engine DODGE RAM 1999 Service Repair Manual


F - B ASIC T E STIN G - R W D - G ASO LIN E

1999 D odge P ic ku p R 1500
1999 ENGINE PERFORMANCE
CHRY - Basic Diagnostic Procedures Trucks & RWD Vans
Dakota, Durango, Ram Pickup, Ram Van, Ram Wagon
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.
INTRODUCTION
The following diagnostic steps will help prevent overlooking
a simple problem. This is also where to begin diagnosis for a no-start
condition.
The first step in diagnosing any driveability problem is
verifying the customer's complaint with a test drive under the
conditions the problem reportedly occurred.
Before entering self-diagnostics, perform a careful and
complete visual inspection. Most engine control problems result from
mechanical breakdowns, poor electrical connections or
damaged/misrouted vacuum hoses. Before condemning the computerized
system, perform each test listed in this article.
NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM)\
with a minimum 10-megohm input impedance, unless stated
otherwise in test procedure.
PRELIMINARY INSPECTION & ADJUSTMENTS
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed,
stretched, cut or pinched wiring. Ensure electrical connectors fit
tightly and are not corroded. Ensure vacuum hoses are properly routed
and are not pinched or cut. Inspect air induction system for possible
vacuum leaks.
MECHANICAL INSPECTION
Compression
Ensure battery is fully charged. Warm engine to normal
operating temperature. Disconnect wire at ignition coil to prevent
engine from starting. Check engine compression with all spark plugs
removed and throttle wide open.
Check engine mechanical condition with a compression gauge,
vacuum gauge, or an engine analyzer. See engine analyzer manual for
specific instructions.
COMPRESSION SPECIFICATIONS









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Application Specification
Compression Ratio
Ram Pickup (8.0L) .......................................... 8.4:1\
All Others ................................................. 9.1:1
Normal Compression Pressure .................................... ( 1)

Minimum Compression Pressure
Dakota
2.5L ........................................................ (1)
3.9L, 5.2L & 5.9L ............................. 100 psi (690 kPa)\
Durango ........................................ 100 psi (690 kPa)\
Ram Pickup ..................................... 100 psi (690 kPa)\
Ram Van Ram Wagon .............................. 100 psi (690 kPa)\
Maximum Variation Between Cylinders ............................ ( 1)
( 1) - Information is not available from manufacturer.









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FUEL SYSTEM
FUEL PRESSURE RELEASE
WARNING: Fuel system is under high pressure. ALWAYS release fuel
pressure before attempting to open system for testing or
component replacement. DO NOT allow fuel to flow onto engine
or electrical parts while testing fuel system components.
Vehicles With Fuel Rail Test Port
1) Loosen fuel tank filler cap. Ensure ignition is off.
Remove protective cap from fuel rail test port.
2) Place one end of Fuel Pressure Release Hose (C-4799-1)
into an approved fuel container. Attach remaining end of hose to fuel
rail test port. Use care, as fuel system may be under pressure. Fuel
pressure will be released from fuel system. Remove hose, reinstall
protective cap, and fuel tank filler cap.
3) Wait 5 seconds. Use care when disconnecting fuel lines, as
some fuel pressure may still exist in fuel lines.
NOTE: One or more DTCs may set when fuel pump relay is removed.
Clear DTCs from PCM after fuel pressure release procedure. To
clear DTCs from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC
SYSTEM in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Vehicles Without Fuel Rail Test Port
1) Remove gas cap. Using a non-metallic tool, open flapper
valve in filler neck to relieve pressure. Remove fuel pump relay from
Power Distribution Center (PDC). Relays are identified on label under
PDC cover. Start and run engine until it stalls. Attempt to start
engine. Continue restarting engine until it will no longer run. Turn
ignition off.
CAUTION: DO NOT supply power to fuel injector for more than 4 seconds,
or fuel injector may be damaged.
2) Disconnect any fuel injector connector. Connect a jumper
wire between either fuel injector terminal and positive battery
terminal. Connect another jumper wire to other fuel injector terminal.
Momentarily touch other end of jumper wire to negative battery
terminal.
3) Place a shop towel under fuel line quick-connector at fuel
rail. Use care when disconnecting fuel lines, as some fuel pressure
may still exist in fuel lines. Disconnect fuel line quick-connector.
Reinstall fuel pump relay in PDC. Clear DTCs from PCM. To clear DTCs
from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC SYSTEM in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
FUEL PRESSURE TEST

