1999 DODGE RAM battery

operator's foot off accelerator pedal, S/C compensates for excessive
S/C cable slack. If lift foot sets are continually used, speed control
overshoot/undershoot condition will develop.
To "unlearn" overshoot/undershoot condition, operator must
press and release set button while maintaining desired speed with
accelerator pedal, then turn S/C switch to OFF position after waiting
10 seconds. This procedure must be repeated 10-15 times to completely
unlearn overshoot/undershoot condition.
COMPONENT TESTS
WARNING: Vehicle is equipped with an air bag. Air bag must be
deactivated before servicing speed control components on or
around steering column. See appropriate AIR BAG RESTRAINT
SYSTEMS article.
NOTE: For component locations, See COMPONENT LOCATIONS. For
connector terminal identification, see CONNECTOR
IDENTIFICATION. For wiring diagram, see WIRING DIAGRAMS.
BRAKE SWITCH
Disconnect brake switch 6-pin connector. Using an ohmmeter,
check for continuity at brake switch. See Fig. 1. If continuity is not
as specified in BRAKE SWITCH CONTINUITY table, check brake switch
adjustment. See BRAKE SWITCH under REMOVAL & INSTALLATION. If brake
switch adjustment is okay, replace defective brake switch.
BRAKE SWITCH CONTINUITY








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Switch Plunger  Check Between  Continuity 


Position  Terminals  










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Released  5 & 6  Yes 










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Depressed  1 & 2  Yes 











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 3 & 4  Yes 











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SPEED CONTROL SERVO
1) Start engine. Disconnect Speed Control (S/C) servo 4-pin
connector. Turn S/C on. Using a voltmeter, check voltage at S/C servo
connector terminal No. 3 (Dark Blue/Red wire). Battery voltage should
exist when brake pedal is not depressed. If battery voltage exists, go
to next step. If battery voltage does not exist, check circuit between
brake switch and S/C servo. See WIRING DIAGRAMS.
2) Connect a jumper wire between S/C servo pin No. 3 and S/C
servo connector terminal No. 3. Check voltage at S/C servo pins No. 1,
2 and 4. If battery voltage does not exist, replace S/C servo. If
battery voltage exists, go to next step.
3) Turn ignition off. Check for continuity between S/C servo
connector terminal No. 4 and ground. If continuity exists, test is
complete. If continuity does not exist, repair open ground circuit as
necessary.
VACUUM SUPPLY
Gasoline Engines
1) Disconnect vacuum hose at speed control servo. Install
vacuum gauge to disconnected vacuum hose. Start engine and observe

made.
* When using a jumper wire, ensure either jumper wire or
circuit is fuse-protected.
* Before disconnecting connector from any control module,
ensure ignition is off before removing connector.
* When checking voltage or continuity at any control module,
probe connector for control module from pin side. DO NOT
backprobe connector or probe wires through insulation.
* DO NOT cause short circuits when performing electrical tests.
This will set additional Diagnostic Trouble Codes (DTCs),
making diagnosis of original problem more difficult.
* Use specified test equipment when performing electrical
tests.
RETRIEVING DIAGNOSTIC TROUBLE CODES
NOTE: Self-diagnostic tests are written specifically for Chrysler's
Diagnostic Readout Box (DRB). If using a generic scan tool,
ensure it is OBD-II certified. A generic scan tool may not be
capable of performing all necessary test functions.
Ensure battery is fully charged. Turn ignition off. Connect
scan tool to Data Link Connector (DLC). DLC is located under left side\
of instrument panel. Turn ignition on. Using scan tool manufacturer's
instructions, record all DTCs displayed on scan tool. If ant DTCs are
retrieved, perform appropriate test under DIAGNOSTIC TESTS. Once all
repairs are made, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES.
If no DTCs are retrieved and fault still exists, go to CHECKING SPEED
CONTROL OPERATION under SYSTEM TESTS.
CLEARING DIAGNOSTIC TROUBLE CODES
Ensure ignition is off. Connect scan tool to DLC. Turn
ignition on. Using screen prompts on scan tool, erase DTCs from PCM.
DIAGNOSTIC TESTS
FTC P0720: LOW OUTPUT SPEED SENSOR (OSS) RPM MORE THAN 15 MPH
FTC P0720 will set if output shaft speed is less than 60 RPM
for 2.6 seconds when vehicle speed is more than 15 MPH.
Possible Causes:
* Defective Output Speed Sensor (OSS).
* OSS signal circuit open or shorted.
* OSS ground circuit open or shorted.
* Park/Neutral Position (PNP) switch FTC present.
* Defective PNP switch.
* Defective PCM.
1) Turn ignition on. Using scan tool, read DTCs. If FTC
specific good trip is displayed and equal to zero, go to next step. If
FTC specific good trip is equal to more than zero, go to step 13).
2) If there are any Park/Neutral Position (PNP) switch DTCs,\
repair PNP switch FTC first. Perform TEST VER-5A under VERIFICATION
TESTS. If there are no PNP switch DTCs, go to next step.
3) Using scan tool, read PNP switch state. While observing
scan tool, shift transmission through all positions. If scan tool did
not display P/N and D/R in correct positions, repair PNP switch or
circuit as necessary. Perform TEST VER-5A under VERIFICATION TESTS. If

