auto matic Transmission DODGE RAM 1500 1998 2.G Service Manual

the PCM or ECM indicating the percent tank full is
less than empty, the gauge needle is moved to the far
left end of the gauge scale and the low fuel indicator
is illuminated immediately. This message would indi-
cate that the fuel tank sender input to the PCM or
ECM is a short circuit.
²More Than Full Percent Tank Full Message
- Each time the cluster receives a message from the
PCM or ECM indicating the percent tank full is more
than full, the gauge needle is moved to the far left
end of the gauge scale and the low fuel indicator is
illuminated immediately. This message would indi-
cate that the fuel tank sender input to the PCM or
ECM is an open circuit.
²Communication Error- If the cluster fails to
receive a percent tank full message, it will hold the
gauge needle at the last indication about five seconds
or until the ignition switch is turned to the Off posi-
tion, whichever occurs first. After five seconds, the
cluster will move the gauge needle to the low end of
the gauge scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the fuel gauge needle will
be swept to several calibration points on the gauge
scale in a prescribed sequence in order to confirm the
functionality of the gauge and the cluster control cir-
cuitry.
On vehicles with a gasoline engine, the PCM con-
tinually monitors the fuel tank sending unit to deter-
mine the level of the fuel in the fuel tank. On
vehicles with a diesel engine, the ECM continually
monitors the fuel tank sending unit to determine the
level of the fuel in the fuel tank. The PCM or ECM
then sends the proper fuel level messages to the
instrument cluster. For further diagnosis of the fuel
gauge or the instrument cluster circuitry that con-
trols the gauge, (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING).
For proper diagnosis of the fuel tank sending unit,
the PCM, the ECM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the fuel gauge, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
GEAR SELECTOR INDICATOR
DESCRIPTION
An electronic automatic transmission gear selector
indicator is standard factory-installed equipment onthis model. The gear selector indicator information is
displayed in a Vacuum-Fluorescent Display (VFD)
unit. The VFD is soldered onto the cluster electronic
circuit board and is visible through a window with a
smoked clear lens located on the lower edge of the
speedometer gauge dial face of the cluster overlay.
The dark lens over the VFD prevents the indicator
from being clearly visible when it is not illuminated.
The gear selector indicator displays the following
characters from left to right: ªP,º ªR,º ªN,º ªD,º ª2,º
and ª1º (Fig. 18). Respectively, these characters rep-
resent the park, reverse, neutral, drive, second gear,
and first gear positions of the transmission gear
selector lever on the steering column. The VFD illu-
minates a rectangular box around the character that
represents the currently selected lever position.
The gear selector indicator characters and graphics
appear in the same blue-green color and at the same
lighting level as the odometer/trip odometer informa-
tion when illuminated by the instrument cluster elec-
tronic circuit board. During daylight hours (exterior
lamps Off) the gear selector indicator VFD is illumi-
nated at full brightness for clear visibility. At night
(exterior lamps are On) the VFD lighting level is
adjusted with the other cluster illumination lamps
using the panel lamps dimmer thumbwheel on the
headlamp switch. However, a ªParadeº mode position
of the panel lamps dimmer thumbwheel allows the
VFD to be illuminated at full brightness when the
vehicle is driven in daylight hours with the exterior
lamps turned On. The gear selector indicator VFD is
serviced as a unit with the instrument cluster.