NOTE: For additional information on fuel pressure and fuel pump
testing procedures, see appropriate NO TROUBLE CODE (NTC)
TEST and NO START (NS) TEST in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Vehicles With Fuel Rail Test Port
1) Disconnect negative battery cable. Release fuel pressure.
See FUEL PRESSURE RELEASE. Install fuel pressure gauge with hose on
fuel pressure test port.
2) Start engine and allow to idle. Fuel pressure should be
44-54 psi (3.1-3.8 kg/cm
). If no fuel pressure exists and engine will
not start, fuel pump relay and control circuit may be defective. See
FUEL PUMP RELAY.
3) If fuel pressure exceeds specification, fuel pump is okay,
but fuel pressure regulator is defective. Replace fuel pressure
regulator. Fuel pressure regulator is incorporated with the fuel
filter. Fuel filter/fuel pressure regulator is located on top of fuel
tank, in fuel pump module. See REMOVAL, OVERHAUL & INSTALLATION -
TRUCKS & RWD VANS - GASOLINE article.
Vehicles Without Fuel Rail Test Port
1) Disconnect negative battery cable. Release fuel pressure.
See FUEL PRESSURE RELEASE. Fuel pressure gauge is installed between
fuel supply line and fuel line fitting on fuel rail.
2) To disconnect fuel supply line from fuel rail, ensure area
around fuel supply line and fuel rail are clean. Note direction of
latch clip installation. Latch clip is located on top of fuel supply
line at fuel rail. See Fig. 1. Using 2 screwdrivers, pry latch clip
upward, and remove from fuel rail.
3) Pull fuel supply line from fuel rail. Install Adapter
(6923) into fuel rail. Ensure adapter is fully seated in fuel rail.
Install latch clip into fuel rail, with latch clip fingers pointing
downward. If latch clip will not fully seat so latch clip fingers
extend downward below fitting on fuel rail, adapter may not be fully
seated in fuel rail.
4) Connect fuel supply line to adapter. Ensure fuel supply
line fully seats in adapter. Remove protective cap from test port, and
install Fuel Pressure Gauge/Hose (5069) at test port.
5) Start engine and allow to idle. Fuel pressure should be
44-54 psi (3.1-3.8 kg/cm
). If no fuel pressure exists and engine will
not start, fuel pump relay and control circuit may be defective. See
FUEL PUMP RELAY.
6) If fuel pressure exceeds specification, fuel pump is okay,
but fuel pressure regulator is defective. Replace fuel pressure
regulator. Fuel pressure regulator is incorporated with the fuel
filter. Fuel filter/fuel pressure regulator is located on top of fuel
tank, in fuel pump module. See REMOVAL, OVERHAUL & INSTALLATION -
TRUCKS & RWD VANS - GASOLINE article.
7) On all models, release fuel pressure. See FUEL PRESSURE
RELEASE. Remove latch clip. Remove test equipment. Before reinstalling
fuel supply line, ensure fuel supply line fitting and fitting on fuel
rail are clean.
8) Lubricate fuel supply line fitting and fitting on fuel
rail with engine oil. Install fuel supply line on fuel rail.
9) Install latch clip into fuel rail, with latch clip fingers
pointing downward. Ensure latch clip is fully seated. Latch clip
fingers should extend downward below fitting on fuel rail when fully
seated.
10) Pull on fuel supply line to ensure fuel supply line is
fully locked on fuel rail. Reinstall negative battery cable. Start
engine and check for fuel leaks.

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.

