fuse DODGE RAM 1999 Service User Guide

controls to A/C. Start and operate engine at idle speed.
3) Using an ohmmeter, check for continuity between switch
terminals. Continuity should exist when suction pressure reading is
above 38 psi (2.7 kg/cm
) on Dakota; 43 psi (3.0 kg/cm) on Ram
Pickup. Continuity should not exist when suction pressure reading
drops below 20.5 psi (1.4 kg/cm
) on Dakota; 25 psi (1.8 kg/cm) on
Ram Pickup. If switch is okay, test and repair clutch control circuit
as needed. If switch is not okay, replace faulty clutch cycling
pressure switch.
ELECTRONIC CYCLING CLUTCH SWITCH
Durango
1) Locate electronic cycling clutch switch on thermal
expansion valve in engine compartment. Ensure system pressure is
correct. See A/C SYSTEM PERFORMANCE test. Ensure low pressure cut-out
switch and high pressure cut-out switch are working properly. See
LOW PRESSURE CUT-OUT SWITCH TEST and HIGH PRESSURE CUT-OUT SWITCH
test.
2) Disconnect negative battery cable. Disconnect electronic
cycling clutch switch and high pressure cut-out switch connectors.
Using an ohmmeter, check for continuity in Light Green/White wire
between electronic cycling clutch switch and high pressure cut-out
switch. If continuity exists in Light Green/White wire, go to next
step. If continuity does not exist in Light Green/White wire, repair
wire as necessary.
3) Disconnect low pressure cut-out switch connector. Using an
ohmmeter, check for continuity in Dark Blue/Yellow wire between
electronic cycling clutch switch and low pressure cut-out switch. If
continuity exists in Dark Blue/Yellow wire, go to next step. If
continuity does not exist in Dark Blue/Yellow wire, repair wire as
necessary.
4) Connect low pressure cut-out switch and high pressure cut-
out switch connectors. Connect negative battery cable. Turn ignition
on. Using voltmeter, check for battery voltage at electronic cycling
clutch switch connector terminal No. 2 (White wire). If battery
voltage exists, go to step 6).
5) If battery voltage does not exist, check fuse No. 7 (15-
amp) at junction block located at bottom left of instrument panel. If
fuse is okay, check for short or open in White wire between electronic
cycling clutch switch connector and fuse No. 7 (15-amp) at junction
block.
6) Connect electronic cycling clutch switch connector. Ensure
ambient temperature is between 68-90
F (20-30C). Start engine and
turn A/C on. If compressor clutch cycles 2-3 times per minute, replace
faulty electronic cycling clutch switch. If compressor clutch does not
cycle, check PCM for proper operation. See appropriate G - TESTS
W/CODES article in ENGINE PERFORMANCE section.
HIGH PRESSURE CUT-OUT SWITCH
1) Locate high pressure cut-out switch on compressor
discharge line, near compressor. Ensure system pressure is correct.
See A/C SYSTEM PERFORMANCE test. Disconnect negative battery cable.
Disconnect high pressure cut-off switch connector.
2) Using an ohmmeter, check for continuity between switch
terminals. If continuity exists, test and repair clutch control
circuit as needed. If continuity does not exist, replace faulty
switch.
LOW PRESSURE CUT-OUT SWITCH TEST
Durango


