1999 DODGE RAM wiring

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-

Requested WARM boot or User-Requested COLD boot. If DRB should display
any other error message, record entire display and contact
manufacturer.
2) If DRB does not power-up, check for loose cable
connections or a bad cable. Check vehicle battery voltage (data link
connector terminal No. 16). A minimum of 11 volts is required to
adequately power DRB.
3) If all connections are proper between DRB and vehicle or
other devices, and vehicle battery is fully charged, an inoperative
DRB may be result of faulty cable or vehicle wiring.
ENTERING ON-BOARD DIAGNOSTICS
1) Before entering on-board diagnostics, refer to
PRETEST INSPECTION & DIAGNOSTIC PROCEDURE . Connect DRB to data link
connector. Data link connector (DLC) is located under left side of
instrument panel, left of steering column.
NOTE: Read active DTCs with PAD switch in both ON and OFF
positions. Always turn ignition off before changing PAD
switch positions,
2) Turn ignition switch to ON position. Exit vehicle with
DRB. Using DRB, read and record active Diagnostic Trouble Code (DTC)
data. Read and record stored DTC data. If any DTCs (fault messages)
exist, perform appropriate test.
3) If PAD switch OFF indicator fails to illuminate when in
the OFF position, go to PAD SWITCH INDICATOR PROBLEMS . If PAD switch
OFF indicator illuminates when switch is in ON position or key
cylinder does not operate, replace PAD switch.
4) Air Bag Control Module (ACM) may report any of the
following DTCs or fault messages. If the following active or stored
codes are reported by DRB, replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
* ACM OUTPUT DRIVER CIRCUIT OPEN
* ACM ACCELEROMETER
* ACM INTERNAL DIAGNOSTIC CODE #1
* WARNING LAMP DRIVER ERROR
* FIRING CAPACITOR LOW
* LOGIC CAPACITOR LOW
* SAFING SENSOR SHORTED
If the following active codes are reported by DRB, go to the
appropriate procedure under DIAGNOSTIC TESTS.
* CLUSTER MESSAGE MISMATCH
* DRIVER SQUIB CIRCUIT OPEN
* DRIVER SQUIB CIRCUIT SHORTED
* DRIVER SQUIB CIRCUIT SHORTED TO BATTERY
* DRIVER SQUIB CIRCUIT SHORTED TO GROUND
* LOSS OF IGNITION RUN ONLY
* LOSS OF IGNITION RUN/START
* NO CLUSTER CCD MESSAGE
* NO CCD COMMUNICATION
* MISSING OR INVALID VIN
* PASSENGER SQUIB CIRCUIT OPEN
* PASSENGER SQUIB CIRCUIT SHORTED
* PASSENGER SQUIB CIRCUIT SHORTED TO BATTERY
* PASSENGER SQUIB CIRCUIT SHORTED TO GROUND
* SCTM FAILURE
* SCTM MESSAGE MISMATCH
* VIN MESSAGE MISMATCH