OPERATION
The electronic gear selector indicator gives an indi-
cation to the vehicle operator of the transmission
gear that has been selected with the automatic trans-
mission gear selector lever. This indicator is con-
trolled by the instrument cluster circuit board based
upon cluster programming. The cluster circuitry
automatically configures itself for the proper trans-
mission and automatic transmission model based
upon the hard wired transmission range sensor mux
circuit input to the cluster. The gear selector indica-
tor information is displayed by a dedicated Vacuum
Fluorescent Display (VFD) unit on the instrument
cluster electronic circuit board, and the VFD will not
display the gear selector indicator information after
the ignition switch is turned to the Off position. The
instrument cluster circuitry configures the gear selec-
tor indicator VFD based upon the following inputs
from the transmission range sensor:
²Open Circuit- If the cluster is configured for
an automatic transmission and the transmission
range sensor mux circuit is open, the cluster circuitry
controls the gear selector indicator display based
Fig. 18 Gear Selector Indicator
DRINSTRUMENT CLUSTER 8J - 27
FUEL GAUGE (Continued)

upon electronic messages received from the electronic
Transmission Control Module (TCM) over the Pro-
grammable Communications Interface (PCI) data
bus. If the transmission range sensor mux circuit is
open and no electronic messages are received from
the TCM within two seconds, the instrument cluster
circuitry will not display any gear selector position
until the condition is resolved or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Resolved Circuit- If the transmission range
sensor mux circuit is resolved, the cluster circuitry
controls the gear selector indicator display based
upon the resistance value of the hard wired input
from the transmission range sensor. If the cluster is
configured for an automatic transmission with a
transmission range sensor input and detects a short
to ground or an open in the transmission range sen-
sor mux input, the instrument cluster circuitry will
not display any gear selector position in the VFD.
The VFD display for the short-to-ground and open
circuit conditions will continue until the condition is
resolved or until the ignition switch is turned to the
Off position, whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the gear selector indicator
VFD will display all of its characters at once during
the VFD portion of the test to confirm the function-
ality of the VFD and the cluster control circuitry.
On models with a TCM, the TCM continually mon-
itors the transmission range sensor, then sends the
proper gear selector indicator position messages to
the instrument cluster. On models without a TCM,
the instrument cluster continually monitors the hard
wired transmission range sensor multiplexed input.
For further diagnosis of the gear selector indicator or
the instrument cluster circuitry that controls this
function, (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). For fur-
ther diagnosis of the transmission range sensor on
models without a TCM, (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 42RE/TRANS-
MISSION RANGE SENSOR - DIAGNOSIS AND
TESTING) or (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 46RE/TRANSMISSION
RANGE SENSOR - DIAGNOSIS AND TESTING).
On models with a TCM, for proper diagnosis of the
transmission range sensor, the TCM, the PCI data
bus, or the electronic message inputs to the instru-
ment cluster that control the gear selector indicator,
a DRBIIItscan tool is required. Refer to the appro-
priate diagnostic information.HIGH BEAM INDICATOR
DESCRIPTION
A high beam indicator is standard equipment on
all instrument clusters (Fig. 19). The high beam indi-
cator is located near the upper edge of the instru-
ment cluster, between the tachometer and the
speedometer. The high beam indicator consists of a
stencil-like cutout of the International Control and
Display Symbol icon for ªHigh Beamº in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from
being clearly visible when the it is not illuminated. A
blue Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the icon to
appear in blue through the translucent outer layer of
the overlay when the indicator is illuminated from
behind by the LED, which is soldered onto the
instrument cluster electronic circuit board. The high
beam indicator is serviced as a unit with the instru-
ment cluster.
OPERATION
The high beam indicator gives an indication to the
vehicle operator whenever the headlamp high beams
are illuminated. This indicator is controlled by a
transistor on the instrument cluster circuit board
based upon cluster programming and a hard wired
multiplex input received by the cluster from the
headlamp beam select switch circuitry of the multi-
function switch on the washer/beam select switch
mux circuit. The high beam indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment cluster logic circuit, and that logic will allow
this indicator to operate whenever the instrument
cluster receives a battery current input on the fused
B(+) circuit. Therefore, the LED can be illuminated
regardless of the ignition switch position. The LED
only illuminates when it is provided a path to ground
by the instrument cluster transistor. The instrument
cluster will turn on the high beam indicator for the
following reasons:
²High Beam Headlamps-On Input- Each time
the cluster detects a high beam headlamps-on input
from the headlamp beam select switch circuitry of
the multi-function switch on the washer/beam select
switch mux circuit, the headlamp high beams and
the high beam indicator will be illuminated. The
headlamp high beams and the high beam indicator
remain illuminated until the cluster receives a high
beam headlamps-off input from the multi-function
switch, or until the exterior lamp load shedding (bat-
Fig. 19 High Beam Indicator
8J - 28 INSTRUMENT CLUSTERDR
GEAR SELECTOR INDICATOR (Continued)

tioned at the relative engine speed position on the
gauge scale until the engine stops running, or until
the ignition switch is turned to the Off position,
whichever occurs first.