Connect a jumper wire between OPS connector terminals. Start engine
and allow to idle for 20 seconds. Increase engine speed to 1600 RPM.
If chime sounds, system is currently functioning properly. If chime
does not sound, go to next step.
4) Remove instrument cluster. See appropriate INSTRUMENT
PANELS article. Disconnect Instrument cluster 10-pin Gray connector
"B". Connect a jumper wire between ground and Dark Blue/Red wire of
instrument cluster 10-pin Gray connector terminal No. 7. Turn ignition
on. If chime sounds, replace instrument cluster. If chime does not
sound, repair open Dark Blue/Red wire.
CHIME INOPERATIVE - KEY IN IGNITION & LF DOOR OPEN
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) Turn ignition off. Open driver's door. If chime does not
sound, go to next step. If chime sounds, system is currently
functioning correctly.
2) Using scan tool, read driver's door ajar switch status. If
scan tool displays LFDOOR AJAR SWITCH: CLOSED, go to next step. If
scan tool does not display LFDOOR AJAR SWITCH: CLOSED, go to OPEN LEFT
DOOR AJAR CIRCUIT.
3) Using scan tool, read key-in ignition chime state. If scan
tool does not display KEY-IN IGNITION CHIME STATE: ON, go to next
step. If scan tool displays KEY-IN IGNITION CHIME STATE: ON, replace
Central Timer Module (CTM). CTM is located under left side of
instrument panel.
4) Disconnect key-in ignition switch connector. See Fig. 1.
Connect jumper wire between key-in ignition switch connector Light
Blue wire and ground. Using scan tool, read key-in ignition chime
state. If scan tool does not display KEY-IN IGNITION CHIME STATE: ON,
go to next step. If scan tool displays KEY-IN IGNITION CHIME STATE:
ON, replace ignition switch. See appropriate STEERING COLUMN SWITCHES
article.
Fig. 1: Identifying Steering Column Harness Connector Locations
Courtesy of Chrysler Corp.
5) Access CTM 14-pin Green connector C1. Remove connector
cover. Do not disconnect connector. Connect a backprobe jumper wire

disconnecting any module connector.
1) Disconnect Oil Pressure Switch (OPS). OPS is located near\
bottom of distributor. Connect a jumper wire between OPS connector
terminals. Start engine and allow to idle for 20 seconds. Increase
engine speed to 1600 RPM. If chime sounds, go to next step. If chime
does not sound, go to step 3).
2) Turn ignition on. Using scan tool, actuate chime. If chime
does not sound, replace Central Timer Module (CTM). CTM is located
under left side of instrument panel. If chime sounds, system is
currently functioning properly.
3) Using scan tool, access CLUSTER MONITOR. With engine
running, read CCD oil pressure. If scan tool reading does not match
instrument cluster reading, replace instrument cluster. If scan tool
reading matches instrument cluster reading, go to next step.
4) Remove jumper wire. Connect a jumper wire between ground
and OPS connector Gray wire. Start engine and allow to idle for 20
seconds. Increase engine speed to 1600 RPM. If chime sounds, repair
open ground circuit between OPS connector and ground. If chime does
not sound, go to next step.
5) Turn ignition on. Using scan tool, actuate chime. If chime
does not sound, replace Central Timer Module (CTM). CTM is located
under left side of instrument panel. If chime sounds, go to next step.
6) Remove instrument cluster. See appropriate INSTRUMENT
PANELS article. Disconnect CTM 14-pin Green connector C1. Using an
external ohmmeter, measure resistance of Dark Blue/Red wire between
CTM 14-pin Green connector C1 terminal No. 2 and instrument cluster
10-pin connector C2 terminal No. 7. If resistance is less than 5 ohms,
replace CTM. If resistance is 5 ohms or more, repair open Dark
Blue/Red wire.
CHIME SOUNDS WITH DRIVER DOOR OPEN
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 interior and exterior lights are off. Remove
ignition key and open driver's door. If chime does not sound, system
is currently functioning correctly. If chime sounds, go to next step.
2) Using scan tool, read key-in ignition chime state. If scan
tool displays KEY-IN IGNITION CHIME STATE: "ON/OFF", go to next step.
If scan tool does not display KEY-IN IGNITION CHIME STATE: "ON/OFF",
replace Central Timer Module (CTM). CTM is located under left side of
instrument panel.
3) Disconnect key-in ignition switch connector. See Fig. 1.
Using scan tool, read key-in ignition chime state. If scan tool
displays KEY-IN IGNITION CHIME STATE: ON, go to next step. If scan
tool does not display KEY-IN IGNITION CHIME STATE: ON, replace
ignition switch. See appropriate STEERING COLUMN SWITCHES article.
4) Turn ignition off. Disconnect Central Timer Module (CTM).\
CTM is located under left side of instrument panel. Remove ignition
key. Ensure all lights and accessories are off. Close all doors. Using
external ohmmeter, measure resistance between ground and terminal No.
9 (Light Blue wire) on CTM Green connector "A". If resistance is less
than 10 ohms, repair Light Blue wire between CTM and ignition switch
for short to ground. If resistance is 10 ohms or more, replace CTM.
DOOR AJAR SYSTEM

