stop start DODGE RAM 1999 Service Repair Manual

knob pointer) is flush with base of A/C-heater control panel.
5) Rotate temperature control knob to its full clockwise
stop. Release knob. Knob pointer should be aimed at end of Red stripe.
If knob is pointed at end of Red stripe, go to next step. If knob is
not pointed at end of Red stripe, go back to step 2) and repeat
adjustment procedure.
6) Rotate temperature control knob to its full
counterclockwise stop. Release knob. If knob springs back, self-
adjuster clip securing temperature control cable to blend-air door
lever is improperly installed. See TEMPERATURE CONTROL CABLE R & I. If
knob does not spring back, temperature control cable adjustment is
complete.
TESTING
* PLEASE READ THIS FIRST *
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY
article.
A/C-HEATER CONTROL PANEL TEST
1) Connect a vacuum gauge in line with Black A/C-heater
vacuum supply hose, located at tee near power brake booster (Dakota)
or in engine compartment (Durango and Ram Pickup). Position gauge so
it can be viewed from passenger compartment.
2) Start engine. While observing gauge, rotate mode control
knob to each mode position (one position at a time). Pause after each
selection. Test gauge should drop, then return to 8 in. Hg shortly
after each selection is made. If gauge reading is as specified, go to
next step. If gauge reading is not as specified, check for vacuum leak
in vacuum lines or A/C-heater control panel.
3) Move temperature control knob quickly to full hot and full
cold positions. A distinct sound of blend-air door hitting its stops
should be heard. No spring-back of knob should exist.
4) If temperature control knob operates as specified,
temperature control system is okay. On Dakota and Durango, if
temperature control knob does not operate as specified, check
condition, routing, installation, and adjustment of temperature
control cable. See TEMPERATURE CONTROL CABLE ADJUSTMENT . Also check
blend air door for proper installation, obstructions, or faulty seals.
A/C SYSTEM PERFORMANCE
1) Park vehicle out of direct sunlight. Ensure ambient
temperature is at least 70F (21C). Connect tachometer and manifold
gauge set to vehicle. Turn A/C on. Turn mode control to panel and
recirculated air positions, temperature control lever to maximum
cooling, and blower to high.
2) Start engine and allow it to run at 1000 RPM, with A/C
compressor clutch engaged. Engine should be at operating temperature
with doors, windows, and hood closed. Insert thermometer into left
center air outlet.
3) Run engine and operate system for 5 minutes. The A/C
compressor clutch may cycle, depending on temperature. If A/C
compressor clutch cycles, stop engine and disconnect negative battery
cable. Remove clutch cycling pressure switch connector. Place a jumper
wire across terminals of clutch cycling pressure switch harness
connector.
4) Connect negative battery cable. Turn A/C on. Start and

1) Manufacturer recommends flushing contaminated system using
one gallon of Ford A/C System Flushing Solvent (F4AZ-19579-A), a
Filter (FL-1A), an A/C Flusher Fitting Kit (014-00992). DO NOT reuse\
flushing solvent and filter, they are intended to be used on one
vehicle only.
2) Discharge A/C system, using approved refrigerant
recovery/recycling equipment. Flush specified A/C components using A/C
System Flusher (014-00991), according to manufacturer's operating
instructions.
3) If an A/C system flusher is not available to clean A/C
system, an in-line filter kit can be used. Filter kit is installed
before replacement compressor, accumulator/receiver-drier, muffler,
and thermal expansion valve/fixed orifice tube have been installed.
4) Filter kits are used with either a rubber lined suction
hose or with a nylon lined suction hose located between compressor and
evaporator. Rubber lined hose has a wall thickness of 1/4" and nylon
lined hose has a wall thickness of 1/8". See Fig. 22.
5) The filter kit for either type hose has 2 filters. A
temporary pancake filter and a permanent in-line suction filter.
Pancake filter is temporarily installed between condenser and
condenser-to-evaporator line. See Fig. 23. Permanent filter is
installed in suction line between accumulator and compressor.
6) Install replacement components (compressor, accumulator
and fixed orifice) with correct amount of refrigerant oil. See
COMPRESSOR REFRIGERANT OIL CHECKING article.
7) Cut suction hose between compressor and accumulator
(closer to compressor). Remove a length of suction hose to accommodate\
suction filter. Measure side wall of suction hose and install
appropriate filter with "O" rings and filter clamps. If side wall is
1/4", use in-line filter labeled USE WITH RUBBER INNER LINED HOSE. If
side wall is 1/8", use in-line filter labeled USE WITH NYLON INNER
LINED HOSE. Ensure arrow on filter is pointing in direction of
refrigerant flow. Tighten hose clamps to 54 INCH lbs. (6 N.m). See
Fig. 22 .
8) Install pancake filter in liquid line between condenser
and condenser-to-evaporator line. Ensure filter inlet (label) is
toward condenser. Evacuate, charge, and leak test A/C system. See
EVACUATING A/C SYSTEM, CHARGING A/C SYSTEM and LEAK TESTING. Check
filters and hoses for clearance from other engine components. Use tie
straps if necessary.
9) Place an external cooling fan in front of radiator. Select
MAX A/C operation and set blower motor speed to maximum. Start engine
and allow to idle. Ensure A/C is operating properly. Slowly increase
engine speed to 800 RPM, then 1000 RPM, and then to 1200 RPM. With
engine speed set to 1200 RPM, operate engine for one hour with A/C
system operating.
10) Stop engine. Discharge A/C system, using approved
refrigerant recovery/recycling equipment. Remove pancake filter, hoses
and fittings. Discard pancake filter. Reconnect liquid line, evacuate,
charge, and leak test A/C system. Ensure A/C system is operating
properly.