²Communication Error- If the cluster fails to
receive an engine speed message, it will hold the
gauge needle at the last indication for about three
seconds, or until the ignition switch is turned to the
Off position, whichever occurs first. After three sec-
onds, the gauge needle will return to the left end of
the gauge scale.
²Actuator Test- Each time the cluster is put
through the actuator test, the tachometer needle will
be swept to several calibration points on the gauge
scale in a prescribed sequence in order to confirm the
functionality of the gauge and the cluster control cir-
cuitry.
On vehicles with a gasoline engine, the PCM con-
tinually monitors the crankshaft position sensor to
determine the engine speed. On vehicles with a die-
sel engine, the ECM continually monitors the engine
speed sensor to determine the engine speed. The
PCM or ECM then sends the proper engine speed
messages to the instrument cluster. For further diag-
nosis of the tachometer or the instrument cluster cir-
cuitry that controls the gauge, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
crankshaft position sensor, the engine speed sensor,
the PCM, the ECM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the tachometer, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
TOW/HAUL INDICATOR
DESCRIPTION
A tow/haul indicator is standard equipment on all
instrument clusters (Fig. 30). However, on vehicles
not equipped with the optional overdrive automatic
transmission, this indicator is electronically disabled.
The tow/haul indicator consists of the text ªTOW/
HAULº, which appears in the lower portion of the
odometer/trip odometer indicator Vacuum Fluores-
cent Display (VFD) unit. The VFD is soldered onto
the cluster electronic circuit board and is visible
through a window with a smoked clear lens located
on the lower edge of the tachometer gauge dial face
of the cluster overlay. The dark lens over the VFDprevents the indicator from being clearly visible
when it is not illuminated. The text ªTOW/HAULº
appear in an amber color and at the same lighting
level as the odometer/trip odometer information
when they are illuminated by the instrument cluster
electronic circuit board. The tow/haul indicator is ser-
viced as a unit with the VFD in the instrument clus-
ter.
OPERATION
The tow/haul indicator gives an indication to the
vehicle operator when the Off position of the tow/
haul switch has been selected, disabling the electron-
ically controlled overdrive feature of the automatic
transmission. This indicator is controlled by the
instrument cluster circuit board based upon cluster
programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The tow/haul indicator is
completely controlled by the instrument cluster logic
circuit, and that logic will only allow this indicator to
operate when the instrument cluster receives a bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the indicator will
always be off when the ignition switch is in any posi-
tion except On or Start. The indicator only illumi-
nates when it is switched to ground by the
instrument cluster circuitry. The instrument cluster
will turn on the tow/haul off indicator for the follow-
ing reasons:
²Tow/Haul Lamp-On Message- Each time the
cluster receives a tow/haul lamp-on message from the
PCM indicating that the Off position of the tow/haul
switch has been selected, the tow/haul indicator will
be illuminated. The indicator remains illuminated
until the cluster receives a tow/haul lamp-off mes-
sage from the PCM, or until the ignition switch is
turned to the Off position, whichever occurs first.
²Actuator Test- Each time the cluster is put
through the actuator test, the tow/haul indicator will
be turned on, then off again during the VFD portion
of the test to confirm the functionality of the VFD
and the cluster control circuitry.
The PCM continually monitors the tow/haul switch
to determine the proper outputs to the automatic
transmission. The PCM then sends the proper tow/
haul lamp-on and lamp-off messages to the instru-
ment cluster. For further diagnosis of the tow/haul
indicator or the instrument cluster circuitry that con-
trols the indicator, (Refer to 8 - ELECTRICAL/IN-
STRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the overdrive con-
trol system, the PCM, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that
control the tow/haul indicator, a DRBIIItscan tool is
Fig. 30 Tow/Haul Indicator
DRINSTRUMENT CLUSTER 8J - 39
TACHOMETER (Continued)

required. Refer to the appropriate diagnostic infor-
mation.
