Dodge RAM TRUCK 1500 1995 Service Manual page 621

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8W-31 TRANSMISSION CONTROLS 8W - 31 - 1
TRANSMISSION CONTROLS
OVERDRIVE SWITCH
Automatic transmission equipped vehicles may
have an overdrive switch. The operator disables or
enables overdrive when the switch is depressed.
The overdrive switch consists of a switch connected
to the Powertrain Control Module (PCM), an illumi­
nation lamp, and an overdrive ON/OFF indicator
lamp.
If overdrive is currently enabled, it is disabled
when the operator presses the overdrive switch. Con­
versely, if the operator already disabled overdrive, it
is enabled when the switch is pressed.
Circuit T6 from the overdrive switch connects to
cavity 10 of the PCM and provides the overdrive sig­
nal. Circuit Z3 provides ground for the switch.
The PCM turns the overdrive ON/OFF indicator
lamp ON or OFF by providing a ground for the lamp
on circuit T18. Power for the lamp is supplied by cir­
cuit F12 from the fuse block.
When the headlamps or parking lamps are ON, cir­
cuit E2 from fuse 13, a 5 amp, in the fuse block pow­
ers the illumination lamp in the overdrive switch.
Circuit E l from the headlamp switch feeds fuse 13.
Circuit Z3 provides ground for the illumination
lamp in the overdrive switch.
FOUR-WHEEL DRIVE INDICATOR
Power for the four-wheel drive indicator lamp is
supplied on circuit F14. Ground for the lamp is sup­
plied on circuit G107 to the switch. The ground is
passed through the CLOSED contacts in the switch
to circuit Zl.
PTO LAMP
Power for the Power Take-Off (PTO) indicator lamp
is supplied on circuit F14. Ground for the lamp is
supplied on circuit G107 to the switch. The ground is
passed through the CLOSED contacts in the switch
to circuit Zl.
OVERDRIVE. SOLENOID
The Powertrain Control Module (PCM) operates
the overdrive solenoid by providing a ground path on
circuit T60. Circuit T60 connects to PCM cavity 55.
Circuit F18 supplies battery voltage to the overdrive
solenoid.
TRANSMISSION OIL TEMPERATURE LAMP
Power for the transmission temperature sensor is
supplied on circuit T54 from the Powertrain Control
Module (PCM). Ground for the sensor is supplied on
circuit K4. This circuits is spliced and provides a
common sensor ground for various sensors used in
the engine control system.
Circuit T54 connects to cavity 42 of the PCM con­
nector, and circuit K4 connects to cavity 4 of the con­
nector.
The sensor is a variable resistor. When the PCM
determines that the transmission oil temperature is
above a predetermined level it supplies a ground
path for circuit G14. This circuit connects from the
PCM to the message center warning lamp.
Power for the lamp is supplied on circuit F14. The
F14 circuit is protected by a 15 amp fuse located in
cavity 12 of the fuse block and HOT in the START/
RUN position only.
Circuit G14 connects to cavity 31 of the PCM con­
nector on all engine applications, except for the 8.0L.
On the 8.0L the G14 circuit connects to cavity 36 of
the PCM connector.
HELPFUL INFORMATION
• Refer to the appropriate section of the service
manual or the diagnostic test procedures manual
DIAGRAM INDEi
Component Page
ABS Control Module 8W-31-3
Back-Up Lamp Switch 8W-31-5
Fuse 1 (PDC) 8W-31-2
Fuse 2 (PDC) .8W-31-4
Fuse 13 . . . .8W-31-2
Fuse 15 .8W-31-4
Fuse 18 8W-31-2
4X4 Switch . 8W-31-3
Headlamp Switch 8W-31-2
Ignition Switch 8W-31-4
Instrument Cluster 8W-31-2, 3
Park/Neutral Position Switch 8W-31-5
Power Distribution Center 8W-31-2
Powertrain Control Module 8W-31-2, 3
PTO Switch , . . 8W-31-3
RWAL Control Module . . . . . . . .8W-31-3
Transmission Overdrive Solenoid .8W-31-2
Transmission Overdrive Switch 8W-31-2
Transmission Temperature Sensor 8W-31-3