vacuum reading of 26 in. Hg or more. Close all valves and turn vacuum
pump off. Observe vacuum gauge, go to next step.
2) If A/C system maintains specified vacuum for 5 minutes,
open low-side and high-side valves, restart vacuum pump and operate
for an additional 10 minutes. Close all valves. Turn vacuum pump off
and disconnect pump.
3) If A/C system cannot get to or maintain specified vacuum,
check for a defective vacuum pump or leak in A/C system or gauge set.
See LEAK TESTING. Repair or replace components as necessary.
CHARGING A/C SYSTEM
* PLEASE READ THIS FIRST *
CAUTION: During charging of A/C system, refrigerant container must be
in an upright position. If refrigerant container is
upside down, compressor may be damaged by liquid refrigerant
drawn into A/C system.
CHRYSLER CORP.
Avenger 2.0L & Sebring Coupe 2.0L
1) Ensure A/C system has no leaks and has been evacuated. See
EVACUATING A/C SYSTEM and LEAK TESTING. Locate sight glass on
receiver-drier and ensure it is clean. Close low-pressure adapter
valve and remove from manifold gauge set.
2) Connect low-pressure adapter valve to refrigerant
container and open container valve. Ensure Blue charging hose is
properly connected to vehicle low-pressure service valve. Open adapter
valve.
3) If refrigerant is not drawn in, fully close adapter valve
and check for hose connection leaks. If leak is detected, retighten
connections and repeat A/C system evacuation. See EVACUATING A/C
SYSTEM.
4) If refrigerant is drawn in, start engine. Turn A/C on and
set temperature control to maximum cold and blower motor to low speed.
Operate engine at 1500 RPM. As refrigerant is drawn into system, foam
or bubbles will appear in sight glass.
5) System charge will be close to full when sight glass is
clear, compressor clutch is engaged, and compressor suction and
discharge line temperatures are similar. System charge will be
complete when sight glass is clear, compressor clutch is engaged,
compressor discharge line is warm and suction line is cool.
6) When proper amount of refrigerant has been added, stop
engine. Close refrigerant container and adapter valve, and disconnect
gauge set.
Breeze, Cirrus, Concorde, Intrepid, LHS, Stratus & 300M (Scan
Tool Method)
1) Attach Diagnostic Readout Box (DRB) to Data Link Connecto\
r
(DLC). Set DRB (scan tool) to PARTIAL CHARGE TEST. Attach clamp-on
Thermocouple (80PK-1A) to liquid line, as close to condenser outlet as\
possible.
2) Set parking brake, and place transaxle in Park position.
Start engine and allow to idle. Set A/C controls to outside air, panel
mode, full cool, and high blower speed. Turn A/C on, and open vehicle
windows. Operate A/C system for a few minutes to allow system to
stabilize.
3) Place cardboard over front grille area, to block airflow
through part of condenser, to set A/C system pressure to 260 psi (18.3
kg/cm
). This will stop cooling fans from alternating speeds and
maintain constant pressure.

