1999 DODGE RAM instrument cluster

circuit.
ONE GAUGE NOT OPERATING PROPERLY
NOTE: For connector terminal identification and wiring diagrams,
see BODY CONTROL COMPUTER - INTRODUCTION article. Perform
VERIFICATION TEST VER-1A after each repair.
CAUTION: Always turn ignition switch to OFF position prior to
disconnecting or connecting any module connector.
1) Push and hold RESET button while cycling ignition key; ON-
OFF-ON. Instrument cluster self-test will start. If inoperative gauge
reached proper calibration point, go to next step. If inoperative
gauge did not reach proper calibration point, replace instrument
cluster.
2) Stop instrument cluster self-test. If problem is with
speedometer, go to next step. If problem is with oil pressure gauge,
go to step 5). If problem is with temperature gauge, go to step 14).
If problem is with fuel level gauge, go to appropriate SELF-
DIAGNOSTICS article in ENGINE PERFORMANCE section and review
powertrain symptoms. If problem is with volt gauge, go to step 16). If
problem is with tachometer, go to step 18).
3) Using scan tool, select BODY, SYSTEMS TESTS then PCM
MONITOR. If scan tool displays PCM ACTIVE ON BUS, go to next step. If
scan tool does not display PCM ACTIVE ON BUS, go to appropriate
VEHICLE COMMUNICATIONS article.
4) Raise and support all wheels. Start engine and place gear
selector in drive. Using scan tool, select MIC, MONITORS then CCD BUS
ENGINE INFO. Read VSS. If vehicle speed on scan tool matches
speedometer, see appropriate ANTI-LOCK BRAKE article. If vehicle speed
on scan tool does not match speedometer, replace instrument cluster
circuit board.
5) Turn ignition on. If CHECK GAUGES light illuminated, go to
next step. If CHECK GAUGES light did not illuminate, go to step 11).
6) Turn ignition off. Inspect oil level. If oil level is
within specification, go to next step. If oil level is not within
specification, adjust oil level and retest.
7) Turn ignition on. Disconnect engine Oil Pressure Switch
(OPS) connector. OPS is located near bottom of distributor. If CHECK
GAUGES light went out, go to next step. If CHECK GAUGES light did not
go out, go to step 10).
8) Remove OPS. Connect mechanical oil pressure gauge to OPS
port. Start engine. If engine oil pressure at idle is 4 psi or more,
go to next step. If engine oil pressure at idle is less than 4 psi,
repair mechanical engine problem.
9) Run engine to reach normal operating temperature. If
engine oil pressure at idle is 4 psi or more, replace OPS. If engine
oil pressure at idle is less than 4 psi, repair mechanical engine
problem.
10) Turn ignition off. Disconnect PCM White connector C2. PCM
is located in engine compartment on right inner fender. Using an
external ohmmeter, measure resistance between ground and PCM Black
connector terminal No. 23 (Gray/Orange wire). If resistance is less
than 5 ohms, repair short to ground in Gray/Orange wire. If resistance
is 5 ohms or more, replace PCM.
11) Disconnect engine Oil Pressure Switch (OPS) connector.
OPS is located near bottom of distributor. Using an external ohmmeter,
measure resistance between ground and OPS connector Black/Light Blue
wire. If resistance is less than 5 ohms, go to next step. If
resistance is 5 ohms or more, repair open Black/Light Blue wire.
Black/Light Blue wire is a common sensor ground. If no other engine
sensors are failed, repair ground between sensor and splice. If

