Chrysler RAM TRUCK 2500 1994 Service Manual page 989

1 4 - 4 8 FUEL SYSTEM
•
• Engine coolant temperature
• Module timer
• Engine rpm
• MAP sensor
MANUAL TRANSMISSION
I f equipped with a manual transmission, pin #54
will control operation of the shift indicator lamp (if
equipped with lamp). The lamp is controlled by the
powertrain control module (PCM). The lamp illumi­
nates on the instrument panel to incicate when the
driver should shift to the next highest gear for best
fuel economy. The PCM will turn the lamp OFF after
3 to 5 seconds i f the shift of gears is not performed.
The lamp will remain off until vehicle stops acceler­
ating and is brought back to range of up-shift lamp
operation. This will also happen i f vehicle is shifted
into fifth gear.
The indicator lamp is normally illuminated when
the ignition switch is turned on and i t is turned off
when the engine is started up. With the engine run­
ning, the lamp is turned ON/OFF depending upon
engine speed and load.
OWERDRIVE SOLENOID—PCM PIN #§§—PCM
OUTPUT
AUTOMATIC TRANSMISSION
This circuit controls operation of the transmission
mounted overdrive solenoid (Fig. 35) used for over­
drive operation. The powertrain control module
(PCM) will determine when to engage and disengage
the solenoid by monitoring engine rpm versus output
voltage of the throttle position sensor. Also needed
are various inputs from:
• Engine coolant temperature
• Module timer
• Vehicle speed
• MAP sensor
SRI LAMP—PCM PIN #56—PCM OUTPUT
This circuit controls operation of the SRI lamp.
The instrument panel mounted service reminder
indicator (SRI) lamp was formerly referred to as the
emission maintenance reminder (EMR) lamp. I t is
used only on vehicles equipped with 5.9L V-8 or 8.0L
V-10 heavy duty cycle (HDC) engines. When the lamp
has been activated, certain service/maintenance must
be performed. For required service/maintenance
stated i n time or mileage, refer to Group 0, Lubrica­
tion and Maintenance. Also refer to Group 25, Emis­
sion Control System for information.
AUTOMATIC S H U T D O W N ( A S D ) S E N S E — P C M P I N
# 5 7 — P C M I N P U T
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The ASD relay is
located in the power distribution center (PDC). The
PDC is located next to the battery i n the engine com­
partment (Fig. 34). For the location of the relay
within the PDC, refer to PDC cover.
This relay is used to connect the oxygen sensor(s)
heater element, ignition coil(s), generator field wind­
ing and fuel injectors to the 12 volt + power supply.
The ASD relay is controlled by the PCM through
same circuit that the fuel pump relay is controlled.
This input is used only to sense that the ASD relay
is energized. I f the powertrain control module (PCM)
does not see 12 volts + at this input when the ASD
should be activated, i t will set a diagnostic trouble
code (DTC).
FUEL INJECTORS—PCM PIN #58—PCM OUTPUT
3 . 9 I / 5 . 2 1 / S . 9 L ENGINES
Pin #58 is used as the ground control circuit for the
fuel injector on cylinder #6 on 3.9L/5.2L/5.9L engines.
Refer to Fuel Injectors-PCM Pin # 1 3 - P C M Output
for information.
8 . 0 L V-10 ENGINE
Pin #58 is used as the ground control circuit for the
fuel injectors on cylinders #2 and #7 on the 8.0L V-10
engine (both injectors are fired simultaneously—one
cylinder on compression stroke and one cylinder on
exhaust stroke).
IDLE A I R CONTROL (IAC) M O T O R — P I N # 5 9 — P C M
OUTPUT
Pin #59 controls one of the circuits for operation of
the IAC motor. Refer to Idle A i r Control (IAC)
Motor—Pin #39—PCM Output for information.
IDLE AIR CONTROL (IAC) MOTOR—PIN #60—PCM
OUTPUT
Pin #60 controls one of the circuits for operation of
the IAC motor. Refer to Idle A i r Control (IAC)
M o t o r - P i n # 3 9 - P C M Output for information.
FUEL FILTER
A fuel tank mounted, combination, fuel filter/fuel
pressure regulator is used for all gasoline powered
engines. For information, refer to Fuel Filter/Fuel
Pressure Regulator i n the Fuel Delivery
System—Except Diesel section of this group.
FUEL PRESSURE REGULATOR
A fuel tank mounted, combination, fuel filter/fuel
pressure regulator is used for all gasoline powered
engines. For information, refer to Fuel Filter/Fuel
Pressure Regulator in the Fuel Delivery
System—Except Diesel section of this group.