Wiring DODGE RAM 1999 Service Manual Online

does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article.
2) Using scan tool select BODY COMPUTER. If scan tool
displays NO RESPONSE, go to appropriate VEHICLE COMMUNICATIONS
article. If scan tool does not displays NO RESPONSE, go to next step.
3) This test is only for vehicles equipped with speed
sensitive door locks. With doors closed and unlocked drive vehicle
faster than 15 MPH. If doors lock, system is currently functioning
properly. If doors do not lock, using scan tool select ROLLING LOCKS.
Retest system.
DOORS LOCK WITH KEY IN IGNITION & LEFT 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 or connecting any module connector.
1) Using scan tool select SYSTEM MONITORS, then CCD BUS TEST.
If scan tool displays BUS OPERATIONAL, go to next step. If scan tool
does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article.
2) Using scan tool select BODY COMPUTER. 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) Place key in ignition. Open driver's door. Lock doors from
interior lock switch. If doors locked, go to next step. If doors did
not lock, system is currently functioning correctly.
4) Using scan tool, read left door ajar status. Open and
close left door. If door ajar state changed from OPEN to CLOSED, go to
next step. If door ajar state did not change from OPEN to CLOSED, go
to OPEN LEFT DOOR AJAR CIRCUIT under DOOR AJAR SYSTEM.
5) Ensure driver's door is open. Read key-in ignition status.
If scan tool shows KEY-IN, replace Central Timer Module (CTM). CTM is
located behind right kick panel. If scan tool does not show KEY-IN, go
to next step.
6) Gain access to CTM connector C1. Do not disconnect
connector. Using an external voltmeter, measure voltage between ground
and CTM 14-pin connector C1 terminal No. 9 (Light Blue wire). If
voltage is more than 1.5 volts, repair open Light Blue wire. If
voltage is 1.5 volts or less, go to next step.
7) Turn ignition off and remove key. Measure voltage between
ground and CTM 14-pin connector C1 terminal No. 9 (Light Blue wire).
If voltage is less than 1.5 volts, replace CTM. If voltage is 1.5
volts or more, replace ignition switch.
ONE OR ALL DOORS FAILING TO LOCK FROM ONE SWITCH (ONE OR ALL
DOORS FAILING TO UNLOCK FROM ONE SWITCH)
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 SYSTEM MONITORS, then CCD BUS TEST.
If scan tool displays BUS OPERATIONAL, go to next step. If scan tool
does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article.
2) Using scan tool select BODY COMPUTER. If scan tool

14) Connect test light to ground and probe Orange/Black wire
of door lock actuator connector. If test light illuminates while door
unlock switch is pressed, repair open Orange/Black wire between door
lock actuator and Central Timer Module (CTM). CTM is located behind
right kick panel. If test light does not illuminate while door unlock
switch is pressed, go to next step.
15) Access CTM 18-pin connector C2. Remove connector cover.
Do not disconnect connector. Using an external voltmeter, measure
voltage between ground and CTM 18-pin connector C2 terminal No. 9
(Pink/Black wire). If voltage is more than 9.5 volts while door unlock\
switch is pressed, repair open Pink/Black wire. If voltage is 9.5
volts or less while door unlock switch is pressed, replace CTM.
16) Disconnect inoperative lock switch connector. Using an
external voltmeter, measure voltage between ground and Red wire of
door lock switch connector. If voltage is more than 9.5 volts, repair
open Red wire between door lock switch connector and voltage source.
If voltage is 9.5 volts or less, go to next step.
17) Reconnect door lock switch connector. Measure voltage
between ground and backprobe Pink/Violet wire of door lock switch
connector. If voltage is more than 9.5 volts, go to next step. If
voltage is 9.5 volts or less, replace door lock switch.
18) Access CTM 18-pin connector "B". Remove connector cover.
Do not disconnect connector. Using an external voltmeter, measure
voltage between ground and CTM 18-pin connector "B" terminal No. 13
(Pink/Dark Green wire). If voltage is more than 9.5 volts, replace
CTM. If voltage is 9.5 volts or less, repair open Pink/Dark Green wire
between CTM and door lock switch.
REMOTE KEYLESS ENTRY PROBLEM
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 SYSTEM MONITORS, then CCD BUS TEST.
If scan tool displays BUS OPERATIONAL, go to next step. If scan tool
does not display BUS OPERATIONAL, go to appropriate VEHICLE
COMMUNICATIONS article.
2) Using scan tool select BODY COMPUTER. 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) Operate door locks with Remote Keyless Entry (RKE)
transmitter. If doors locked when transmitter was actuated, system is
currently functioning properly. If doors do not lock when transmitter
was actuated, go to next step.
4) Ensure transmitter battery voltage is 3.2 volts. Turn
ignition on. Place transmission in park and disarm anti-theft system.
Using scan tool, select MISCELLANEOUS, then PROGRAM RKE. If BCM IS IN
PROGRAMMING MODE does not appear, exit and select PROGRAM RKE again.
Press any transmitter button. A single chime will announce RKE module
accepted transmission. Repeat procedure for all transmitters used with
vehicle. Operate door locks from reprogrammed transmitter. If door
locks operate properly, system has been repaired. If door locks do not
operate properly, go to next step.
5) Using scan tool, reprogram a known good transmitter:
Operate door locks with reprogrammed transmitter. If doors locked
properly, replace transmitter. If doors did not lock properly, replace
CTM.