TRANS TEMP INDICATOR
DESCRIPTION
A transmission over-temperature indicator is stan-
dard equipment on all instrument clusters (Fig. 31).
However, on vehicles not equipped with an optional
automatic transmission, this indicator is electroni-
cally disabled. The transmission over-temperature
indicator is located on the left side of the instrument
cluster, to the left of the fuel gauge. The transmission
over-temperature indicator consists of a stencil-like
cutout of the words ªTRANS TEMPº in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from
being clearly visible when it is not illuminated. A red
Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the ªTRANS
TEMPº text to appear in red through the translucent
outer layer of the overlay when the indicator is illu-
minated from behind by the LED, which is soldered
onto the instrument cluster electronic circuit board.
The transmission over-temperature indicator is ser-
viced as a unit with the instrument cluster.
OPERATION
The transmission over-temperature indicator gives
an indication to the vehicle operator when the trans-
mission fluid temperature is excessive, which may
lead to accelerated transmission component wear or
failure. This indicator is controlled by a transistor on
the instrument cluster circuit board based upon clus-
ter programming and electronic messages received by
the cluster from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus. The transmission over-tem-
perature indicator Light Emitting Diode (LED) is
completely controlled by the instrument cluster logic
circuit, and that logic will only allow this indicator to
operate when the instrument cluster receives a bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the LED will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the transmission over-temperature indicator
for the following reasons:²Bulb Test- Each time the ignition switch is
turned to the On position the transmission over-tem-
perature indicator is illuminated for about two sec-
onds as a bulb test.
²Trans Over-Temp Lamp-On Message- Each
time the cluster receives a trans over-temp lamp-on
message from the PCM indicating that the transmis-
sion fluid temperature is 135É C (275É F) or higher,
the indicator will be illuminated and a single chime
tone is sounded. The indicator remains illuminated
until the cluster receives a trans over-temp lamp-off
message from the PCM, or until the ignition switch
is turned to the Off position, whichever occurs first.
The chime tone feature will only repeat during the
same ignition cycle if the transmission over-tempera-
ture indicator is cycled off and then on again by the
appropriate trans over-temp messages from the PCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the transmission over-tem-
perature indicator will be turned on, then off again
during the bulb check portion of the test to confirm
the functionality of the LED and the cluster control
circuitry.
The PCM continually monitors the transmission
temperature sensor to determine the transmission
operating condition. The PCM then sends the proper
trans over-temp lamp-on or lamp-off messages to the
instrument cluster. If the instrument cluster turns on
the transmission over-temperature indicator due to a
high transmission oil temperature condition, it may
indicate that the transmission and/or the transmis-
sion cooling system are being overloaded or that they
require service. For further diagnosis of the trans-
mission over-temperature indicator or the instrument
cluster circuitry that controls the LED, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
transmission temperature sensor, the PCM, the PCI
data bus, or the electronic message inputs to the
instrument cluster that control the transmission
over-temperature indicator, a DRBIIItscan tool is
required. Refer to the appropriate diagnostic infor-
mation.
TURN SIGNAL INDICATOR
DESCRIPTION
Two turn signal indicators, one right and one left,
are standard equipment on all instrument clusters
(Fig. 32). The turn signal indicators are located near
Fig. 31 Transmission Overtemp Indicator
Fig. 32 Turn Signal Indicators
8J - 40 INSTRUMENT CLUSTERDR
TOW/HAUL INDICATOR (Continued)

(2) Install the lamp back plate onto the tail lamp
unit.
(3) Install the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/TAIL
LAMP UNIT - INSTALLATION).
(4) Reconnect the negative battery cable.
INSTALLATION - WITHOUT CARGO BOX
(1) Install the backup lamp bulb into the backup
lamp socket by pushing inward and rotating it clock-
wise.