A/C -H EA TE R S YSTE M T R O UBLE S H O OTIN G

1999 D odge P ic ku p R 1500
1999 MANUAL A/C-HEATER SYSTEMS
Trouble Shooting - Cars & Trucks
CHRYSLER
Avenger, Breeze, Caravan, Cirrus, Concorde, Dakota, Durango,
Intrepid, LHS, Neon, Ram Pickup, Ram Van/Wagon, Sebring Convertible,
Sebring Coupe, Stratus, Town & Country, Voyager, 300M
A/C SYSTEM DIAGNOSIS
RAPID COMPRESSOR CLUTCH CYCLING
Some possible causes of rapid compressor clutch cycling,
clutch cycles 10 or more times per minute, include:
* Low refrigerant system charge.
* Faulty low pressure cycling clutch switch.
* Faulty PCM.
COMPRESSOR WILL NOT ENGAGE
Some possible causes of compressor not engaging with high and
low side system pressures equal include:
* No refrigerant in system.
* Faulty fuse.
* Faulty compressor clutch coil.
* Faulty compressor clutch relay.
* Faulty electronic cycling clutch switch.
* Improperly installed or faulty low pressure cycling clutch
switch.
* Faulty low pressure cut-off switch.
* Faulty high pressure cut-off switch.
* Faulty PCM.
* Faulty A/C-heater control panel.
TEMPERATURE IS TOO HIGH WITH A/C ON
Some possible causes of high temperature output at center
panel when A/C system pressure is normal include:
* Excessive oil charge in refrigerant.
* Temperature control cable improperly installed or faulty.
* Blend-air door inoperative, obstructed or sealing
improperly.
* Blend door actuator not calibrated.
LOW SIDE PRESSURE IS LOW-TO-NORMAL & HIGH SIDE PRESSURE IS
LOW
Some possible causes of low side system pressure being lower-
to-normal and high side system pressure being too low include:
* Low refrigerant system charge.
* Refrigerant flow through accumulator is restricted.
* Refrigerant flow through evaporator is restricted.
* Faulty compressor.
LOW SIDE PRESSURE IS HIGH-TO-NORMAL & HIGH SIDE PRESSURE IS

HIGH
Some possible causes of low side system pressure being high-
to-normal and high side system pressure being too high include:
* Condenser air flow restricted.
* Inoperative cooling fan.
* Faulty expansion valve.
* Refrigerant system overcharged.
* Air in refrigerant system.
* Engine overheating.
LOW SIDE PRESSURE IS HIGH & HIGH SIDE PRESSURE IS LOW
Some possible causes of low side system pressure being too
high and high side system pressure being too low include:
* Compressor belt is slipping.
* Fixed orifice tube not installed.
* Faulty compressor.
LOW SIDE PRESSURE IS LOW & HIGH SIDE PRESSURE IS HIGH
Some possible causes of low side system pressure being too
low and high side system pressure being too high include:
* Restricted refrigerant flow through refrigerant lines.
* Restricted refrigerant flow through expansion valve.
* Restricted refrigerant flow through fixed orifice tube.
* Restricted refrigerant flow through receiver-drier.
* Restricted refrigerant flow through condenser.
BLOWER MOTOR DIAGNOSIS
BLOWER MOTOR INOPERATIVE
Some possible causes of an inoperative blower motor include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor ground circuit wire harness or
connector.
* Faulty blower motor resistor.
* Faulty blower motor relay.
* Faulty blower motor switch.
* Faulty A/C-heater mode control switch.
* Faulty blower motor.
BLOWER NOT OPERATING IN ALL SPEEDS
Possible causes of the blower not operating in all speeds
include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor relay.
* Faulty blower motor resistor.
* Faulty blower motor switch.

protective cover is fitted to front of air bag module bearing the SRS
air bag logo. Air bag module contains air bag cushion, inflator and
supporting components. Air bag module is a sealed unit and is not
serviceable. The module inflator assembly produces nitrogen gas to
fill air bag cushion when a small amount of current from ACM is
applied to the ignitor assembly. Gas pressure builds and discharges
from inflator through a diffuser and screen assembly, forcing steering
wheel cover to burst along its seams until air bag is fully inflated.
Once air bag cushion is fully inflated, gas escapes from bag through
vents, away from driver.
Passenger-Side
Air bag module is mounted to instrument panel mounting
bracket. Module is covered by a protective door bearing the SRS air
bag logo. When supplied an electrical signal, inflator will discharge
argon gas directly into air bag. When air bag inflates, protective
door will pivot aside allowing air bag to deploy.
AIR BAG CONTROL MODULE (ACM)
ACM is located under instrument panel, on transmission
tunnel. Impact sensor, energy reserve capacitor and On-Board
Diagnostics (OBD) are an integral part of ACM. ACM monitors critical
input and output circuits within air bag system, ensuring they are
operating correctly. Some circuits are tested continuously; others are
checked only under certain conditions. ACM provides information about
air bag system through AIR BAG warning light and Data Link Connector
(DLC). When diagnostic trouble code (fault message) is stored, AIR B\
AG
warning light will be activated for 12 seconds or more.
DATA LINK CONNECTOR (DLC)
DLC is located under left side of instrument panel, left of
steering column. DLC is used to access SRS on-board diagnostics.
CLOCKSPRING
Clockspring connects air bag module to steering column
wiring, completing air bag system circuit. See Fig. 1. Inside
clockspring is a flat, ribbon-like tape of conductive material, which
winds and unwinds with steering wheel movement. Clockspring is the
most fragile part of air bag system. Clockspring must be centered
properly to allow 1 1/2 steering wheel turns in either direction. If
clockspring is not centered properly, it can break from stretching or
fatigue.
Fig. 1: Identifying Clockspring Assembly
Courtesy of DaimlerChrysler Corp.

