1999 DODGE RAM can bus


A/C S YSTE M G EN ER AL S ER VIC IN G
1999 D odge P ic ku p R 1500
1999 GENERAL SERVICING
A/C System General Servicing
All Models
USING R-134a REFRIGERANT
HANDLING/SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
is colorless and invisible as a gas. Refrigerant is heavier than
oxygen and will displace oxygen in a confined area. Avoid breathing
refrigerant vapors. Exposure may irritate eyes, nose and throat.
2) Always wear eye protection when working around A/C system
and refrigerant. The system's high pressure can cause severe injury to
eyes and skin if a hose were to burst. If necessary, wear rubber
gloves or other protective clothing.
3) Refrigerant evaporates quickly when exposed to atmosphere,
freezing anything it contacts. If liquid refrigerant contacts eyes or
skin (frostbite), DO NOT rub eyes or skin. Immediately flush affected
area with cool water for 15 minutes and consult a doctor or hospital.
4) Never use R-134a in combination with compressed air for
leak testing. Pressurized R-134a in the presence of oxygen (air
concentrations greater than 60 percent by volume) may form a
combustible mixture. DO NOT introduce compressed air into R-134a
containers (full or empty), A/C system components, or service
equipment.
5) DO NOT expose A/C system components to high temperatures
(steam cleaning for example), as excessive heat will cause refrigerant\
system pressure to increase. Never expose refrigerant directly to open
flame. If refrigerant needs to be warmed, place bottom of refrigerant
tank in warm water. Water temperature MUST NOT exceed 125
F (52C).
CAUTION: When R-134a is exposed to an open flame, drawn into engine,
or detected with a Halide (propane) leak tester, a poisonous
gas is formed. Keep work areas well ventilated.
6) Use care when handling refrigerant containers. DO NOT
drop, strike, puncture, or incinerate containers. Use DOT 4BW or DOT
4BA approved refrigerant containers.
7) Never overfill refrigerant containers. The safe filling
level of a refrigerant container MUST NOT exceed 60\% of the
container's gross weight rating. Store refrigerant containers at
temperatures less than 125
F (52C).
8) R-134a refrigerant is sold and stored in 30- or 50-pound
Light Blue containers, while Freon (R-12) is stored in White colored
containers.
9) Refrigerant R-12 and R-134a must never be mixed, as they
and their desiccants and lubricants are not compatible. If the
refrigerants are mixed, system cross-contamination or A/C system
component failure may occur. Always use separate servicing and
refrigerant recovery/recycling equipment.
10) Read and follow equipment manufacturer's instructions for
all service equipment to be used. The Material Safety Data Sheet
(MSDS), provided by refrigerant manufacturer/supplier, contains
valuable information regarding the safe handling of refrigerants.
IDENTIFYING R-134a SYSTEMS & COMPONENTS


AN TI- T H EFT S YSTE M

1999 D odge P ic ku p R 1500
1999 ACCESSORIES & EQUIPMENT
CHRY - Anti-Theft Systems
Ram Pickup, Ram Van & Ram Wagon
DESCRIPTION
The Vehicle Theft Security System (VTSS) provides an engine
no-run feature, flashes headlights and sounds horn if any door or hood
is opened without using key or remote keyless entry transmitter, or if
battery cables are disconnected then reconnected when system is
activated.
Anti-theft system is controlled by Central Timer Module
(CTM). CTM is located under driver's side of dash panel, right of
steering column. If CTM is faulty, CTM cannot be repaired and must be
replaced.
VTSS is also equipped with a power-up mode. If battery is
disconnected or looses power while VTSS is armed, VTSS system remains
armed when power is restored. A temper alert signal is sounded on
vehicle entry if VTSS was triggered while away from vehicle. Horn will
sound 3 times alerting owner VTSS was triggered.
OPERATION
ARMING PROCEDURE (PASSIVE)
Remove key from ignition. Ensure headlights are off. Lock
doors while open, using power lock switch. Power lock switch will not
operate with key in ignition or headlights on while door is open.
Vehicle Theft Security System (VTSS) will not arm using key in lock
cylinder or mechanical lock button. While system is arming, SECURITY
light will flash rapidly for 15 seconds. Opening any door or turning
the ignition key while light is flashing will abort arming process.
Once arming process is complete, SECURITY light will go out.
ARMING PROCEDURE (ACTIVE)
Pressing Remote Keyless Entry (RKE) transmitter LOCK button
will actively arm Vehicle Theft Security System (VTSS). All doors must\
be closed and ignition switch in OFF position. While system is arming,
SECURITY light will flash rapidly for 15 seconds. Opening any door or
turning the ignition key while light is flashing will abort arming
process. Once arming process is complete, SECURITY light will go out.
DISARMING
Vehicle Theft Security System (VTSS) can be disarmed 2 ways:
unlock vehicle using key in any door and pressing remote keyless entry
transmitter UNLOCK button. If alarm has been set off, either method
can be used to disarm and shut-off horn.
CENTRAL TIMER MODULE (CTM)
Central Timer Module (CTM) is Vehicle Theft Security System
(VTSS) processor. CTM uses the data bus network to allow sharing and
reporting of sensor information. If a door ajar sensor is opened while
VTSS is set, a signal is sent to flash headlights and sound horn. PCM
is also notified through bus network to enable engine no-run feature.

