Dodge RAM TRUCK 1500 1995 Service Manual page 1118

14 - 3 6 COMPONENT DESCRIPTION/SYSTEM OPERATION—EXCEPT DIESEL
B R
: GENERATOR
COOLANT
TEMPERATURE
SENSOR
J9314-78
Fig. 8 Coolant Temperature Sensor—3.9L V-6 or
5.2/5.9L V-8 Engines—Typical
^ ^ ^ ' ^ ^ ^ ^ X ^ ^ V
TEMP. GAUGE
^
ENGINE COOLANT TEMP. SENSOR I
5 ! ^ ^ ? l f £
R
J ^ ; ~
J948D-9
Fig. 9 Coolant Temperature Sensor—8.0L V-10
Engine
BATTERY TEMPERATURE SENSOR
This input is internal to the powertrain control
module (PCM). A thermistor located within the
PCM's printed circuit board is used to sense under­
hood temperature. This temperature is used to vary
the battery charging rate in relationship to the tem­
perature.
SENSOR RETURN—PCM PIN #4—PCM INPUT
Sensor Return provides a low noise ground refer­
ence for all system sensors.
FIVE VOLT POWER—PCM PIN #6—PCM INPUT
This circuit supplies approximately 5 volts to power
the MAP and TPS sensors.
EIGHT VOLT POWER—PCM PIN #7—PCM INPUT
This circuit supplies approximately 8 volts to power
the vehicle speed, camshaft position and crankshaft
position sensors.
IGNITION CIRCUIT SENSE—PCM PIN #9—PCM
INPUT
The ignition circuit sense input tells the powertrain
control module (PCM) the ignition switch has ener­
gized the ignition circuit. Refer to the wiring dia­
grams for circuit information.
OVERDRIVE/OVERRIDE SWITCH—PCM PIN
#10—PCM INPUT
On vehicles equipped with an automatic transmis­
sion and overdrive, the powertrain control module
(PCM) regulates the 3-4 overdrive up-shift and down­
shift through the overdrive solenoid. This solenoid is
located in the transmission. An overdrive/override
push-button switch is located on the instrument
panel.
The PCM circuit for overdrive is controlled by in­
puts from the engine coolant temperature sensor and
vehicle speed sensor. If coolant temperature and ve­
hicle speed are not within the preset PCM specifica­
tions, the PCM will not allow the transmission to
shift into overdrive. These preset PCM specifications
must be met before the push-button switch will be al­
lowed to control overdrive operation.
The overdrive/override push-button switch is nor­
mally closed (overdrive allowed) when the lamp is
not illuminated. It opens (overdrive not allowed)
when the operator presses the switch and the lamp is
illuminated. The switch will revert to its normally
closed position (lamp off) each time the ignition
switch in turned on. The transmission downshifts if
the operator presses the override switch while in
overdrive.
Also refer to: Overdrive Solenoid—PCM Pin #55—
PCM Output, Transmission Temperature Warning
Lamp-PCM Pin #31-PCM Output and Transmis­
sion Temperature Sensor—PCM Pin #42—PCM Input
for additional information.
Refer to Group 21 for more transmission informa­
tion.
POWER GROUND—PCM PIN #11
Provides a common ground for power devices (sole­
noid and relay devices).
POWER GROUND—PCM PIN #12
Provides a common ground for power devices (sole­
noid and relay devices).
FUEL INJECTORS—PCM PIN #13—PCM OUTPUT
3.BU5.2L/B.BL ENGINES
Pin #13 is used as the ground control circuit for the
fuel injector on cylinder #4 on 3.9L/5.2L/5.9L engines.
The injectors (Fig. 10) are energized individually in
a sequential order by the powertrain control module
(PCM). The PCM will adjust injector pulse width by