scan tool displayed P/N and D/R in correct positions, go to next step.
4) Raise drive wheels and support vehicle, allowing wheels to
spin. Using scan tool, erase DTCs. Start engine. Using scan tool, read
Output Speed Sensor (OSS). Shift transmission into first gear. While
observing scan tool, allow wheels to spin at a speed less than 15 MPH.
If scan tool displays OSS more than 60 RPM, go to next step. If scan
tool displays OSS 60 RPM or less, go to step 7).
5) While wheels are spinning, wiggle wiring between OSS and
PCM. If OSS reading dropped while wiggling, repair intermittent short
or open circuit. Perform TEST VER-5A under VERIFICATION TESTS. If OSS
reading did not drop, go to next step.
6) Using scan tool, erase DTCs. Road test vehicle. Read DTCs.
If FTC P0720 returns, replace PCM. Perform TEST VER-5A under
VERIFICATION TESTS. If FTC P0720 did not return, go to step 13).
7) Turn ignition off. Disconnect PCM. Inspect connectors.
Clean or repair as necessary. Using an ohmmeter, measure resistance
between ground and OSS signal circuit at PCM connector C2, terminal
No. 28 (Light Green/Black wire on Ram Pickup; Light Green/White wire
on all other models). If resistance is less than 5 ohms, repair short
to ground. Perform TEST VER-5A under VERIFICATION TESTS.
8) Using an ohmmeter, measure resistance between ground and
OSS ground circuit at PCM connector C2, terminal No. 25 (Dark
Blue/Black wire). If resistance is less than 5 ohms, repair short to
ground. Perform TEST VER-5A under VERIFICATION TESTS. If resistance is
5 ohms or more, go to next step.
9) Disconnect OSS. Using an ohmmeter, measure resistance
across OSS terminals. If resistance is not 300-1200 ohms, replace OSS.
Perform TEST VER-5A under VERIFICATION TESTS. If resistance is 300-
1200 ohms, go to next step.
10) Using an ohmmeter, measure resistance of OSS signal
circuit between PCM connector C2, terminal No. 28 and OSS connector
(Light Green/Black wire on Ram Pickup; Light Green/White wire on all
other models). If resistance is more than 5 ohms, repair open circuit.
Perform TEST VER-5A under VERIFICATION TESTS. If resistance is 5 ohms
or less, go to next step.
11) Using an ohmmeter, measure resistance of OSS ground
circuit between PCM connector C2, terminal No. 25 and OSS connector
(Dark Blue/Black wire). If resistance is more than 5 ohms, repair open\
circuit. Perform TEST VER-5A under VERIFICATION TESTS. If resistance
is 5 ohms or less, go to next step.
12) Reconnect OSS. Using an ohmmeter, measure resistance
between PCM connector C2, terminals No. 25 (Dark Blue/Black wire) and
No. 28 (Light Green/Black wire on Ram Pickup; Light Green/White wire
on all other models). If resistance is 300-1200 ohms, replace PCM.
Perform TEST VER-5A under VERIFICATION TESTS. If resistance is not
300-1200 ohms, go to next step.
13) Inspect wiring and connectors. repair as necessary.
Perform TEST VER-5A under VERIFICATION TESTS. If wiring and connectors
are okay, go to next step.
14) Conditions required to set FTC are not present at this
time. Check freeze frame data to determine conditions when FTC was
set. Raise drive wheels and support vehicle, allowing wheels to spin.
Using scan tool, read OSS. Shift transmission into first gear. While
observing scan tool, allow wheels to spin at a speed less than 15 MPH.
Wiggle wiring between OSS and PCM. If OSS reading dropped while
wiggling, repair intermittent short or open circuit. Perform TEST VER-
5A under VERIFICATION TESTS. If OSS reading did not drop, no problem
is indicated at this time.
FTC P1595: SPEED CONTROL SOLENOID CIRCUITS
Speed Control (S/C) solenoid circuits are monitored when
engine is running, S/C switch is on and battery voltage is more than