4) Scan tool will automatically calculate system charge.
Depending on system charge condition, corrections are made 2 ounces at
a time. Each time a correction is made, recheck readings to ensure
proper charge. For system refrigerant capacity, see REFRIGERANT OIL &
REFRIGERANT SPECIFICATIONS article.
Breeze, Cirrus, Concorde, Intrepid, LHS, Stratus & 300M
(Manifold Gauge Set Method)
1) Attach clamp-on Thermocouple (80PK-1A) to liquid line, as\
close to condenser outlet as possible. Attach manifold gauge set to
vehicle.
2) Set parking brake, and place transaxle in Park position.
Start engine and allow to idle. Set A/C controls to outside air, panel
mode, full cool, and high blower speed. Turn A/C on, and open windows.
Operate system for a few minutes to allow system to stabilize.
3) Place cardboard over front grille area, to block airflow
through part of condenser, to set A/C pressure to 260 psi (18.3
kg/cm
). This will stop cooling fans from alternating speeds and
maintain constant pressure.
4) Record temperature reading at liquid line and discharge
pressure reading on gauges. Compare readings with values in
REFRIGERANT CHARGE LEVEL table.
5) Depending on system charge condition, corrections are made
2 ounces at a time. Each time a correction is made, recheck readings
to ensure proper charge. For system refrigerant capacity, see
REFRIGERANT OIL & REFRIGERANT SPECIFICATIONS article.
REFRIGERANT CHARGE LEVEL









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Liquid Line Temp. ( 1) Discharge PressureF (C) psi (kg/cm)
40 (4.4) ........................................... 53-75 (3.7-5.3\
)
60 (15.6) ......................................... 81-104 (5.7-7.3\
)
80 (26.7) ....................................... 111-142 (7.8-10.0\
)
100 (37.8) ..................................... 156-194 (11.0-13.6\
)
120 (48.9) ..................................... 208-259 (14.6-18.2\
)
140 (60.0) ..................................... 272-331 (19.1-23.3\
)
160 (71.1) ..................................... 353-420 (24.8-29.5\
)
180 (82.2) ..................................... 447-516 (31.4-36.3\
)
( 1) - When pressure is lower than specified, system is undercharged.
When pressure is higher than specified, system is overcharged.









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All Other Models
Ensure A/C system has been checked for leaks and evacuated.
See EVACUATING A/C SYSTEM and LEAK TESTING. Charge A/C system to
specifications. For system refrigerant capacity, see REFRIGERANT OIL &
REFRIGERANT SPECIFICATIONS article.
FORD MOTOR CO.
1) If using approved Recovery/Recycling/Charging Center (023-\
00105 or 023-00150), connect to high-side and low-side service valves.
See SERVICE VALVE LOCATIONS under SYSTEM SERVICE VALVES. Operate
charging center according to manufacturer's instructions. Charge
system with specified amount of refrigerant and refrigerant oil. See
REFRIGERANT OIL & REFRIGERANT SPECIFICATIONS article. Check amount of
refrigerant oil in system before adding oil. See COMPRESSOR
REFRIGERANT OIL CHECKING article.
2) If using manifold gauge set, connect to high-side and low-
side service valves. See SERVICE VALVE LOCATIONS under SYSTEM SERVICE

CAUTION: When removing a deployed air bag, wear eye protection, rubber
gloves and a long-sleeve shirt. Powder residue from air bag
deployment may irritate skin and eyes.
CAUTION: Before removing steering wheel, position front wheels in
straight-ahead position and lock steering column by removing
ignition key. Failure to do so could damage clockspring or
cause clockspring to be off-centered. DO NOT hammer on
steering wheel during removal, or collapsible column could be
damaged.
Removal
1) Before proceeding, see SERVICE PRECAUTIONS. Disable air
bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM . Air bag module
is mounted on face of steering wheel. Ensure wheels are pointed
straight-ahead and steering wheel is locked.
2) Remove air bag module-to-steering wheel screws from back
side of steering wheel. Lift air bag module and disconnect electrical
connectors from rear of module.
Installation
Connect air bag, cruise control and horn harness connectors
to rear of air bag module. Secure module to steering wheel. Tighten
air bag module-to-steering wheel screws to specification. See
TORQUE SPECIFICATIONS . DO NOT connect negative battery cable at this
time. Go to SYSTEM OPERATION CHECK .
PASSENGER-SIDE AIR BAG MODULE
Removal
1) Before proceeding, see SERVICE PRECAUTIONS. Disable air
bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM .
2) Open glove box. Holding glove box door, push center of
glove box bin towards front of vehicle. Flex glove box bin far enough
so glove box stops will clear sides of instrument panel opening. Roll
glove box down until stop bumpers are beyond sides of instrument panel
opening. Release bin. Lift bottom of glove box upward to disengage
hinge hooks form hinge pins.
3) Remove 3 screws securing instrument panel glove box
opening upper trim strip to instrument panel glove box opening upper
reinforcement, then remove trim strip. Remove 4 screws that secure 2
plastic support brackets of passenger-side air bag door panel outlet
housing to glove box opening upper reinforcement.
4) Reach through and above glove box opening to access and
disconnect air bag module harness connector. Remove 2 screws securing
passenger-side air bag module front bracket to instrument panel
structural support. Remove 3 screws securing passenger-side air bag
module rear bracket to glove box opening upper reinforcement.
5) Using trim stick, gently pry passenger-side air bag door
(starting at lower left edge) away from instrument panel top cover.
Remove air bag module, air bag door and panel outlet housing and
barrel assembly from instrument panel as a unit.
Installation
To install, reverse removal procedure. Ensure air bag door is
securely attached to instrument panel. Ensure air bag harness
connector latches fully engaged. DO NOT connect negative battery cable
at this time. Go to SYSTEM OPERATION CHECK .
CLOCKSPRING
CAUTION: Failure to position wheels in the straight-ahead position
with steering wheel locked when removing steering wheel could