BO DY C O NTR O L C O M PU TE R

1999 D odge P ic ku p R 1500
1999 ACCESSORIES & EQUIPMENT
CHRY - Body Control Computer Tests
Ram Pickup
NOTE: See BODY CONTROL COMPUTER - INTRODUCTION article before
proceeding with following test. Body control computer in RWD
trucks is the Central Timer Module (CTM).
SYMPTOM IDENTIFICATION
IDENTIFYING VEHICLE EQUIPMENT & SYSTEM PROBLEMS
NOTE: For connector terminal identification wiring diagrams, see
BODY CONTROL COMPUTER - INTRODUCTION article.
NOTE: Perform a visual inspection before proceeding with this test.
Ensure battery is fully charged.
1) Connect scan tool to Data Link Connector (DLC). DLC is a
16-pin connector located under left side of dash, to left of steering
wheel. Turn ignition switch to ON position. If scan tool display is
not blank, go to next step. If scan tool display is blank, see
appropriate VEHICLE COMMUNICATIONS article.
2) Using scan tool, select SYSTEM MONITORS, then CCD BUS
TEST. Scan tool will perform a CCD bus test. If scan tool displays BUS
OPERATIONAL, go to next step. If scan tool displays any message except
BUS OPERATIONAL, see appropriate VEHICLE COMMUNICATIONS article.
3) Using scan tool, select READ DTCs. If any Diagnostic
Trouble Codes (fault messages) are present, go to appropriate fault
message. If no fault messages are present, identify customer
complaint. See following list for possible fault messages and customer
complaint symptoms. Problems listed are diagnosed using a scan tool.
These problems may occur separately or in various combinations. When
diagnosing a system with many apparent problems, a sequence of tests
may be required. After repairs, ensure problem(s) or failure(s) have\
been corrected.
CHIME SYSTEM
* CHIME INOPERATIVE - ENGINE TEMPERATURE CRITICAL
* CHIME INOPERATIVE - KEY IN IGNITION & LF DOOR OPEN
* CHIME INOPERATIVE AT ALL TIMES
* CHIME INOPERATIVE WITH EXTERIOR LIGHTS ON
* CHIME INOPERATIVE WITH LOW OIL PRESSURE
* CHIME INOPERATIVE WITH DRIVER DOOR OPEN
DOOR AJAR SYSTEM
* OPEN LEFT DOOR AJAR CIRCUIT
* OPEN RIGHT DOOR AJAR CIRCUIT
* SHORTED LEFT DOOR AJAR CIRCUIT
* SHORTED RIGHT DOOR AJAR CIRCUIT
INSTRUMENT CLUSTER
* ALL GAUGES INOPERATIVE
* ANY CCD CLUSTER WARNING LIGHT INOPERATIVE
* ANY HARD WIRED CLUSTER WARNING LIGHT INOPERATIVE

* ONE GAUGE NOT OPERATING PROPERLY
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)
* CMTC DISPLAY SHOWS FAILED
* CMTC SEGMENTS FAIL TO LIGHT UP
* INCORRECT READING BEYOND +/- 5
* REPAIRING "OC" IN CMTC DISPLAY
* REPAIRING "SC" IN CMTC DISPLAY
POWER DOOR LOCK SYSTEM
* DOOR LOCK SWITCH FAILURE (PDL)
* DOOR UNLOCK SWITCH FAILURE (PDL)
* AUTOMATIC (ROLLING) DOOR LOCKS INOPERATIVE
* DOORS LOCK WITH KEY IN IGNITION & LEFT DOOR OPEN
* ONE OR ALL DOORS FAILING TO LOCK FROM ONE SWITCH (ONE OR ALL
DOORS FAILING TO UNLOCK FROM ONE SWITCH)
* REMOTE KEYLESS ENTRY PROBLEM
VEHICLE THEFT/SECURITY SYSTEM
* DOOR DISARM SWITCH FAILURE
* DOOR LOCK SWITCH FAILURE
* DOOR UNLOCK SWITCH FAILURE
* EEPROM CHECKSUM FAILURE
* INTERNAL ROM TEST FAILURE
* IDENTIFYING VTSS PROBLEMS
WINDSHIELD WIPER SYSTEM
* WIPER PARK SWITCH FAILURE
* INTERMITTENT WIPERS INOPERATIVE
* NO WIPER ACTUATION AFTER WASH BUTTON PUSHED
* WIPER SPEED SENSITIVE FEATURE INOPERATIVE
CHIME SYSTEM
CHIME INOPERATIVE WITH EXTREME COOLANT TEMPERATURE
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 any module connector.
1) Using scan tool, actuate chime. If chime sounds, go to
next step. If chime does not sound, replace Central Timer Module
(CTM). CTM is located under left side of instrument panel.
2) Using scan tool, read Powertrain Control Module (PCM)
DTCs. If no engine coolant temperature related codes exist, go to next
step. If engine coolant temperature related codes exist, see
appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section.
3) Due to difficult access of coolant temperature sensor, Oil
Pressure Switch (OPS) will be used to verify CCD bus message from PCM.\
Disconnect OPS connector. OPS is located near bottom of distributor.