multiple engine sensors have failed, repair ground between splice and
PCM.
12) Connect jumper wire between OPS connector terminals. If
oil pressure warning indicator illuminates, replace OPS. If oil
pressure warning indicator does not illuminate, go to next step.
13) Do not remove jumper wire. Disconnect PCM Black connector
C2. PCM is located in engine compartment on right inner fender. Using
an external ohmmeter, measure resistance between ground and PCM White
connector C2 terminal No. 23 (Gray/Orange wire). If resistance is less\
than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open
Gray/Orange wire.
14) Check cooling system operation. If cooling system is
operating properly, go to next step. If cooling system is not
operating properly, repair engine cooling problem.
15) Using scan tool, select PCM MONITOR under SYSTEM TESTS.
If scan tool displays PCM ACTIVE ON BUS, system is currently
functioning properly. If scan tool does not display PCM ACTIVE ON BUS,
go to appropriate VEHICLE COMMUNICATIONS article.
16) Using scan tool, select MODULE ENGINE CONTROLLER. Read
PCM DTCs. If scan tool displays any charging system related DTCs, go
to appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section
and repair DTC as necessary. If scan tool does not display any
charging system related DTCs, go to next step.
17) Check charging system operation. If charging system is
operating properly, replace instrument cluster. If charging system is
not operating properly, repair engine charging problem.
18) Using scan tool, select BODY COMPUTER MONITORS. Read CCD
BUS ENGINE INFO. If scan tool displays engine RPM, replace instrument
cluster. If scan tool does not display engine RPM, replace PCM.
OVERHEAD CONSOLE CONCERNS
AVERAGE MPH/FUEL ECON INOPERATIVE OR WRONG (CMTC FAILS TO
RESPOND TO INSTRUMENT CLUSTER DIMMING, DISTANCE TO EMPTY
INOPERATIVE OR WRONG, ELAPSED TIME INOPERATIVE/WRONG, SWITCH
ON CMTC INOPERATIVE, TRIP ODOMETER INOPERATIVE/WRONG)
NOTE: If any listed symptoms exist, Compass Mini-Trip computer
(CMTC) is defective. Replace CMTC. Perform VERIFICATION TEST
VER- 1A after each repair.
CMTC SHOWS FAILED
NOTE: For connector terminal identification and wiring diagrams,
see BODY CONTROL COMPUTER - INTRODUCTION article. Perform
VERIFICATION TEST VER-1A after each repair.
Using scan tool, perform AUTO SELF TEST. If CMTC shows
failed, replace CMTC. If CMTC does not show failed, system is
currently functioning properly.
CMTC SEGMENTS FAIL TO LIGHT UP
NOTE: For connector terminal identification and wiring diagrams,
see BODY CONTROL COMPUTER - INTRODUCTION article. Perform
VERIFICATION TEST VER-1A after each repair.
Using scan tool, perform AUTO SELF TEST. If CMTC segments
fail to illuminate, replace CMTC. If CMTC segments all illuminate
properly, system is currently functioning properly.
INCORRECT READING BEYOND +/- 5

side of instrument panel, near transmission tunnel, and unplug heater
control panel-to-heater assembly vacuum harness connector. Disconnect
vacuum harness from center air duct.
2) On models equipped with A/T, unlock ignition switch. Set
parking brake and place gear selector lever in "L" position. If
equipped, set tilt steering column in lowest position.
3) On all models, remove screw securing cluster bezel to
instrument panel. See Fig. 8. Carefully pry bezel away from instrument
panel to disengage clips. Unplug connectors from cigarette lighter and
auxiliary power outlet.
4) Remove 4 bolts attaching heater control panel. Pull
control panel outward enough to disconnect wiring connector and vacuum
harness. Remove heater control panel. To install, reverse removal
procedure.
Fig. 8: Removing Cluster Bezel (Ram Pickup)
Courtesy of Chrysler Corp.
CAUTION: Use care when removing or installing instrument cluster bezel
so as not to damage trip odometer reset button. If trip
odometer reset button is damaged, instrument cluster must be
replaced.
Removal & Installation (Ram Van/Wagon)
1) Disconnect negative battery cable. Remove engine cover
from passenger compartment. Reach between upper dash panel engine
housing extension and bottom of instrument panel. Disconnect vacuum
harness connector located near left defroster outlet of distribution
duct.
2) On models equipped with A/T, unlock ignition switch. Set
parking brake and place gear selector lever in "L" position. If
equipped, set tilt steering column in lowest position. Carefully pry
bezel away from instrument panel to disengage clips. Pull bezel away
far enough to clear trip odometer reset button. Remove bezel.
3) Remove 3 bolts from heater control panel. Pull heater
control panel outward enough to disconnect electrical connectors and

