3 seconds of cranking
the engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through the fuel pump relay located in
the TIPM. Voltage is applied to the fuel
injectors with the ASD relay via the PCM. The PCM will then control the
injection sequence and injector pulse width by actuating ground circuit to each
individual injector on and off.
The PCM determines the proper ignition timing according to input received from
the crankshaft position sensor.
ENGINE WARM-UP MODE:
This is an Open Loop mode. During engine warm-up, the PCM receives inputs from:
1. Direct Battery voltage
2. Crankshaft position sensor
3. Engine coolant temperature sensor
4. Intake manifold air temperature sensor
5. Manifold absolute pressure (MAP) sensor
6. Throttle position sensors (TPS)
7. Camshaft position sensor signal
8. Park/neutral switch (gear indicator signal)
9. Pedal Value Sensors (PVS)
10. Air conditioning select signal (if equipped)
11. Air conditioning request signal (if equipped)
Based on these inputs the following occurs:
1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The
PCM will then control the injection sequence and injector pulse width by
turning the ground circuit to each individual injector on and off.
2. The PCM adjusts engine idle speed through the electronic throttle control
(ETC) motor and adjusts ignition timing accordingly.
3. The PCM operates the A/C compressor clutch through the clutch relay. This is
done if A/C has been selected by the vehicle operator and requested by the A/C
thermostat.
4. When engine has reached operating temperature, the PCM will begin monitoring
O2S sensor to control the air/fuel ratio. The system will then leave the
warm-up mode and go into closed loop operation.
IDLE MODE:
When the engine is at operating temperature, this is a Closed Loop mode.
At idle speed, the PCM receives inputs from:
1. Air conditioning select signal (if
equipped)
2. Air conditioning request signal (if
equipped)
3. Battery voltage
4. Crankshaft position sensor
5. Engine coolant temperature sensor
6. Intake manifold air temperature
sensor
7. Manifold absolute pressure (MAP)
sensor
8. Pedal Value Sensors (PVS)
9. Throttle position sensors (TPS)
10. Camshaft position sensor signal
11. Battery voltage
12. Park/neutral switch (gear indicator signal)
13. Oxygen sensors
Based on these inputs, the following occurs:
1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The
PCM will then control injection sequence and injector pulse width by turning
the ground circuit to each individual injector on and off.
2. The PCM monitors the O2S sensor input and adjusts air-fuel ratio by varying
injector pulse width. It also adjusts engine idle speed through the electronic
throttle control (ETC) motor.
3. The PCM adjusts ignition timing by increasing and decreasing spark advance.
4. The PCM operates the A/C compressor clutch through the A/C clutch relay.
This happens if A/C has been selected by the vehicle operator and requested by
the A/C thermostat.
CRUISE MODE:
When the engine is at operating temperature, this is a Closed Loop mode.
At cruising speed, the PCM receives inputs from:
1. Air conditioning select signal (if
equipped)
2. Air conditioning request signal (if
equipped)
3. Battery voltage
4. Engine coolant temperature sensor
5. Crankshaft position sensor
6. Intake manifold air temperature
sensor
7. Manifold absolute pressure (MAP)
sensor
8. Pedal Value Sensors (PVS)
9. Throttle position sensors (TPS)
10. Camshaft position sensor signal
11. Park/neutral switch (gear indicator signal)
12. Oxygen (O2S) sensors
Based on these inputs, the following occurs:
1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The
PCM will then adjust the injector pulse width by turning the ground circuit to
each individual injector on and off.
2. The PCM monitors the O2S sensor input and adjusts air-fuel ratio.
3. The PCM adjusts ignition timing by turning the ground path to the coils on
and off.
4. The PCM operates the A/C compressor clutch through the clutch relay. This
happens if A/C has been selected by the vehicle operator and requested by the
A/C thermostat.
ACCELERATION MODE:
This is an Open Loop mode. The PCM recognizes an abrupt increase in throttle
position or MAP pressure as a demand for increased engine output and vehicle
acceleration. The PCM increases injector pulse width in response to increased
throttle opening.
DECELERATION MODE:
When the engine is at operating temperature, this is an Open Loop mode.
During hard deceleration, the PCM receives the following inputs.
1. Air conditioning select signal (if
equipped)
2. Air conditioning request signal (if
equipped)
3. Battery voltage
4. Engine coolant temperature sensor
5. Crankshaft position sensor
6. Intake manifold air temperature
sensor
7. Manifold absolute pressure (MAP)
sensor
8. Pedal Value Sensors (PVS)
9. Throttle position sensors (TPS)
10. Camshaft position sensor signal
11. Park/neutral switch (gear indicator signal)
12. Vehicle speed
If the vehicle is under hard deceleration with the proper rpm and closed
throttle conditions, the PCM will ignore the oxygen sensor input signal. The
PCM will enter a fuel cut-off strategy in which it will not supply a ground to
the injectors. If a hard deceleration does not exist, the PCM will determine
the proper injector pulse width and continue injection.
The PCM adjusts ignition timing by turning the ground path to the coils on and
off.
WIDE OPEN THROTTLE MODE (WOT)
This is an Open Loop mode. During wide open throttle operation, the PCM
receives the following inputs.
1. Battery voltage
2. Crankshaft position sensor
3. Engine coolant temperature sensor
4. Intake manifold air temperature sensor
5. Manifold absolute pressure (MAP) sensor
6. Pedal Value Sensors (PVS)
7. Throttle position sensors (TPS)
8. Camshaft position sensor signal
During wide open throttle conditions, the following occurs:
1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The
PCM will then control the injection sequence and injector pulse width by turning
the ground circuit to each individual injector on and off. The PCM ignores the
oxygen sensor input signal and provides a predetermined amount of additional
fuel. This is done by adjusting injector pulse width.
2. The PCM adjusts ignition timing by turning the ground path to the coil on
and off.
OPERATION - IGNITION CIRCUIT SENSE
When the ignition key is inserted, the position of the key is transmitted via
the CAN bus to Integrated Power Module (IPM). When the key position is rotated
to the ACC position or Run/Start position, the IPM energizes the Ignition ACC
and/or Run/Start feed which will wake up the Powertrain
Control Module (PCM) accordingly.
These feeds are essentially fused switched battery voltage feeds fabricated by
the IPM with relays or solid state devices. There is not Ignition Start feed to
the PCM - this is handled by a CAN bus message from IPM to PCM. NOTE: Only on
those applications with the 42RLE does the PCM receive an Ignition ACC feed.
IGNITION
SWITCH OFF MODE
When ignition switch is turned to OFF position, the PCM stops operating the
injectors, ignition coil, ASD relay and fuel pump relay.
This touches on just some of the basic functions of our PCM.
IF there is interest, I will continue with another added post on the very extensive
emissions criteria that the PCM meets.
It is just as elaborate if not more sophisticated on active and passive
monitoring of engine components to meet all Federal emissions standards.