VEHICLE THEFT/SECURITY SYSTEM
DOOR DISARM SWITCH FAILURE
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, read VTSS inputs/outputs information. If
scan tool displays door disarm switch state OPEN, system is currently
functioning properly. If scan tool does not display door disarm switch
state OPEN, go to next step.
2) Disconnect left door disarm switch. If scan tool displays
door disarm switch state OPEN, replace left door disarm switch. If
scan tool does not display door disarm switch state OPEN, go to next
step.
3) Disconnect right door disarm switch. If scan tool displays
door disarm switch state OPEN, replace left door disarm switch. If
scan tool does not display door disarm switch state OPEN, go to next
step.
4) Access Central Timer Module (CTM). CTM is located under
left side of instrument panel. Disconnect CTM 18-pin connector C2.
Using an external ohmmeter, measure resistance between ground and CTM
18-pin connector C2 terminal No. 10 (Light Green/Orange wire). If
resistance is less than 1000 ohms, repair short to ground in Light
Green/Orange wire. If resistance is 1000 ohms or more, replace CTM.
DOOR LOCK SWITCH FAILURE
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) Clear trouble codes as needed. See BODY CONTROL COMPUTER -
INTRODUCTION article. Using scan tool, read I/O's door lock 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. 13 (Pink/Dark Green wire). If voltage\
is more than 1.5 volts, repair short to voltage in Pink/Dark Green
wire between CTM and door lock switch. If voltage is 1.5 volts or
less, replace CTM.
DOOR UNLOCK SWITCH FAILURE
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) 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

disarm switch state CLOSED, replace CTM.
23) Turn ignition switch to START position. If horn does not
sound, go to next step. If horn sounds, go to step 24).
24) Locate Central Timer Module (CTM). CTM is located behind\
right kick panel. Disconnect CTM 14-pin connector C1. Using an
external voltmeter, measure voltage between ground and CTM 14-pin
connector C1 terminal No. 8 (Dark Blue/White wire). If voltage is more\
than 10 volts, replace CTM. If voltage is 10 volts or less, repair
open Dark Blue/White wire between CTM and RUN-ACC fuse in junction
block.
WINDSHIELD WIPER SYSTEM
WIPER PARK SWITCH FAILURE
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.
NOTE: It takes 8 seconds for wiper park switch failure DTC to set.
1) Using scan tool, clear DTCs. See appropriate SELF-
DIAGNOSTICS article. Operate wipers in low speed, then intermittent
mode. Reread DTCs. If WIPER PARK SWITCH FAILURE is displayed, go to
next step. If WIPER PARK SWITCH FAILURE is not displayed, system is
currently functioning properly.
2) Gain access to wiper motor connector. Using an external
voltmeter, measure voltage between ground and wiper motor terminal No.
2 (Dark Green wire). If voltage is more than 9 volts, go to next step.\
If voltage is 9 volts or less, replace wiper motor.
3) Locate Central Timer Module (CTM). CTM is located under
left side of instrument panel. Using an external voltmeter, measure
voltage between ground and backprobe of CTM 14-pin Green connector C1
terminal No. 11 (Dark Green wire). If voltage is 9 volts or less,
replace CTM. If voltage is more than 9 volts, repair short to voltage
in Dark Green wire between CTM and wiper relay or wiper motor.
INTERMITTENT WIPERS 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) Using scan tool select CENTRAL TIMER MODULE. If scan tool
displays NO RESPONSE, go to appropriate VEHICLE COMMUNICATIONS
article. If scan tool displays any CCD bus failure message, go to
SYMPTOM IDENTIFICATION. If scan tool does not display NO RESPONSE or
any CCD bus failure message, go to next step.
2) If problem is wipers parking in wrong position, go to next
step. If problem is not wipers parking in wrong position, go to step
5).
3) Gain access to wiper motor connector. Turn wipers on to
low speed. Using an external voltmeter, measure voltage between ground
and wiper motor switch terminal No. 2 (Dark Green wire). If voltage
does not cycle between zero and 12 volts, replace wiper motor. If
voltage cycles between zero and 12 volts, go to next step.