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 any module connector.
1) Remove driver's door panel. Disconnect driver's door ajar
switch. Using scan tool, read left front door ajar switch status. If
scan tool displays DRDOOR AJAR SW: CLOSED, go to next step. If scan
tool does not display DRDOOR AJAR SW: CLOSED, replace left front door
ajar switch.
2) Disconnect Central Timer Module (CTM) 14-pin Green
connector C1. CTM is located under left side of instrument panel.
Using an external ohmmeter, measure resistance between ground and CTM
14-pin Green connector C1 terminal No. 1 (Tan wire). If resistance is
less than 5 ohms, repair short to ground in Tan wire between CTM 14-
pin connector C1 and left front door ajar switch. If resistance is 5
ohms or more, replace CTM.
SHORTED RIGHT DOOR AJAR CIRCUIT
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 any module connector.
1) Ensure all doors are closed. Open right front door and
remove door panel. Disconnect right front door ajar switch. Using scan
tool, read right front door ajar switch status. If scan tool displays
PASSDOOR AJAR SW: CLOSED, go to next step. If scan tool does not
display PASSDOOR AJAR SW: CLOSED, replace right front door ajar
switch.
2) Disconnect Central Timer Module (CTM) 14-pin Green
connector C1. CTM is located under left side of instrument panel.
Using an external ohmmeter, measure resistance between ground and CTM
14-pin Green connector C1 terminal No. 5 (Black/Light Blue wire). If
resistance is less than 5 ohms, repair short to ground in Black/Light
Blue wire. If resistance is 5 ohms or more, replace CTM.
INSTRUMENT CLUSTER
ALL GAUGES DO NOT OPERATE
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) Turn ignition on. Using scan tool, select ELECTRO/MECH
CLUSTER. If scan tool displays BUS OPERATIONAL, go to next step. If
scan tool does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article and follow appropriate symptom diagnostics.
2) If scan tool displays NO RESPONSE, go to appropriate
VEHICLE COMMUNICATIONS article. If scan tool does not display NO
RESPONSE, go to next step.
3) Using scan tool, select SYSTEM TEST. If scan tool displays

PCM INACTIVE ON BUS, go to appropriate VEHICLE COMMUNICATIONS article.
If scan tool does not display PCM INACTIVE ON BUS, go to next step.
4) Turn ignition off. Remove instrument cluster. See
appropriate INSTRUMENT PANELS article. Turn ignition on. Using
external voltmeter, measure voltage between ground and instrument
cluster connector C1 terminal No. 6 (Yellow wire). If voltage is 10
volts or less, repair open Yellow wire. If voltage is more than 10
volts, replace instrument cluster.
ANY CCD CLUSTER LIGHT INOPERATIVE
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) Turn ignition on. Using scan tool, select ELECTRO/MECH
CLUSTER. If scan tool displays BUS OPERATIONAL, go to next step. If
scan tool does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article and follow appropriate symptom diagnostics.
2) If scan tool displays NO RESPONSE, go to appropriate
VEHICLE COMMUNICATIONS article. If scan tool does not display NO
RESPONSE, go to next step.
3) Using scan tool, select SYSTEM TEST. If scan tool displays
PCM INACTIVE ON BUS, go to appropriate VEHICLE COMMUNICATIONS article.
If scan tool does not display PCM INACTIVE ON BUS, go to next step.
4) Push and hold RESET button while cycling ignition key.
Release RESET button when CHEC appears in odometer display. Observe
inoperative light during self-test. If inoperative light did not
illuminate during self-test, go to next step. If inoperative light
illuminated during self-test, verify if light is controlled by an
input to instrument cluster. See appropriate wiring diagram in BODY
CONTROL COMPUTER - INTRODUCTION article. If light is controlled by an
input to instrument cluster, go to appropriate circuits article or
symptom test. See IDENTIFYING VEHICLE EQUIPMENT & SYSTEM PROBLEMS. If
light is not controlled by an input to instrument cluster, system is
currently functioning correctly.
5) Gain access to instrument cluster. See appropriate
INSTRUMENT PANELS article. If defective light is a LED, replace
instrument cluster. If defective light is a bulb, go to next step.
6) Remove and inspect defective bulb. If bulb is burned out,
replace bulb. If bulb is not burned out, replace instrument cluster.
ANY HARD WIRED CLUSTER WARNING LIGHT INOPERATIVE
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) Remove instrument cluster. See appropriate INSTRUMENT
PANELS article. Remove inoperative bulb. If bulb is burned out,
replace bulb. If bulb is not burned out, go to next step.
2) Inspect wiring diagram and evaluate which instrument
cluster provides; power or ground for inoperative bulb. See
appropriate wiring diagram in BODY CONTROL COMPUTER - INTRODUCTION
article. Using external ohmmeter or voltmeter, check appropriate power
or ground circuit. If circuit is okay, replace instrument cluster. If
power or ground is not available at appropriate circuit, repair open

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