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

VERIFICATION TEST VER-1A after each repair.
CAUTION: Always turn ignition switch to OFF position prior to
disconnecting or connecting any module connector.
1) Clear trouble codes as needed. See BODY CONTROL COMPUTER -
INTRODUCTION article. Using scan tool, read I/O's door unlock switch
status. If scan tool displays RELEASED, system is currently
functioning properly. If scan tool does not display RELEASED, go to
next step.
2) Disconnect left door lock switch connector. If scan tool
displays RELEASED, replace left door lock switch. If scan tool does
not display RELEASED, go to next step.
3) Disconnect right door lock switch connector. If scan tool
displays RELEASED, replace right door lock switch. If scan tool does
not display RELEASED, go to next step.
4) Locate Central Timer Module (CTM). CTM is located under
left side of instrument panel. Disconnect CTM 18-pin connector C2.
Using an external voltmeter, measure voltage between ground and CTM
18-pin connector C2 terminal No. 4 (Orange/Dark Green wire). If
voltage is more than 1.5 volts, repair short to voltage in Orange/Dark
Green wire between CTM and door lock switch. If voltage is 1.5 volts
or less, replace CTM.
IDENTIFYING VTSS PROBLEMS
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) Using scan tool, select BODY SYSTEM then VTSS and read
Central Timer Module (CTM) DTCs. If any VTSS DTCs are displayed,
perform appropriate procedure. See VTSS DTC table. If no VTSS DTCs are
displayed, go to next step.
VTSS DTC









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DTC Message Perform
DOOR DISARM SWITCH FAILURE .............. DOOR DISARM SWITCH FAILURE
DOOR LOCK SWITCH FAILURE .................. DOOR LOCK SWITCH FAILURE
DOOR UNLOCK SWITCH FAILURE .............. DOOR UNLOCK SWITCH FAILURE
EEPROM CHECKSUM FAILURE ................................ Replace CTM
INTERNAL ROM TEST FAILURE .............................. Replace CTM









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2) Select VTSS then MONITORS. If scan tool displays, OK TO
RUN, NOT OK TO ARM, PCM has not recorded more than 20 starts. Start
engine 20 times and retest. If message does not change to OK TO ARM,
replace PCM. If scan tool displays NO RESPONSE TO PCM, see appropriate
VEHICLE COMMUNICATIONS article. If scan tool does not display OK TO
RUN, NOT OK TO ARM or NO RESPONSE TO PCM, go to next step.
3) Using scan tool, actuate horn, headlights and VTSS light
to flash. If horn does not sound, go to next step. If headlights do
not flash, go to step 6). If VTSS light does not flash, go to step 9).\
If all function properly, go to step 12).
4) Press horn button. If horn does not sound, go to
appropriate STEERING COLUMN SWITCHES article. If horn sounds, go to
next step.
5) Locate Central Timer Module (CTM). CTM is located behind