IDENTIFICATION. For wiring diagram, see WIRING DIAGRAMS.
1) Turn ignition on. Using scan tool, read S/C inputs. While
observing display, press S/C ON/OFF switch several times and leave on.
If scan tool displays S/C switch OFF and ON, go to next step. If scan
tool does not display OFF and ON, go to step 3).
2) Using scan tool, measure S/C switch voltage. While
observing display, wiggle wiring between S/C switch and PCM. If
voltage was more than 4.9 volts at any time during wiggling, repair
wiring as necessary. Perform TEST VER-4A under VERIFICATION TESTS. If
voltage was 4.9 volts or less during wiggling, test is complete.
3) Turn ignition off. Disconnect S/C ON/OFF switch. Inspect
connector. Clean or repair as necessary. Using an ohmmeter, measure
resistance of S/C switch ground circuit. If resistance is 5 ohms or
more, repair open ground circuit. Perform TEST VER-4A under
VERIFICATION TESTS. If resistance is less than 5 ohms, go to next
step.
4) Turn ignition on. Using a voltmeter, measure voltage on
S/C switch signal circuit. If voltage is more than 6 volts, repair
short to voltage. Perform TEST VER-4A under VERIFICATION TESTS. If
voltage is 6 volts or less, go to next step.
5) Turn ignition off. Disconnect PCM. Inspect connectors.
Clean or repair as necessary. Using an ohmmeter, measure resistance of
S/C switch signal circuit between ON/OFF switch connector and PCM
connector C3, terminal No. 32 (White/Light Green wire on Ram Van & Ram
Wagon; Red/Light Green wire on all other models). If resistance is
less than 5 ohms, go to next step. If resistance is 5 ohms or more, go
to step 7).
6) Using an ohmmeter, measure resistance across ON/OFF
switch. Resistance should be 20,300-20,700 ohms. If resistance is not
as specified, replace ON/OFF switch. Perform TEST VER-4A under
VERIFICATION TESTS. If resistance is as specified, replace PCM.
Perform TEST VER-4A under VERIFICATION TESTS.
7) Disconnect clockspring 5-pin connector. Clockspring 5-pin
connector is located behind lower steering column shroud. Inspect
connectors. Clean or repair as necessary. Using an ohmmeter, measure
resistance of S/C switch signal circuit between PCM connector C3,
terminal No. 32 and clockspring connector (White/Light Green wire on
Ram Van and Ram Wagon; Red/Light Green wire on all other models). If
resistance is 5 ohms or more, repair open circuit. Perform TEST VER-4A
under VERIFICATION TESTS. If resistance is less than 5 ohms, replace
clockspring. See appropriate AIR BAG RESTRAINT SYSTEMS article.
Perform TEST VER-4A under VERIFICATION TESTS.
FTC P1597: SPEED CONTROL SWITCH ALWAYS LOW
FTC P1597 will set if Speed Control (S/C) switch voltage is
less than 0.39 volts for 2 minutes when ignition is on and battery
voltage is more than 10.4 volts.
Possible Causes:
* S/C ON/OFF switch defective.
* S/C RESUME/ACCEL switch defective.
* S/C switch signal circuit shorted to ground.
* Defective PCM.
* Defective clockspring.
NOTE: For component locations, see COMPONENT LOCATIONS. For
connector terminal identification, see CONNECTOR
IDENTIFICATION. For wiring diagram, see WIRING DIAGRAMS.
1) Turn ignition on. Using scan tool, read S/C switch