NOTE: Install the tail lamp lens with the clear por-
tion (back-up lens) at the top of the housing. Make
sure that the gasket is correctly in place and not
twisted or torn.
(2) Position the tail lamp lens and gasket onto the
tail lamp unit.
NOTE: Do not overtighten the tail lamp lens screws
or damage to the tail lamp lens may result.
(3) Install the four screws that secure the tail
lamp lens to the tail lamp unit. Tighten the screws
securely.
(4) Reconnect the negative battery cable.
BACKUP LAMP SWITCH
DESCRIPTION
Vehicles equipped with a manual transmission
have a normally open, spring-loaded plunger typeback-up lamp switch (Fig. 2). The backup lamp
switch is located in a threaded hole on the side of the
manual transmission housing. The backup lamp
switch has a threaded body and a hex formation near
the plunger end of the switch, and an integral con-
nector at the opposite end of the switch. When
installed, only the connector and the hex formation
are visible on the outside of the transmission hous-
ing. Vehicles with an optional electronic automatic
transmission have a Transmission Range Sensor
(TRS) that is used to perform several functions,
including that of the backup lamp switch. The TRS is
described in further detail elsewhere in this service
information. The backup lamp switch cannot be
adjusted or repaired and, if faulty or damaged, the
entire switch unit must be replaced.
OPERATION
The backup lamp switch controls the flow of bat-
tery voltage to the backup lamp bulbs through an
output on the back-up lamp feed circuit. The switch
plunger is mechanically actuated by the gearshift
mechanism within the transmission, which will
depress the switch plunger and close the switch con-
tacts whenever the reverse gear has been selected.
The switch receives battery voltage through a fuse in
the Integrated Power Module (IPM) on a fused igni-
tion switch output (run) circuit whenever the ignition
switch is in the On position. A take out of the engine
wire harness connects the backup lamp switch to the
vehicle electrical system. The backup lamp switch
and circuits can be tested using conventional diag-
nostic tools and methods.
DIAGNOSIS AND TESTING - BACKUP LAMP
SWITCH
(1) Disconnect and isolate the battery negative
cable.
(2) Raise and support the vehicle.
(3) Locate and disconnect the engine wire harness
connector for the backup lamp switch.
(4) Check for continuity between the two terminal
pins in the backup lamp switch connector.
(a) With the gear selector lever in the Reverse
position, there should be continuity.
(b) With the gear selector lever in any position
other than Reverse, there should be no continuity.
Fig. 2 Backup Lamp Switch - Typical
1 - MANUAL TRANSMISSION
2 - BACKUP LAMP SWITCH
3 - ENGINE WIRE HARNESS
8L - 8 LAMPS/LIGHTING - EXTERIORDR
BACKUP LAMP (Continued)

appears,AUTO UNLOCK ON EXIT?- The options
again include Yes and No. The default is No. When
Yes is selected, following each Auto Door Lock event
all doors will automatically unlock when the driver
door is opened, if the vehicle is stopped and the
transmission gear selector is in Park or Neutral. The
Auto Door Unlock event will only occur once follow-
ing each Auto Door Lock event.
²REMOTE UNLOCK- The options include
Driver Door 1st and All Doors. The default is Driver
Door 1st. When Diver Door 1st is selected, only the
driver door unlocks when the Unlock button of the
Remote Keyless Entry (RKE) transmitter is
depressed once. The Unlock button of the RKE trans-
mitter must be depressed twice to unlock all doors.
When All Doors is selected, all doors unlock when the
Unlock button of the RKE transmitter is depressed
once.
²SOUND HORN ON LOCK?- The options
include On and Off. The default is No. When Yes is
selected, a short horn chirp will provide an audible
confirmation when the RKE receiver recognizes a
valid Lock signal from an RKE transmitter. When No
is selected, no horn chirp will occur with the RKE
Lock event. This feature may be selected indepen-
dent of theFLASH LIGHTS WITH LOCKS?pro-
grammable feature.
