DaimlerChrysler LH New Yorker 1994, Электронное руководство по обслуживанию

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The PCM contains a voltage converter that changes
battery voltage to a regulated 8.0 volts. The 8.0 volts
power the camshaft position sensor, crankshaft posi-
tion sensor and vehicle speed sensor. The PCM also
provides a 5.0 volts supply for the engine coolant
temperature sensor, intake air temperature sensor,
manifold absolute pressure sensor and throttle posi-
tion sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the milage in new PCM. Use
the DRB scan tool to change the milage in the PCM.
Refer
to the appropriate Powertrain Diagnostic
Manual and the DRB scan tool.
TRANSMISSION CONTROL MODULE
The transmission control module (TCM) supplies
three inputs to the PCM:
•
Transaxle Gear Engagement (3.3L engines only)
•
Road Speed
•
Torque Management (3.5L engine only)
TRANSAXLE GEAR ENGAGEMENT (3.3L
ENGINES)
On 3.3L engines only, the TCM supplies an input
indicating transaxle gear engagement to the PCM
over the CCD Bus. The input allows the PCM to
adjust idle speed for smooth gear engagement.
ROAD SPEED
The transmission control module supplies the road
speed and distance traveled inputs to the PCM. From
these inputs and the throttle position sensor input,
the PCM determines when a deceleration condition
occurs.
TORQUE MANAGEMENT (3.5L ENGINE)
On 3.5L engines the PCM receives the torque man-
agement input from the transmission control module.
The PCM receives the input when the transmission
shifts gears. In response, the PCM shuts off a number
of fuel injectors when the transmission shifts gears.
PARK/NEUTRAL SWITCH
The automatic transaxle manual valve lever posi-
tion sensor supplies the park/neutral input to the
powertrain control module. The park/neutral switch
input tells the PCM whether the transmission is in
Park, Neutral, or a drive gear selection. This input
effects idle speed, fuel injector pulse width and igni-
tion timing.
SCI CIRCUITS
The powertrain control module (PCM) communi-
cates with the DRB scan tool through the serial com-
munication interface (SCI) receive and transmit cir-
cuits. Technicians can connect the DRB scan tool to
the data link connector. The data link connector con-
tains 6 terminals. Terminal 3 is the SCI Receive
circuit. Terminal 4 is the SCI Transmit circuit.
AIR CONDITIONING PRESSURE TRANSDUCER—
PCM INPUT
The powertrain control module (PCM) monitors the
A/C compressor discharge (high side) pressure
through the air conditioning pressure transducer. The
transducer supplies an input to the PCM. The PCM
engages the A/C compressor clutch if pressure is suffi-
cient for A/C system operation.
ASD SENSE—PCM INPUT
The automatic shut down (ASD) sense circuit in-
forms the powertrain control module when the ASD
relay contacts close. When energized, the ASD relay
supplies battery voltage to the fuel injectors and igni-
tion coils.
BATTERY VOLTAGE—PCM INPUT
The PCM monitors the battery voltage input to
determine fuel injector pulse width and generator
field control. If battery voltage is low, the PCM in-
creases injector pulse width (period of time that the
injector is energized).
BRAKE SWITCH—PCM INPUT
When the operator applies the brakes, the power-
train control module (PCM) receives an input from
the brake switch. When the PCM receives the brake
switch input a closed throttle input from the throttle
position sensor simultaneously, it recognizes a decel-
eration condition. The PCM adjusts injector pulse
width to compensate for the deceleration condition.
The brake switch input also disables torque convertor
clutch modulation.
If the PCM receives a brake switch input while the
speed control system is operating, the PCM disables
the speed control system.
CAMSHAFT POSITION SENSOR—PCM INPUT
The camshaft position sensor provides cylinder
identification to the powertrain control module (PCM)
(Fig. 3 or Fig. 4). The sensor generates pulses as
groups of notches on the camshaft sprocket pass un-
derneath it (Fig. 5 or Fig. 6). The PCM keeps track of
crankshaft rotation and identifies each cylinder by
the pulses generated by the notches on the camshaft
sprocket. Four crankshaft pulses follow each group of
camshaft pulses.
When the PCM receives two cam pulses followed by
the long flat spot on the camshaft sprocket, it knows
that the crankshaft timing marks for cylinder one are
next (on driveplate). When the PCM receives one
camshaft pulse after the long flat spot on the
sprocket, cylinder number two crankshaft timing
FUEL INJECTION—SYSTEM OPERATION 14 - 29