under VERIFICATION TESTS. If voltage is one volt or more, go to next
step.
2) Turn ignition off. Using an ohmmeter, check resistance of
RESUME/ACCEL switch ground circuit at RESUME/ACCEL switch connector.
If resistance is 5 ohms or more, repair open ground circuit. Perform
TEST VER-4A under VERIFICATION TESTS. If resistance is less than 5
ohms, repair open S/C switch signal circuit. Perform TEST VER-4A under
VERIFICATION TESTS.
VERIFICATION TESTS
TEST VER-4A
NOTE: If PCM has been replaced and correct VIN and mileage have not
been programmed, a FTC will be set in ABS and air bag
modules. If vehicle is equipped with a Sentry Key Immobilizer
Module (SKIM), sentry key data must be updated to enable
starting. See COMPUTER RELEARN PROCEDURES article in GENERAL
INFORMATION.
1) If vehicle is not equipped with a diesel engine, go to
next step. If vehicle is equipped with a diesel engine, and PCM has
been disconnected or replaced, battery has been disconnected, or
Accelerator Pedal Position Sensor (APPS) has been disconnected or
replaced, APPS calibration must be programmed into PCM (diesel only).
Turn ignition on. Slowly press accelerator pedal to floor and slowly
release. DO NOT attempt to adjust screws or disassemble APPS. Go to
next step.
2) On all engines, if vehicle is equipped with ABS or air
bag, enter correct VIN and mileage in PCM. Erase DTCs in ABS and air
bag modules. Inspect vehicle to ensure all engine and speed control
system components are connected. Reassemble and reconnect components
as necessary. Using scan tool, erase DTCs from PCM.
3) Road test vehicle at a speed greater than 35 MPH. Turn S/C
switch on. Press and release SET button. If S/C does not engage,
repair is not complete. Check for related TSBs and return to TROUBLE
SHOOTING, if necessary. If speed control engages, go to next step
4) Quickly depress and release RESUME/ACCEL switch. If
vehicle speed increases by 2 MPH, go to next step. If vehicle speed
does not increase by 2 MPH, repair is not complete. Check for related
TSBs and return to TROUBLE SHOOTING, if necessary.
5) Press and hold COAST switch. Vehicle speed should
decrease. If vehicle speed decreases, go to next step. If vehicle
speed does not decrease, repair is not complete. Check for related
TSBs and return to TROUBLE SHOOTING, if necessary.
6) Using caution, depress and release brake pedal. If S/C
disengages, go to next step. If S/C does not disengage, repair is not
complete. Check for related TSBs and return to TROUBLE SHOOTING, if
necessary.
7) Bring vehicle speed to 35 MPH. Depress speed control
RESUME/ACCEL switch. If vehicle resumes to previously set speed, go to
next step. If vehicle does not resume to previously set speed, repair
is not complete. Check for related TSBs and return to TROUBLE
SHOOTING, if necessary.
8) Hold down SET switch. Vehicle speed should decrease. If
vehicle speed decreases, go to next step. If vehicle speed did not
decrease, repair is not complete. Check for related TSBs and return to
TROUBLE SHOOTING, if necessary.
9) Ensure vehicle speed is more than 35 MPH and release SET
switch. If vehicle sets a new speed, go to next step. If vehicle did
not set a new speed, repair is not complete. Check for related TSBs
and return to TROUBLE SHOOTING, if necessary.

10) Depress and release CANCEL switch. If S/C disengages, go
to next step. If S/C did not disengage, repair is not complete. Check
for related TSBs and return to TROUBLE SHOOTING, if necessary.
11) Ensure vehicle speed is greater than 35 MPH. Engage speed
control. Turn S/C on/off switch to OFF position. If speed control
disengages, system is operating correctly. Repair is complete. If
speed control does not disengage, repair is not complete. Check for
related TSBs and return to TROUBLE SHOOTING, if necessary.
TEST VER-5A
NOTE: If PCM has been replaced and correct VIN and mileage have not
been programmed, a FTC will be set in ABS and air bag
modules. If vehicle is equipped with a Sentry Key Immobilizer
Module (SKIM), sentry key data must be updated to enable
starting. See COMPUTER RELEARN PROCEDURES article in GENERAL
INFORMATION.
1) If vehicle is not equipped with a diesel engine, go to
next step. If vehicle is equipped with a diesel engine, and PCM has
been disconnected or replaced, battery has been disconnected, or
Accelerator Pedal Position Sensor (APPS) has been disconnected or
replaced, APPS calibration must be programmed into PCM (diesel only).
Turn ignition on. Slowly press accelerator pedal to floor and slowly
release. DO NOT attempt to adjust screws or disassemble APPS. Go to
next step.
2) On all engines, if vehicle is equipped with ABS or air
bag, enter correct VIN and mileage in PCM. Erase DTCs in ABS and air
bag modules. Inspect vehicle to ensure all engine and speed control
system components are connected.
3) If there are any DTCs that have not been repaired, go to
SELF-DIAGNOSTIC SYSTEM. After all DTCs have been repaired, run
appropriate monitor for previously repaired FTC.
4) Connect scan tool to DLC. Ensure fuel tank is at least 1/4
full. Turn off all accessories. Allow PCM to run appropriate monitor
and increment appropriate good trip. Enabling conditions must be met
before monitor will run.
5) Using scan tool, monitor pretest enabling conditions until
all conditions have been met. Once enabling conditions have been met,
monitor appropriate monitor.
6) If repaired FTC has reset or was seen in monitor while on
road test, repair is not complete. Check for TSBs or flash updates and
return to TROUBLE SHOOTING.
7) If appropriate monitor ran, good trip counter incremented
and no DTCs have been set, repair is complete.
REMOVAL & INSTALLATION
WARNING: Vehicle is equipped with an air bag. Air bag must be
deactivated before servicing speed control components on or
around steering column. See AIR BAG RESTRAINT SYSTEMS -
TRUCKS article.
CAUTION: When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may exist
until computer systems have completed a relearn cycle. See
COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION
before disconnecting battery.
BRAKE SWITCH
Removal