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

Reconnect battery. Using a voltmeter, check voltage between ground and
passenger-side air bag module 2-pin connector terminals "A" and "B".
If voltage is more than 0.5 volt on either circuit, go to next step.
If voltage is less than 0.5 volt on either circuit, replace ACM.
4) Disconnect PAD switch 4-pin connector. Using a voltmeter,
check voltage between ground and passenger-side air bag module 2-pin
connector terminals "A" (Black/Yellow wire) and "B" (Dark Green/Yello\
w
wire). If voltage is more than 0.5 volt in either circuit, repair
short in Black/Yellow wire or Dark Green/Yellow wire. If voltage is
less than 0.5 volt in either circuit, go to next step.
5) Using a voltmeter, check voltage between ground and PAD
switch 4-pin connector (harness side) terminals No. 1 (Brown/Yellow
wire) and No. 2 (Violet/Yellow wire). If voltage is more than 0.5 vol\
t
on either circuit, repair short in Brown/Yellow wire or Violet/Yellow
wire. If voltage is less than 0.5 volt on either circuit, replace PAD
switch.
REPAIRING SEAT BELT CONTROL TIMER MODULE (SCTM)
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 a voltmeter, backprobe (do not disconnect connector)\
main seat connector terminal No. 10 (Light Green/Black wire) to
ground. See WIRING DIAGRAMS for terminal identification. If voltage is
between 1-3 volts, replace ACM. If voltage is less than one volt,
repair open in Light Green/Black wire. If voltage is between 9-10
volts, perform Seat Belt Control Timer Module (SCTM) diagnostics.
Repair as required. If voltage is not between 9-10 volts, go to next
step.
2) Disconnect SCTM connector. Using a voltmeter, check
voltage between ground and SCTM connector terminal No. 11 (Light
Green/Black wire). If voltage is between 9-10 volts, replace SCTM. If
voltage is not between 9-10 volts, go to next step.
3) Turn ignition off. Using an ohmmeter, check resistance
between ground and SCTM connector terminal No. 11 (Light Green/Black
wire). If resistance is less than 5 ohms, repair short in Light
Green/Black wire. If resistance is more than 5 ohms, go to next step.
4) Using an ohmmeter, check resistance between ground and
SCTM connector terminals No. 6 (Black/Light Green wire) and No. 13
(Black/Pink wire). If resistance is more than 5 ohms on either
circuit, repair open in Black/Light Green wire or Black/Pink wire. If
resistance is less than 5 ohms on either circuit, go to next step.
5) Turn ignition off. Using a voltmeter, check voltage
between ground and SCTM connector terminal No. 4 (Dark Blue wire). If
voltage is less than 10 volts, repair open in Dark Blue wire. If
voltage is more than 10 volts, go to next step.
6) Using a voltmeter, check voltage between ground and SCTM
connector terminal No. 5 (Pink wire). If voltage is less than 10
volts, repair open in Pink wire. If voltage is more than 10 volts,
replace SCTM.
REPAIRING SCTM 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

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.

WIRING DIAGRAMS
Fig. 20: Air Bag System Wiring Diagram

CTM has remote keyless entry receiver and control logic incorporated.
COMPONENT TESTS
RELAYS
NOTE: Headlight relay may also be referred to as the security
relay. On Ram Pickup, the headlight relay is located in Power
Distribution Center (PDC) in engine compartment. On Ram Van
and Ram Wagon, the headlight relay is taped to headlight
switch harness. On Ram Pickup, the horn relay is located in
Power Distribution Center (PDC) in engine compartment. On Ram\
Van and Ram Wagon, the horn relay is located in junction
block under left side of instrument panel. For circuit
testing, see WIRING DIAGRAMS.
Headlight Relay & Horn Relay
Remove relay to be tested. Measure resistance between
appropriate relay terminals with relay de-energized and energized. See
RELAY TEST SPECIFICATIONS table. See Fig. 1. If continuity or
resistance is not as specified, replace relay.
RELAY TEST SPECIFICATIONS









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Terminals Condition
De-Energized
87A & 30 .............................................. Continuity
87 & 30 ............................................ No Continuity
85 & 86 .................................... 70-80 Ohms Resistance
Energized ( 1)
87 & 30 ............................................... Continuity
87A & 30 ........................................... No Continuity
( 1) - Apply position battery voltage to terminal No. 85 and ground
terminal No. 86.









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Fig. 1: Identifying Relay Connector Terminals
Courtesy of Chrysler Corp.
SYSTEM TESTS

door lock cylinder switch pigtail retainers and remove door lock
cylinder switch. To install, reverse removal procedure.
Removal & Installation (Ram Van & Ram Wagon)
Disconnect negative battery cable. Remove inside door panel.
Disconnect door lock cylinder harness connector. Disengage door lock
cylinder switch from back of door lock cylinder. Remove door lock
cylinder switch pigtail retainers and remove door lock cylinder
switch. To install, reverse removal procedure.
Fig. 4: Identifying Door Lock Cylinder Switch (Ram Pickup)
Courtesy of Chrysler Corp.
WIRING DIAGRAMS