²FLASH LIGHTS WITH LOCKS?- The options
include Yes and No. The default is Yes. When Yes is
selected, a single flash of the hazard warning lamps
will provide an optical confirmation when the RKE
receiver recognizes a valid Lock signal from an RKE
transmitter, and two flashes of the same lamps will
occur when the RKE receiver recognizes a valid
Unlock signal from an RKE transmitter. When No is
selected, no lamp flash will occur with the RKE Lock
or Unlock event. This feature may be selected inde-
pendent of theSOUND HORN ON LOCK?pro-
grammable feature.
²HEADLAMP DELAY =- The options include
Off, 30 Sec, 60 Sec, and 90 Sec. The default is 90 Sec.
When a time interval is selected, the headlamps will
remain on for that length of time when the head-
lamps are turned off after the ignition is turned off,
or if the Auto mode is selected on vehicles with the
Auto Headlamps option. When Off is selected, the
headlamp delay feature is disabled.
²TRAIN REMOTE- When this feature is
selected the driver can choose to train up to four
remote keyless entry transmitters. The options
include Yes and No. The default is No. When Yes is
selected and the MENU button is pressed the EVIC
will display ªPRESS REMOTE LOCK & UNLOCK
THEN PRESS UNLOCKº, followed by a chime to
indicate the training sequence can commence. You
have approximately 30 seconds to train up to fourtransmitters, after each transmitter is trained a
chime will sound indicating that the training was
successful. If remote link to memory is ªYESº , the
first transmitter trained will be associated with
memory setting 1 and the second transmitter trained
will be associated with memory setting 2. Additional
transmitters will not be associated with a memory
setting. When you have finished training the trans-
mitters, press the menu button again and the EVIC
will display ªTRAIN DONE ªXº TRAINED. If no
transmitters are trained within approximately 30
seconds the EVIC will display ªTRAIN TIMEOUTº.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the overhead console from the headlin-
er.(Refer to 8 - ELECTRICAL/OVERHEAD CON-
SOLE - REMOVAL).
(3) Disconnect the EVIC module electrical connec-
tor. Depress the retaining tab and pull straight
apart.
(4) Remove the screws holding the EVIC module in
the overhead console (Fig. 6).
(5) Remove EVIC module from console assembly.
INSTALLATION
(1) Position the EVIC module in the overhead con-
sole.
Fig. 6 OVERHEAD CONSOLE MODULE REMOVAL
1 - ELECTRONIC VEHICLE INFORMATION MODULE
2 - OVERHEAD CONSOLE
DRMESSAGE SYSTEMS 8M - 9
ELECTRONIC VEHICLE INFO CENTER (Continued)

(2) Disconnect wire harness connector to power
mirror switch (Fig. 1).
(3) Using two jumper wires:
²Connect one to a 12 volt source
²Connect the other to a good body ground
²Refer to the Mirror Motor Test Chart for proper
wire connections at the switch connector
MIRROR MOTOR TEST CHART
12 VOLTS GROUND MIRROR REACTION
SWITCH CONNECTOR RIGHT LEFT
PIN 1 PIN 2 - UP
PIN 6 PIN 2 - LEFT
PIN 2 PIN 1 - DOWN
PIN 2 PIN 6 - RIGHT
PIN 7 PIN 2 UP -
PIN 4 PIN 2 LEFT -
PIN 2 PIN 7 DOWN -
PIN 2 PIN 4 RIGHT -
(4) If results shown in table are not obtained,
check for open or shorted circuit. Replace mirror
assembly as necessary.
AUTOMATIC DAY / NIGHT
MIRROR
DESCRIPTION
The automatic day/night mirror uses a thin layer
of electrochromic material between two pieces of con-
ductive glass to make up the face of the mirror.
When the mirror switch is in the On position, two
photocell sensors are used by the mirror circuitry to
monitor external light levels and adjust the reflec-
tance of the mirror.
OPERATION
The ambient photocell sensor is located on the for-
ward-facing (windshield side) of the rear view mirror
housing, and detects the ambient light levels outside
of the vehicle. The headlamp photocell sensor is
located inside the rear view mirror housing behind
the mirror glass and faces rearward, to detect the
level of the light being received at the rear window
side of the mirror. When the circuitry of the auto-
matic day/night mirror detects that the difference
between the two light levels is too great (the light
level received at the rear of the mirror is much
higher than that at the front of the mirror), it begins
to darken the mirror.