Fully depress brake pedal and rotate brake switch
counterclockwise approximately 30 degrees. Remove brake switch from
bracket. Depress lock tabs holding brake switch mounting bracket and
separate harness connector from brake switch.
Installation
1) Before installing brake switch, reset adjustable plunger
by pulling on plunger head until plunger reaches end of travel.
Connect harness connector to brake switch. Depress brake pedal and
insert brake switch into keyed hole in mounting bracket. Rotate brake
switch clockwise into locked position.
2) Gently pull back on brake pedal until pedal will go no
further. This causes the brake switch plunger to ratchet backward to
the correct position. No further adjustment is required.
SPEED CONTROL SERVO
Removal (Except Ram Van & Ram Wagon)
1) Disconnect negative battery cable. Disconnect electrical
connector and vacuum hose from servo. Using finger pressure only, push
servo cable connector from throttle body bellcrank pin. DO NOT pull
cable connector perpendicular to bellcrank.
2) Remove 2 servo cable mounting nuts. Pull servo cable
sleeve away from mounting bracket to expose cable retaining clip.
Remove retaining clip. Remove servo.
Removal (Ram Van & Ram Wagon)
1) Disconnect negative battery cable. Remove engine cover.
Remove air cleaner assembly. Using finger pressure only, push servo
cable connector from throttle body bellcrank pin. DO NOT pull cable
connector perpendicular to bellcrank.
2) Remove right headlight assembly. Disconnect vacuum hose
and electrical connector at servo. Remove 2 servo mounting bracket
bolts. Remove 2 servo cable mounting nuts. Pull servo cable sleeve
away from mounting bracket to expose cable retaining clip. Remove
retaining clip. Remove servo.
Installation (All Models)
With throttle in full open position, align hole in speed
control cable sleeve with hole in servo pin. Install retaining clip.
To complete installation, reverse removal procedure. Tighten mounting
bolts/nuts to 75 INCH lbs. (8.5 N.m).
SPEED CONTROL SWITCHES
Removal & Installation
Turn ignition off. Disconnect negative battery cable. Wait 2
minutes for air bag system to discharge reserve voltage. Remove 2
screws holding air bag assembly to steering column. Separate air bag
assembly from steering column and disconnect air bag, horn and speed
control switch connectors. Remove screws securing speed control switch
to air bag assembly. Separate speed control switch from air bag
assembly. To install, reverse removal procedure.
WIRING DIAGRAMS

ELE C TR IC AL C O M PO NEN T L O CATO R

1999 D odge P ic ku p R 1500
1999 ELECTRICAL COMPONENT LOCATION
Chrysler Motors Electrical Component Location
Dodge; Ram Pickup
SAFETY PRECAUTION
WARNING: When working on vehicles equipped with Supplemental Restraint
System (SRS), never apply electrical voltage to the system.
This could cause the SRS (air bag) to be deployed.
BUZZERS, RELAYS & TIMERS









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Component Component Location








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A/C Compressor Clutch Relay On power distribution center.
Automatic Shut Down Relay On power distribution center.
Blower Motor Relay On power distribution center.
Central Timer Module Left side of dash, inboard of
steering column opening.
Combination Flasher Left side of dash, on
junction block.
Engine Starter Motor Relay On power distribution center.
Fog Lamp Relay On power distribution center.
Fuel Heater Relay (Diesel) On power distribution center.
Fuel Pump Relay On power distribution center.
Horn Relay On power distribution center.
Intake Air Heater Relay No. 1
(Diesel) On left inner fender, below
left battery.
Intake Air Heater Relay No. 2
(Diesel) On left inner fender, below
left battery.
Quad High Beam Relay On power distribution center.
Radio Choke Relay Behind center of dash, on
support.
Security Relay On power distribution center.
Trailer Tow Relay On power distribution center.
Transmission Control Relay On power distribution center.
Wiper Motor Relay On power distribution center.









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