(ACM), use wire side (not terminal end) of connector.
* DO NOT probe a wire through insulator, as this will damage
it and eventually cause failure.
* When performing electrical tests, prevent accidental
shorting of terminals. Such shorts can damage fuses or
components and may cause a second fault code to set, making
diagnosis of original problem more difficult.
* When diagnosing air bag system, use DRB volt/ohmmeter
unless instructed to use an external volt/ohmmeter. NEVER
use an analog volt/ohmmeter or test light in place of a
digital volt/ohmmeter.
* When using DRB to diagnose an air bag system problem,
operate DRB from outside of vehicle. DO NOT sit inside of
vehicle.
* Never use an ohmmeter to measure resistance of air bag
module. Accidental air bag deployment may occur, causing
personal injury.
* If air bag system is not fully functional for any reason,
vehicle should not be driven until system is repaired and
again becomes operational. DO NOT remove bulbs, modules,
sensors, or other components or in any way disable system
from operating normally. If air bag system is not
functional, park vehicle until it is repaired and functions
properly.
* 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 in GENERAL INFORMATION
before disconnecting battery.
DISABLING & ACTIVATING AIR BAG SYSTEM
WARNING: Wait at least 2 minutes after disconnecting negative battery
cable before servicing air bag system. System reserve
capacitor, integral to ACM, maintains air bag system voltage
for about 2 minutes after battery is disconnected. Servicing
air bag system before 2-minute period may cause accidental
deployment of air bag(s) and possible personal injury. DO NOT\
use computer system memory saving devices. Enough voltage to
deploy air bag(s) may be provided from device.
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 in GENERAL INFORMATION
before disconnecting battery.
Disabling System
To disable air bag system for repairs, ensure ignition switch
is in OFF position. Disconnect and shield negative battery cable.
After disconnecting negative battery cable, wait at least 2 minutes
for reserve capacitor to discharge before servicing air bag system.
Activating System
Reconnect negative battery cable. From a position clear of air bag(s),\
turn ignition on. Perform system operation check. See
SYSTEM OPERATION CHECK .
DISPOSAL PROCEDURES
DEPLOYED AIR BAG CLEAN-UP

as the malfunction is detected. A stored code indicates there was an
active code present at some time. However, the code currently may not
be present as an active code, although another active code could be.
When a trouble code occurs, the AIR BAG warning light
illuminates for 12 seconds minimum (even if problem existed for less
than 12 seconds). Code is stored, along with time in minutes it was
active, and number of times ignition has been cycled since problem was
detected.
When and if malfunction ceases to exist, an ignition cycle
count will be initiated for that code. If ignition cycle count reaches
100 without a reoccurrence of the same malfunction, DTC is erased and
that ignition cycle counter is reset to zero. If malfunction reoccurs
before count reaches 100, ignition cycle counter will be reset and DTC
will continue to be a stored code.
If a particular code is not active while performing
diagnostic test for that code, code diagnostic test may not locate the
source of the problem. In this case, stored code can only indicate an
area of system to inspect.
If no obvious problems are found, erase stored codes, and
with ignition on, wiggle wiring harness and connectors. Recheck for
codes periodically as you work through system. This procedure may
uncover a difficult problem to locate.
PRETEST INSPECTION & DIAGNOSTIC PROCEDURE
Following precautions and procedures must be followed:
* Always follow air bag service precautions to avoid air bag
deployment and possible personal injury. Refer to procedure
under See SERVICE PRECAUTIONS.
* After component replacement, ensure proper system operation.
See SYSTEM OPERATION CHECK .
* When testing voltage or continuity at ACM, use terminal side
(not wire end) of connector. DO NOT probe wire through
insulation.
* Always check if any TECH SERVICE BULLETINS (TSBs) apply to
vehicle.
* When using diagnostic charts, DO NOT skip any steps in chart
or incorrect diagnosis may result. Always perform
SYSTEM OPERATION CHECK after repairs are made.
* Always use most current DRB diagnostic program cartridge
available to prevent erroneous codes or test results.
* When using diagnostic charts, use DRB voltmeter unless
instructed to use an external voltmeter. Never use a test
light in place of a voltmeter.
* When performing electrical tests, prevent accidental
shorting of terminals. Such shorts can damage fuses or
components and may cause a second code (message) to be
set, making diagnosis of original problem more difficult.
* Vehicle must have a fully-charged battery and functional
charging system.
* 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.
* Always disconnect DRB after use.
* Always disconnect DRB before charging battery.
USING DRB
1) Refer to DRB user guide for instructions and assistance
with reading trouble codes and other DRB functions. Under normal
operation DRB will display one of only 2 error messages: User-