The automatic day/night mirror circuitry also mon-
itors the transmission using an input from the
backup lamp circuit. The mirror circuitry is pro-
grammed to automatically disable its self-dimming
feature whenever it senses that the transmission
backup lamp circuit is energized.
The automatic day/night mirror is a completely
self-contained unit and cannot be repaired. If faulty
or damaged, the entire mirror assembly must be
replaced.
DIAGNOSIS AND TESTING - AUTOMATIC DAY /
NIGHT MIRROR
For complete circuit diagrams, refer to the appro-
priate wiring information.
(1) Check the fuse in the Integrated Power Module
(IPM). If OK, go to Step 2. If not OK, repair the
shorted circuit or component as required and replace
the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fuse in the IPM. If
OK, go to Step 3. If not OK, repair the open circuit to
the ignition switch as required.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Unplug the wire harness connector from the auto-
matic day/night mirror (Fig. 2). Connect the battery
negative cable. Turn the ignition switch to the On
position. Check for battery voltage at the fused igni-
tion switch output (run/start) circuit cavity of the
automatic day/night mirror wire harness connector. If
OK, go to Step 4. If not OK, repair the open circuit to
the IPM as required.
(4) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Check for continuity between the ground circuit cav-
ity of the automatic day/night mirror wire harness
connector and a good ground. There should be conti-
nuity. If OK, go to Step 5. If not OK, repair the cir-
cuit to ground as required.
Fig. 1 POWER MIRROR SWITCH CONNECTOR
DRPOWER MIRRORS 8N - 11
POWER MIRRORS (Continued)

(5) Connect the battery negative cable. Turn the
ignition switch to the On position. Set the parking
brake. Place the transmission gear selector lever in
the Reverse position. Check for battery voltage at the
backup lamp switch output circuit cavity of the auto-
matic day/night mirror wire harness connector. If
OK, go to Step 6. If not OK, repair the open circuit
as required.
(6) Turn the ignition switch to the Off position.
Disconnect the battery negative cable. Plug in the
automatic day/night mirror wire harness connector.
Connect the battery negative cable. Turn the ignition
switch to the On position. Place the transmission
gear selector lever in the Neutral position. Place the
mirror switch in the On (the LED in the mirror
switch is lighted) position. Cover the forward facing
ambient photocell sensor to keep out any ambient
light.NOTE: The ambient photocell sensor must be cov-
ered completely, so that no light reaches the sen-
sor. Use a finger pressed tightly against the sensor,
or cover the sensor completely with electrical tape.
(7) Shine a light into the rearward facing head-
lamp photocell sensor. The mirror glass should
darken. If OK, go to Step 8. If not OK, replace the
faulty automatic day/night mirror unit.
(8) With the mirror glass darkened, place the
transmission gear selector lever in the Reverse posi-
tion. The mirror should return to its normal reflec-
tance. If not OK, replace the faulty automatic day/
night mirror unit.
REMOVAL
For removal procedures, (Refer to 23 - BODY/IN-
TERIOR/REAR VIEW MIRROR - REMOVAL).
POWER MIRROR SWITCH
DIAGNOSIS AND TESTING - POWER MIRROR
SWITCH
The power mirror switch is included with the
Driver Door Module. (Refer to 8 - ELECTRICAL/
POWER LOCKS/DOOR MODULE - DIAGNOSIS
AND TESTING).
REMOVAL
The power mirror switch is included with the
Driver Door Module. (Refer to 8 - ELECTRICAL/
POWER LOCKS/DOOR MODULE - REMOVAL).
SIDEVIEW MIRROR
REMOVAL
(Refer to 23 - BODY/EXTERIOR/SIDE VIEW MIR-
ROR - REMOVAL).