NOTE: All active codes must be resolved before diagnosing store
codes.
1) Raise and support vehicle. Start engine and let idle with
transmission in PARK position. Wiggle wiring harness and connectors of
air bag system and rotate steering wheel from stop to stop.
2) Visually inspect related wire harness connectors. Look for
broken, bent, pushed out, spread, corroded or contaminated terminals.
Also, look for chafed, pierced, pinched or partially broken wires.
3) Check for trouble codes as you work through system. If
stored trouble code becomes active, perform appropriate diagnostic
test. If stored code is reproducible, repair or replace wiring
harness, harness connector or terminals or replace component as
necessary.
CLUSTER MESSAGE MISMATCH
NOTE: Perform AIR BAG VERIFICATION TEST after
all repairs. Each time a connector is disconnected, inspect
it to ensure it is in good condition. Always focus on circuit
being tested. Dirt, water and corrosion, are most common
problems in connectors. Due to manufacturer changes in wire
colors, use terminal identification whenever possible.
1) If AIR BAG warning light is on, go to next step. If AIR
BAG warning light is not on, go to step 5).
2) Using DRB, select PASSIVE RESTRAINTS, AIRBAG and MONITOR
DISPLAY. Read WARNING LAMP STATUS. If DRB does not display MIC LAMP
STATUS ON, replace instrument cluster. If DRB displays MIC LAMP STATUS
ON, go to next step.
3) If DRB displays ACM LAMP REQUEST: ON, go to next step. If
DRB does not display ACM LAMP REQUEST: ON, replace instrument cluster.
4) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
NOTE: If AIR BAG warning light is defective, instrument cluster
will flash seat belt light for 30 seconds starting 10 seconds
after bulb check stops.
5) Using DRB, read air bag control module active codes
(messages). If CLUSTER MISMATCH is only active message, go to next
step. If other messages are present, go to appropriate diagnostic test
to continue diagnosis.
6) If seat belt warning light flashes for 30 seconds after
bulb check is complete, replace instrument cluster. If seat belt
warning light does not flashes for 30 seconds after bulb check is
complete, go to next step.
7) Using DRB, select PASSIVE RESTRAINTS, AIRBAG and MONITOR
DISPLAY. Read WARNING LAMP STATUS. If DRB displays ACM LAMP REQUEST:
OFF, go to next step. If DRB does not display ACM LAMP REQUEST: OFF,
replace instrument cluster.
8) If DRB displays MIC LAMP REQUEST: OFF, go to next step. If
DRB does not display MIC LAMP REQUEST: OFF, replace instrument
cluster.
9) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
DRIVER SQUIB CIRCUIT OPEN
NOTE: Perform AIR BAG VERIFICATION TEST after
all repairs. Each time a connector is disconnected, inspect