4) Locate Central Timer Module (CTM). CTM is located under
left side of instrument panel. Using an external voltmeter, measure
voltage between ground and backprobe of CTM 14-pin Green connector C1
terminal No. 11 (Dark Green wire). Wipers should be operating at low
speed. If voltage does not cycle between zero and 12 volts, repair
open Dark Green wire between CTM and wiper relay or wiper motor. If
voltage cycles between zero and 10 volts, replace CTM.
5) Using scan tool, monitor intermittent wiper voltage level.
Rotate wiper switch from low intermittent to high intermittent level.
If voltage changes from approximately 2.5 to 12 volts, replace CTM. If
voltage does not change from approximately 2.5 to 12 volts, go to next
step.
6) Disconnect 24-pin multifunction switch connector. Using an
external ohmmeter, measure resistance of White/Dark Blue wire between
multifunction switch connector terminal No. 1 and CTM 14-pin Green
connector C1 terminal No. 12. if resistance is less than 5 ohms,
replace multifunction switch. If resistance is 5 ohms or more, repair
open White/Dark Blue wire between multifunction switch and CTM.
NO WIPER ACTUATION AFTER WASH BUTTON PUSHED
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 Central Timer Module (CTM). If sca\
n
tool displays NO RESPONSE, go to appropriate VEHICLE COMMUNICATIONS
article. If scan tool displays any CCD bus failure message, go to
SYMPTOM IDENTIFICATION. If scan tool does not display NO RESPONSE or
any CCD bus failure message, go to next step.
2) Turn ignition on. If washer system works, go to next step.
If washer system does not work, see appropriate WIPER/WASHER SYSTEMS
article.
3) Using scan tool, actuate washer. If washer pump sense
displays ON, replace CTM. If washer pump sense does not display ON,
repair open Brown wire between CTM 14-pin connector C1 terminal No. 10
and multifunction switch.
WIPER SPEED SENSITIVE FEATURE 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) Using scan tool select Central timer module (CTM). If sca\
n
tool display is not blank or have a CCD bus failure message, go to
next step. If scan tool display is blank or has a CCD bus failure
message, see appropriate VEHICLE COMMUNICATIONS article.
2) Using scan tool, select Powertrain Control Module (PCM).
If scan tool display is not blank or have a CCD bus failure message,
go to next step. If scan tool display is blank or has a CCD bus
failure message, see appropriate VEHICLE COMMUNICATIONS article.
3) Raise and support vehicle. Turn wipers on to lowest
intermittent position. Time interval between wipes. Spin rear wheels
to more than 15 MPH. If interval between wipes decreased to
approximately 18 seconds, system is currently functioning properly. If
interval between wipes did not decrease to approximately 18 seconds,