Starters
Generator .................................. Generators & Regulators
Engine Performance
Power Distribution
Generic Electronic Module (GEM) ............... Body Control Modules\
Electronic Suspension
Glow Plug Relay ................................. Engine Performance
Glow Plugs ...................................... Engine Performance
Grounds ........................................ Ground Distribution
Headlight Door Module .............................. Headlight Doors
Headlight Relay .................................. Headlight Systems
Daytime Running Lights
Headlights ....................................... Headlight Systems
Daytime Running Lights
Heated Oxygen Sensor(s) (HO2S) .................. Engine Performan\
ce
Heated Windshield Control Module ................ Heated Windshields
Height Sensor ................................ Electronic Suspension
Horns ..................................... Steering Column Switches
Horn Relay ................................ Steering Column Switches
Idle Air Control (IAC) Motor/Valve .............. Engine Performance\
Ignition Coil(s) ................................ Engine Performance\
Ignition Key Lock Cylinder ....................... Anti-Theft System
Ignition Module ................................. Engine Performance
Ignition Switch ................................. Power Distribution
Engine Performance
Generators & Regulators
Starters
Illuminated Entry Module .............. Illumination/Interior Lights
Illumination Lights ................... Illumination/Interior Lights
Impact Sensor ............................. Air Bag Restraint System
Inertia Fuel Shutoff Switch ..................... Engine Performance
Inhibit Relay ............................................. Starters
Instrument Cluster ........................ Analog Instrument Panels
Intake Air Temperature (IAT) Sensor ............. Engine Performance\
Interior Lights ....................... Illumination/Interior Lights
Interlock Switch .......................................... Starters
Junction Block .................................. Power Distribution
Keyless Entry Receiver ........................ Remote Keyless Entry
Key Reminder Switch ....................................... Starters
Knock Sensor .................................... Engine Performance
Lamp Control Module ................................ Exterior Lights
License Plate Lamp ................................. Exterior Lights
Lighting Control Module ................... Lighting Control Modules
Anti-Theft System
Daytime Running Lights
Headlight Systems
Lower Relay .................................. Power Convertible Top
Malfunction Indicator Light (MIL) ............... Engine Performance\
Instrument Panels
Manifold Absolute Pressure (MAP) Sensor ......... Engine Performance\
Mass Airflow (MAF) Sensor ....................... Engine Performance\
Mega Fuse .................................. Generators & Regulators
Memory Seat/Mirror Module ........................... Memory Systems
Mirror Defogger ............................... Rear Window Defogger
Moon Roof Motor .................................... Power Moon Roof
Moon Roof Relay .................................... Power Moon Roof
Multi-Function Control Module ...................... Warning Systems
Neutral Safety Switch ..................................... Starters
Oil Level Switch ................................ Engine Performance
Oil Pressure Switch/Sending Unit .......... Analog Instrument Panels
Engine Performance
Overhead Console .................................. Overhead Console
Oxygen Sensor(s) (O2S) .......................... Engine Performan\
ce