5) If PCM has not been replaced, and TEST VER-2A is being
performed after an A/C relay control circuit DTC test, ensure A/C is
on and go to next step.
6) Road test vehicle for at least 5 minutes. Road test
vehicle at a speed of at least 40 MPH at some point during road test.
Stop vehicle. Turn engine off for at least 10 seconds. Start engine
and continue road test. Ensure transmission shifts through all gears.
After road test, turn engine off and go to next step.
7) Using scan tool, read DTCs. If any DTC returns, perform
appropriate test(s). If no DTCs return, test is complete. Go to next
step.
8) Turn ignition on, with engine off. Using scan tool, erase
DTCs. Turn ignition off. Disconnect scan tool. Test is complete.
TEST VER-2A (DIESEL)
NOTE: If Accelerator Pedal Position Sensor (APPS), battery, Engine
Control Module (ECM) or Powertrain Control Module (PCM) has\
been disconnected or replaced, APPS must be reprogrammed and
correct vehicle mileage and Vehicle Identification Number
(VIN) must be programmed into PCM to prevent Diagnostic
Trouble Codes (DTCs) from being set in Anti-Lock Brake System\
(ABS) module and Supplemental Restraint System (SRS) module\
.
To program PCM and clear DTCs from ABS and SRS modules,
proceed to appropriate procedure listed below. On models
equipped with a Smart Key Immobilizer Module (SKIM), if
replacing Powertrain Control Module (PCM), secret key data
must also be updated to enable engine starting. To update
secret key data, proceed to appropriate procedure listed
below.
CAUTION: DO NOT attempt to adjust screws or disassemble APPS. Settings
are preset at factory and are not intended to by changed.
Procedure For Programming APPS
Reassemble all components. Turn ignition switch to ON or RUN
position without starting engine. Slowly press accelerator pedal to
floor once and slowly release. This procedure programs APPS
calibration in ECM. Go to step 1)).
Procedure For Programming PCM & Clearing DTCs From ABS & SRS
Modules
Connect scan tool to Data Link Connector (DLC). Using scan
tool, enter correct VIN and mileage into PCM. Using scan tool
manufacturer's instructions, clear DTCs from ABS and SRS modules. Go
to step 1)).
Procedure For Updating Secret Key Data
Connect scan tool to Data Link Connector (DLC). Go to ENGINE
and then MISC menus on scan tool. Place SKIM in SECURED ACCESS MODE by
using appropriate Personal Identification Number (PIN) for this
vehicle. PIN may be obtained from owner, vehicle's invoice, or from
manufacturer. Select UPDATE THE SECRET KEY DATA. Data will be
transferred from Smart Key Immobilizer Module (SKIM) to PCM. Go to
step 1)).
1) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after a No Trouble Code (NTC) test, inspect vehicle to\
ensure all engine components are connected. Reassemble and reconnect
components as necessary. Check if initial symptom still exists. If
initial symptom exists, check for Technical Service Bulletins (TSBs)
that apply to vehicle and see TEST NTC-1A: NO TROUBLE CODE TEST MENU
in ENGINE PERFORMANCE, or appropriate TROUBLE SHOOTING - NO CODES

article in ENGINE PERFORMANCE for diagnosis by symptom. If initial
symptom no longer exists, test is complete. Go to step 6).
2) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after a DTC test, inspect vehicle to ensure all engine
components are connected. Reassemble and reconnect components as
necessary. Using scan tool, erase DTCs, reset all memory values and go
to step 4).
3) If PCM has not been replaced, and TEST VER-2A (DIESEL) is\
being performed after an A/C relay control circuit DTC test, ensure
A/C is on and go to next step.
4) Road test vehicle for at least 5 minutes. Road test
vehicle at a speed of at least 40 MPH at some point during road test.
Stop vehicle. Turn engine off for at least 10 seconds. Start engine
and continue road test. Ensure transmission shifts through all gears.
After road test, turn engine off and go to next step.
5) Using scan tool, read DTCs. If any DTC returns, perform
appropriate test(s). If no DTCs return, test is complete. Go to next
step.
6) Turn ignition on, with engine off. Using scan tool, erase
DTCs. Turn ignition off. Disconnect scan tool. Test is complete.
TEST VER-5A (EXCEPT DIESEL)
NOTE: If Powertrain Control Module (PCM) is replaced, correct
vehicle mileage and Vehicle Identification Number (VIN) must
be programmed into PCM to prevent Diagnostic Trouble Codes
(DTCs) from being set in Anti-Lock Brake System (ABS) modul\
e
and Supplemental Restraint System (SRS) module. To program
PCM and clear DTCs from ABS and SRS modules, proceed to
appropriate procedure listed below. On models equipped with a
Smart Key Immobilizer Module (SKIM), if replacing Powertrain
Control Module (PCM), secret key data must also be updated to\
enable engine starting. To update secret key data, proceed to
appropriate procedure listed below.
Procedure For Programming PCM & Clearing DTCs From ABS & SRS
Modules
Connect scan tool to Data Link Connector (DLC). Using scan
tool, enter correct VIN and mileage into PCM. Using scan tool
manufacturer's instructions, clear DTCs from ABS and SRS modules. Go
to step 1)).
Procedure For Updating Secret Key Data
Connect scan tool to Data Link Connector (DLC). Go to ENGINE
and then MISC menus on scan tool. Place SKIM in SECURED ACCESS MODE by
using appropriate Personal Identification Number (PIN) for this
vehicle. PIN may be obtained from owner, vehicle's invoice, or from
manufacturer. Select UPDATE THE SECRET KEY DATA. Data will be
transferred from Smart Key Immobilizer Module (SKIM) to PCM. Go to
step 1)).
1) Inspect vehicle to ensure all engine components are
connected. Reassemble and reconnect components as necessary. If any
DTCs have not been diagnosed, return to appropriate test(s). If all
DTCs have been diagnosed and repaired, go to next step.
2) Connect scan tool to Data Link Connector (DLC) if not
previously done. Ensure fuel tank is at least 1/4 full. Ensure A/C is
off. Go to next step.
3) Proper way to ensure DTC is repaired is to allow
Powertrain Control Module (PCM) to run monitor. Monitor operation may
be observed on scan tool. All specified enabling conditions for
specified DTC must be met before PCM will operate monitor. Go to next
step.