SHOE HARDWARE
SHOES
SOCKETS
SPEED SENSORS (ELECTRONIC WHEEL AND VEHICLE)
STEEL BRAKE LINES
STOPLIGHT SWITCHES
SWITCHES
TIRES
TOOTHED RINGS (TONE WHEEL)
VACUUM BOOSTERS
VACUUM HOSES
VALVES
WHEEL ATTACHING HARDWARE
WHEEL BEARINGS, RACES AND SEALS
WHEEL CYLINDERS
WIRING HARNESSES
INTRODUCTION TO MOTORIST ASSURANCE PROGRAM (MAP)
OVERVIEW OF MOTORIST ASSURANCE PROGRAM
The Motorist Assurance Program is the consumer outreach
effort of the Automotive Maintenance and Repair Association, Inc.
(AMRA). Participation in the Motorist Assurance Program is drawn from
retailers, suppliers, independent repair facilities, vehicle
manufacturers and industry associations.
Our organization's mission is to strengthen the relationship
between the consumer and the auto repair industry. We produce
materials that give motorists the information and encouragement to
take greater responsibility for their vehicles-through proper,
manufacturer-recommended, maintenance. We encourage participating
service and repair shops (including franchisees and dealers) to adopt:\
1) a Pledge of Assurance to their Customers and
2) the Motorist Assurance Program Standards of Service.
All participating service providers have agreed to subscribe
to this Pledge and to adhere to the promulgated Standards of Service
demonstrating to their customers that they are serious about customer
satisfaction.
These Standards of Service require that an inspection of the
vehicle's (problem) system be made and the results communicated to the\
customer according to industry standards. Given that the industry did
not have such standards, the Motorist Assurance Program successfully
promulgated industry inspection communication standards in 1994-95 for
the following systems: Exhaust, Brakes, ABS, Steering and Suspension,
Engine Maintenance and Performance, HVAC, and Electrical Systems.
Further, revisions to all of these inspection communication standards
are continually re-published. In addition to these, standards for
Drive Train and Transmissions have recently been promulgated.
Participating shops utilize these Uniform Inspection & Communication
Standards as part of the inspection process and for communicating
their findings to their customers.
The Motorist Assurance Program continues to work
cooperatively and proactively with government agencies and consumer
groups toward solutions that both benefit the customer and are
mutually acceptable to both regulators and industry. We maintain the
belief that industry must retain control over how we conduct our
business, and we must be viewed as part of the solution and not part
of the problem. Meetings with state and other government officials
(and their representatives), concerned with auto repair and/or
consumer protection, are conducted. Feedback from these sessions is
brought back to the association, and the program adjusted as needed.
To assure auto repair customers recourse if they were not

and make an informed decision about how to proceed.
BRAKES
SERVICE PROCEDURES REQUIRED & SUGGESTED FOR PROPER
VEHICLE OPERATION
Some states may have specifications that differ from OEM.
Check your local/state regulations. Where state or local laws are
stricter, they take precedence over these guidelines.
ACCELEROMETERS (G SENSOR OR LATERAL)
ACCELEROMETER INSPECTION








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Condition Code Procedure
Broken .................. A ............ Require replacement.
Connector loose ......... A .. Require repair or replacement.
Loose ................... B .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Out of position ......... B ....... Require re-positioning to
vehicle manufacturer's
specifications.
Output signal incorrect . B ............ Require replacement.









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ACCUMULATORS
ACCUMULATOR INSPECTION








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Condition Code Procedure
Leaking ................. B ............ Require replacement.
Missing ................. C ............ Require replacement.
Pre-charge incorrect .... B ............ Require replacement.









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ANCHOR PINS
See BACKING PLATES .
ANTI-LOCK BRAKE SYSTEMS
NOTE: Anti-lock brakes are an integral part of the brake system. It
is essential that the anti-lock brakes function properly when
brake service is performed.
Anti-lock brake systems are commonly referred to as "ABS" and
will be referred to as "ABS" throughout these guidelines. Some ABS
components also function as part of a traction control system (TCS).
WARNING: When diagnosing and servicing high pressure components,
observe safety procedures and equipment requirements
established by the vehicle manufacturer to reduce the
possibility of serious personal injury.
NOTE: Intermittent electrical conditions are often caused by a loss
of ground, poor connection, or water intrusion into the
wiring harness.

(3) - Inspect for conditions related to wheel cylinder.
( 4) - Leaking is defined as a drop or more. Dampness is normal.









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WIRING HARNESSES
NOTE: Copied from Electrical UIGs.
WIRING HARNESS INSPECTION









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Condition Code Procedure
Application incorrect ... B .. Require repair or replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted ........ A ........... ( 1) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.
Insulation damaged,
conductors exposed ..... A .. Require repair or replacement.
Insulation damaged,
conductors not exposed . 1 ............ Suggest replacement.
Open .................... A .. Require repair or replacement.
Protective shield
(conduit) melted ....... 2 ........... ( 1) Suggest repair or
replacement.
Protective shield
(conduit) missing ...... 2 .. Suggest repair or replacement.
Resistance (voltage drop)
out of specification ... A .. Require repair or replacement.
Routed incorrectly ...... B ................. Require repair.
Secured incorrectly ..... B ................. Require repair.
Shorted ................. A .. Require repair or replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Voltage drop out of
specification .......... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.









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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