IN STR UM EN T P A N EL - A N ALO G

1999 D odge P ic ku p R 1500
1999 ACCESSORIES & EQUIPMENT
CHRY - Analog Instrument Panels
Ram Pickup, Ram Van & Ram Wagon
DESCRIPTION & OPERATION
INSTRUMENT CLUSTER
All instrument cluster gauges are air core magnetic type.
Tachometer is optional. All gauges use data transferred on Chrysler
Collision Detection (CCD) bus. Instrument cluster incorporates a
Vacuum Fluorescent Display (VFD) for odometer display.
Brake warning light illuminates when ignition is on and
parking brake is applied. Brake warning light also illuminates if
brake hydraulic system failure occurs during service brake
application. Brake warning light bulb test occurs when ignition switch
is in START position.
Oil pressure warning light illuminates when engine oil
pressure is not sufficient to open oil pressure sending unit switch.
Oil pressure warning light bulb test occurs with ignition switch in
RUN position.
All instrument clusters include these analog gauges:
* Coolant Temperature Gauge
* Fuel Gauge
* Oil Pressure Gauge
* Speedometer
* Voltmeter
Instrument clusters include these indicator lights, if
vehicle is equipped with appropriate option:
* Air Bag
* Anti-Lock Brake System (ABS)
* Brake Warning
* Check Gauges
* Cruise On
* Headlight High Beam
* Low Fuel
* Low Washer Fluid
* CHECK ENGINE
* Overdrive Off
* Rear Wheel Anti-Lock (RWAL)
* Seat Belt Reminder
* Security
* Transmission Oil Temperature (A/T)
* Turn Signal
* Upshift (M/T)
* 4WD
SELF-DIAGNOSTIC SYSTEM
WARNING: Vehicle is equipped with an air bag system. To prevent air
bag deployment, disconnect negative battery cable and wait at
least 2 minutes before servicing instrument cluster. See
appropriate AIR BAG RESTRAINT SYSTEMS article.
CAUTION: When battery is disconnected, vehicle computer and memory

systems may lose memory data. Driveability problems may exist
until computer systems have completed a relearn cycle. See
COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION
before disconnecting battery.
NOTE: Testing of instrument panel and gauges requires using a scan
tool to check circuits connected to Body Control Module
(BCM). See appropriate BODY CONTROL COMPUTER TESTS article.
PRELIMINARY DIAGNOSIS
NOTE: There are 2 instrument cluster connectors. These connectors
look identical. Identify connectors by wire color. See WIRING
DIAGRAMS.
Ram Pickup
1) If CCD bus controlled indicator lights and gauges do not
operate, go to step 4). If indicator lights operate and all gauges do
not operate, go to next step.
2) Check for battery voltage between ground and both sides of
fuse No. 14 in junction block. If battery voltage exists on both
sides, go to next step. If battery voltage exists on one side only,
repair short circuit and replace fuse. If battery voltage does not
exist on both sides, locate and repair open circuit. See WIRING
DIAGRAMS.
3) Disconnect negative battery cable. Remove instrument
cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Connect
negative battery cable. Measure voltage between ground and terminal
No. 6 (Yellow wire) of instrument cluster connector C1. See Fig. 1. If
battery voltage is present, reinstall instrument cluster and go to
SELF-DIAGNOSTICS. If battery voltage is not present, repair open
circuit between fuse No. 14 in junction block and instrument cluster
connector C1.
4) Turn ignition on. Measure voltage between ground and both
sides of fuse No. 17 (10-amp) in junction block. If battery voltage
exists on both sides, go to next step. If battery voltage exists on
one side only, repair short circuit and replace fuse. If battery
voltage does not exist on both sides, repair open Dark Blue wire
between ignition switch and junction block.
5) Turn ignition off. Disconnect negative battery cable.
Reconnect instrument cluster. See INSTRUMENT CLUSTER under REMOVAL &
INSTALLATION. Connect negative battery cable. Turn ignition on. Set
parking brake and observe instrument cluster brake warning light. If
brake warning light is off, go to step 7). If brake warning light is
on, go to next step.
6) Turn ignition off. Turn parking lights on and adjust
instrument panel lights dimmer rheostat to full bright position. If
instrument panel lights are on, go to step 8). If instrument panel
lights are off, repair open ground circuit to instrument cluster
connector C1 terminal No. 4 (Black/Light Green wire) or No. 5
(Black/Orange wire). See WIRING DIAGRAMS.
7) Turn ignition off and disconnect negative battery cable.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL &
INSTALLATION. Connect negative battery cable. Turn ignition on.
Measure voltage between ground and instrument cluster connector C1
terminal No. 2 (Dark Blue/White wire). If battery voltage exists, go
to SELF-DIAGNOSTICS. If battery voltage does not exist, repair open
Dark Blue/White wire.
8) Turn ignition off. Disconnect negative battery cable.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL &
INSTALLATION. Using an ohmmeter, check continuity between ground and
instrument cluster connector C1 terminals No. 4 (Black/Light Green
wire) and No. 5 (Black/Orange wire). If continuity exists, go to SELF\
-