Fig. 17: Identifying Fuses & Junction Block
Courtesy of DaimlerChrysler Corp.

more than 5 ohms on either circuit, repair short to ground in Dark
Green/Light Blue wire or Black/Light Blue wire. If resistance is less
than 5 ohms on either circuit, go to next step.
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.
LOSS OF IGNITION RUN ONLY
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) Remove and inspect fuse No. 18 located in junction block.
If fuse is blown, go to step 5). If fuse is good, go to next step.
2) Using a voltmeter, check voltage between ground and
ignition switch output RUN circuit at fuse No. 18. If voltage is less
than 10 volts, repair open ignition switch output RUN circuit. If
voltage is more than 10 volts, go to next step.
3) Reinstall fuse No. 18. Disconnect battery and wait 2
minutes before proceeding. Disconnect ACM connector. Turn ignition on,
then reconnect battery. Using a voltmeter, check voltage between
ground and ACM connector terminal No. 15 (Dark Blue/Yellow wire). If
voltage is more than 10 volts, go to next step. If voltage is less
than 10 volts, repair open in Dark Blue/Yellow wire.
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.
5) Turn ignition off. Using an ohmmeter, check resistance
between ground and fused ignition switch output RUN circuit at fuse
No. 18. If resistance is more than 5 ohms, replace fuse No. 18 located
in junction block. If resistance is less than 5 ohms, go to next step.
6) Disconnect battery and wait 2 minutes before proceeding.
Disconnect ACM connector. Using an ohmmeter, check resistance between
ground and ACM connector terminal No. 15 (Dark Blue/Yellow wire). If
resistance is less than 5 ohms, repair fused ignition switch output
RUN circuit for a short to ground and replace fuse. If resistance is
more than 5 ohms, go to next step.
7) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM and fuse No. 18. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
LOSS OF IGNITION RUN/START
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) Remove and inspect fuse No. 19. If fuse is blown, go to
step 5). If fuse is good, go to next step.
2) Using a voltmeter, measure ignition switch output
RUN/START circuit between fuse No. 19 and ground. If voltage is less
than 10 volts, repair open ignition switch output RUN/START circuit.
If voltage is more than 10 volts, reinstall fuse No. 19. Disconnect
battery and wait 2 minutes before proceeding. Go to next step.
3) Disconnect ACM connector. Turn ignition on. Reconnect
battery. Using a voltmeter, check voltage between ground and ACM