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

1) Start engine, and check booster vacuum hose connections. A
hissing noise indicates a vacuum leak. Repair any vacuum leaks before
proceeding. Stop engine, and shift transmission into Neutral. Pump
brake pedal until all vacuum reserve in booster is depleted.
2) Hold brake pedal under light pressure. If pedal does not
hold firm and falls away, master cylinder may be faulty. Bleed system
using appropriate method, and repeat step 1). See BLEEDING PROCEDURES
under BLEEDING BRAKE SYSTEM.
3) If pedal still does not hold firm, master cylinder is
faulty. If pedal holds firm, start engine and observe pedal height. If
pedal height change is not apparent, power booster or vacuum check
valve is faulty. Install good check valve, and repeat steps 1) and 2).\
If pedal falls away slightly under light pressure and then holds firm,
go to next step .
4) Start engine. Release brake pedal. Increase engine speed
to 1500 RPM. Close throttle and immediately turn off ignition. Wait at
least 90 seconds, and try brake action again. Booster should provide 2
or more vacuum assisted pedal applications. If vacuum assist is not
provided, perform booster and check valve vacuum tests.
POWER BRAKE BOOSTER VACUUM TEST
Connect vacuum gauge to booster check valve using "T"
fitting. Start engine, and run at idle speed for one minute. Clamp
hose shut between vacuum source and check valve. Stop engine, and
observe vacuum gauge. If vacuum drops more than one in. Hg within 15
seconds, booster diaphragm or check valve is faulty.
POWER BRAKE BOOSTER CHECK VALVE TEST
Disconnect vacuum hose from check valve. Remove check valve
and valve seal from booster. Use a hand-operated vacuum pump for
testing. Apply 15-20 in. Hg at large end of check valve. Vacuum should
hold steady. If gauge on pump indicates vacuum loss, check valve is
faulty and should be replaced.
COMBINATION VALVE METERING VALVE TEST
Metering valve operation can be checked visually with aid of
an assistant. While an assistant applies and releases brake pedal,
observe metering valve stem. If valve is operating correctly, stem
will extend slightly when brakes are applied, and contract when brakes
are released. If valve is faulty, replace combination valve assembly.
COMBINATION VALVE PRESSURE DIFFERENTIAL SWITCH TEST
1) Using an assistant, apply brake pedal. Observe brake
warning light. Raise and support vehicle, and connect a bleed hose to
one rear wheel cylinder. Submerge other end of hose into container
partially filled with brake fluid. Have assistant press and hold brake
pedal down while observing brake warning light. Open bleeder screw. If
warning light glows, switch is operating properly.
2) If warning light fails to glow, check circuit fuse, bulb
and wiring. Repair as necessary. Repeat step 1). If warning light
fails to glow, check brakelight, parking brake switches and related
wiring. Repair as necessary. Repeat step 1). If warning light fails to
glow, pressure differential switch is faulty. Replace combination
valve assembly, and bleed brake system. Verify proper valve operation.
REMOVAL & INSTALLATION