DIAGNOSTICS. If continuity does not exist, repair open Black/Light
Green or Black/Orange wire.
Fig. 1: Identifying Instrument Cluster Connector Terminals
Courtesy of Chrysler Corp.
Ram Van & Ram Wagon
1) If indicator lights operate, but all gauges are
inoperative, go to next step. If all gauges and CCD bus-controlled
indicator lights are inoperative, go to step 5).
2) Check fuse No. 12 (15-amp) in junction block. If fuse is
okay, go to next step. If any fuse is blown, repair short circuit and
replace fuse.
3) Measure voltage between ground and fuse No. 12 in junction
block. If battery voltage is present, go to next step. If battery
voltage is not present, repair open circuit.
4) Disconnect negative battery cable. Remove instrument

cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION.
Reconnect negative battery cable. Measure voltage between ground and
terminal No. 6 (Pink/White wire) of instrument cluster connector C1.
See Fig. 1 . If battery voltage is present, reinstall instrument
cluster and go to SELF- DIAGNOSTICS. If battery voltage is not
present, repair open circuit between fuse No. 12 (15-amp) in junction
block and instrument cluster connector C1 and go to next step.
5) Remove and inspect fuse No. 11 (10-amp) in junction block\
.
If fuse is okay, go to next step. If fuse is blown, locate and repair
cause of blown fuse. Install new fuse and recheck system operation.
6) Turn ignition on. Measure voltage between ground and power
side (Dark Blue/White wire) of fuse No. 11 (10-amp) in junction bloc\
k.
If battery voltage is present, go to step 8). If battery voltage is
not present, locate and repair open circuit to fuse No. 11. See WIRING
DIAGRAMS.
7) Turn ignition off and disconnect negative battery cable.
Install instrument cluster. Connect negative battery cable. Turn
ignition on. Set parking brake and observe instrument cluster brake
warning light. If brake warning light is on, go to next step. If brake
warning light is off, go to step 9).
8) Turn ignition off. Turn parking lights on and adjust
instrument panel lights dimmer rheostat to full bright position. If
instrument panel lights are on, go to step 10). If instrument panel
lights are off, repair instrument cluster illumination ground circuit
between instrument cluster connector C2 terminal No. 7 (Black wire)
and ground. See WIRING DIAGRAMS.
9) Turn ignition off and disconnect negative battery cable.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL &
INSTALLATION. Connect negative battery cable. Turn ignition on.
Measure voltage between ground and terminal No. 2 (Dark Blue/White
wire) at instrument cluster connector C1. If battery voltage is
present, go to SELF-DIAGNOSTICS. If battery voltage is not present,
repair open circuit between junction block fuse No. 11 and instrument
cluster.
10) Turn ignition off and disconnect negative battery cable.
Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL &
INSTALLATION. Check continuity between ground and terminal No. 4
(Black/Dark Green wire) at instrument cluster connector C1. If
continuity exists, go to SELF-DIAGNOSTICS. If continuity does not
exist, locate and repair open in ground circuit.
SELF-DIAGNOSTICS
1) With ignition off, press and hold trip odometer RESET
button while turning ignition switch to ON position. Continue to hold
RESET button until odometer window displays CHEC (about 10 seconds).
Release RESET button. If problem exists, system will display
Diagnostic Trouble Codes (DTC). See DIAGNOSTIC CODE CHART table. For
repairs of DTCs, see appropriate BODY CONTROL COMPUTER TESTS article.
DIAGNOSTIC TROUBLE (DTC) CODE CHART







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DTC Description  Correction 




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110 Cluster CPU, RAM Or EEPROM Fault  Replace Cluster 




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900 CCD Bus Inoperative Check CCD Bus Connections At

  Cluster; Check Cluster 

  Fuses; Check CCD Bus Bias;

  Check CCD Bus Voltage; 

  Check CCD Bus Terminations 




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920 Not Receiving VSS Message From PCM Check PCM Software Level;