connector terminal No. 14 (Light Green/Yellow wire). If voltage is
less than 10 volts, repair open in Light Green/Yellow wire. If voltage
is more than 10 volts, replace ACM.
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.
5) Turn ignition off. Turn PAD switch to the ON position (if
equipped). Using an ohmmeter, check resistance at fused ignition
switch output RUN/START circuit between fuse No. 19 and ground. If
resistance is more than 5 ohms, replace fuse. If resistance is less
than 5 ohms, disconnect battery and wait 2 minutes before proceeding.
Disconnect ACM connector. Using an ohmmeter, check resistance between
ground and ACM connector terminal No. 14 (Light Green/Yellow wire). If\
resistance is less than 5 ohms, go to next step. If resistance is more
than 5 ohms, replace ACM and fuse No. 19.
6) Disconnect PAD switch. Using an ohmmeter, check resistance
between ground and ACM connector terminal No. 14 (Light Green/Yellow
wire). If resistance is less than 5 ohms, repair short to ground in
Light Green/Yellow wire and replace fuse No. 19. If resistance is more
than 5 ohms, replace fuse No. 19 located in junction block and go to
next step.
7) 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.
MISSING OR INVALID VIN MESSAGE
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) Using DRB, select ENGINE PCM. If DRB displays NO RESPONSE
from PCM, go to NO RESPONSE FROM POWERTRAIN CONTROL MODULE under
VEHICLE COMMUNICATIONS. If DRB does not display NO RESPONSE from PCM
and vehicle is a Club Cab (BE) model, go to next step. If vehicle is
not a Club Cab (BE model), go step 3).
2) Using DRB, select PASSIVE RESTRAINTS, AIRBAG AND MONITORS.
Select VIN type (7th digit of VIN; VIN 2 or 3 on Club Cab). If DRB
does not display PCM VIN: BE, replace Powertrain Control Module (PCM).\
If DRB displays PCM VIN: BE, replace ACM.
3) Using DRB, select PASSIVE RESTRAINTS, AIRBAG AND MONITORS.
Select VIN type (7th digit of VIN; VIN 6 on Standard Cab). If DRB does\
not display PCM VIN: BR, replace Powertrain Control Module (PCM). If
DRB displays PCM VIN: BR, replace ACM.
NO CCD COMMUNICATION
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.
Using DRB, read active codes. If DRB displays NO CCD
COMMUNICATION as an active code, replace ACM. If DRB does not display
NO CCD COMMUNICATION as an active code, go to
REPAIRING STORED TROUBLE CODES .
NO CLUSTER CCD MESSAGE

3) Using DRB, read stored codes. If DRB displays stored
codes, perform appropriate diagnostic test. If DRB does not display
any stored codes, system is operating properly at this time.
COMPONENT VERIFICATION TEST
Reconnect all previously disconnected components and
connectors. Turn ignition on (engine off). Fully operate system that
was malfunctioning. If system operates properly, repair is complete.
If system does not operate properly, go to appropriate diagnostic
test.
VEHICLE COMMUNICATIONS
VEHICLE COMMUNICATION PROBLEMS
NOTE: Use this test only when instructed to do so by another
diagnostic test. Due to manufacturer changes in wire
colors, use terminal identification whenever possible.
DRB Blank Screen
If DRB Screen is blank, disconnect DRB from data link
connector. Ensure good ground exists at data link connector terminal
No. 4 (Black/Tan wire). Ensure 12-volts exists at data link connector
terminal No. 16 (Pink wire). If 12-volts does not exist, check for
blown fuse No. 12 located in power distribution center. If no problems
can be found, try a different DRB cable and/or a different DRB.
No Response Condition
If no response condition from Air Bag Control Module (ACM)
exists, go to NO RESPONSE FROM AIR BAG CONTROL MODULE .
NO RESPONSE FROM AIR BAG CONTROL MODULE
NOTE: Perform COMPONENT VERIFICATION TEST under DIAGNOSTIC TESTS
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) Remove and inspect fuse No. 19. If fuse is blown, go to
OPEN FUSED IGNITION SWITCH OUTPUT (RUN/START) CKT . If not, go to next
step.
2) Using a voltmeter, measure ignition switch output
RUN/START at fuse No. 19. See WIRING DIAGRAMS. If voltage is more than
10 volts, go to next step. If voltage is less than 10 volts, repair
open ignition switch output RUN/START circuit.
3) Turn ignition off and wait 2 minutes. Disconnect ACM
connector. Reinstall fuse No. 19. Turn ignition on (engine off). Using\
a voltmeter, check voltage at ACM connector terminal No. 14 (Light
Green/Yellow wire). If voltage is more than 10 volts, go to next step.
If voltage is less than 10 volts, repair open in Light Green/Yellow
wire.
4) Turn ignition off. Using DRB in ohmmeter mode, check
resistance at ACM connector terminal No. 4 (Black/Pink wire). If
resistance is more than 5 ohms, repair open in Black/Pink wire. If
resistance is less than 5 ohms, go to next step.
5) Turn ignition on (engine off). Using DRB in voltmeter
mode, check voltage at ACM connector terminal No. 21 (Violet/Brown
wire). If voltage is 1.8-2.6 volts, go to next step. If voltage is not
1.8-2.6 volts, repair open in Violet/Brown wire.