Fig. 2 Automatic Day/Night Mirror
1 - REAR FACING SENSOR
2 - CONNECTOR
3 - FORWARD FACING SENSOR
4 - SWITCH
8N - 12 POWER MIRRORSDR
AUTOMATIC DAY / NIGHT MIRROR (Continued)

If the stored DTC information is successfully erased,
go to Step 9.
(9) Turn the ignition switch to the Off position for
about fifteen seconds, and then back to the On posi-
tion. Observe the airbag indicator in the instrument
cluster. It should illuminate for six to eight seconds,
and then go out. This indicates that the supplemen-
tal restraint system is functioning normally and that
the repairs are complete. If the airbag indicator fails
to light, or lights and stays on, there is still an active
supplemental restraint system fault or malfunction.
Refer to the appropriate diagnostic information to
diagnose the problem.
ACM COVER
REMOVAL
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be removed to access the ACM for service.
(Refer to 23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry each side of the ACM
cover away from the instrument panel at each side of
the center bracket on the floor panel transmission
tunnel far enough to disengage the two snap clip
retainers from the instrument panel receptacles (Fig.
6).
(3) Remove the ACM cover from the instrument
panel.
INSTALLATION
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be reinstalled following ACM service. (Refer
to 23 - BODY/INTERIOR/FLOOR CONSOLE -
INSTALLATION).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Position the ACM cover to the instrument
panel (Fig. 6).
(2) Align the snap clip retainer on each side of the
ACM cover with the instrument panel receptacle at
each side of the center bracket on the floor panel
transmission tunnel.
(3) Using hand pressure, press firmly and evenly
on the outside of the ACM cover over each snap clip
retainer location until each retainer is fully engaged
in its instrument panel receptacle.
(4) Reconnect the battery negative cable.
Fig. 6 ACM Cover Remove/Install
1 - INSTRUMENT PANEL RECEPTACLE (2)
2 - ACM COVER
8O - 10 RESTRAINTSDR
RESTRAINTS (Continued)

AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is also some-
times referred to as the Occupant Restraint Control-
ler (ORC) (Fig. 7). The ACM is concealed below the
instrument panel center stack in the passenger com-
partment of the vehicle, where it is secured by three
screws to a stamped steel mounting bracket welded
onto the top of the floor panel transmission tunnel
just forward of the instrument panel center support
bracket. Concealed within a hollow in the center of
the die cast aluminum ACM housing is the electronic
circuitry of the ACM which includes a microproces-
sor, an electronic impact sensor, an electronic safing
sensor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ACM housing with four screws to enclose and protect
the internal electronic circuitry and components.
An arrow printed on the label on the top of the
ACM housing provides a visual verification of the
proper orientation of the unit, and should always be
pointed toward the front of the vehicle. The ACM
housing has integral mounting flanges on three cor-
ners. The mounting flange to the left of the connector
receptacle has an integral locating pin on its lower
surface. Both left side flanges have round mounting
holes, while the flange on the right side has a slotted
mounting hole. A molded plastic electrical connector
with two receptacles, one containing twenty-four ter-
minal pins and the other containing thirty-two termi-
nal pins, exits the rearward facing side of the ACM
housing. These terminal pins connect the ACM to the
vehicle electrical system through two dedicated takeouts and connectors of the instrument panel wire
harness.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. In addi-
tion, there are unique versions of the ACM for light
and heavy-duty models, and for vehicles with or
without the optional side curtain airbags. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault, or in some
cases for the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
In standard cab models, the ACM also monitors a
resistor multiplexed input from the passenger airbag
on/off switch and provides a control output for the
Off indicator in the switch through a passenger air-
bag indicator driver circuit. If the passenger airbag
on/off switch is set to the Off position, the ACM turns
on the passenger airbag on/off switch Off indicator
and will internally disable the passenger airbag from
being deployed. The ACM also turns on the on/off
switch Off indicator for about seven seconds each
time the ignition switch is turned to the On position
as a bulb test. Following the bulb test, the ACM con-
trols the status of the Off indicator based upon the
Fig. 7 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - LABEL
4 - CONNECTOR RECEPTACLE (2)
DRRESTRAINTS 8O - 11