DODGE RAM 1999 Service Repair Manual

Fig. 1: Locating Powertrain Control Module (PCM)
Courtesy of Chrysler Corp.
ENGINE SENSORS & SWITCHES
SENSORS
Battery Temperature Sensor
1) Battery temperature sensor is snapped into battery tray,
below driver's side battery. Disconnect wiring harness at battery
temperature sensor.
2) Using ohmmeter, check resistance between electrical
terminals on battery temperature sensor. Resistance should be 9000-11,
000 ohms at 75-80
F (25-27C). Replace battery temperature sensor if
resistance is not within specification.
3) If problem exists in battery temperature sensor or wiring
circuit, a Diagnostic Trouble Code (DTC) will be stored in Powertrain
Control Module (PCM). See SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Crankshaft Position Sensor
If problem exists in crankshaft position sensor, a Diagnostic
Trouble Code (DTC) will be stored in Powertrain Control Module (PCM)\
.
See appropriate crankshaft position sensor test in SELF-DIAGNOSTICS -
JEEP, TRUCKS & RWD VANS article.
Fuel Heater Temperature Sensor
See FUEL DELIVERY under FUEL SYSTEM.
Intake Manifold Air Temperature Sensor
Intake manifold air temperature sensor is located on top of
intake manifold, behind intake manifold air heater. For testing, see
DTC P0113: INTAKE AIR TEMPERATURE SENSOR VOLTAGE HIGH test in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Transmission Governor Pressure Sensor (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.
Transmission Speed Sensor (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.
Transmission Temperature Sensor (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.
Water-In-Fuel (WIF) Sensor
Water-in-fuel sensor is located in bottom of fuel
filter/water separator. Testing information not available from
manufacturer.
SWITCHES
Brake Switch
1) Remove lower panel for access to brake switch. Brake
switch is located on bracket, near top of brake pedal. Disconnect
electrical connector from brake switch. Pull plunger on brake switch
fully outward. See Fig. 2.
2) Using ohmmeter, check for continuity between terminals No.
5 and 6 on brake switch. See Fig. 2. Continuity should exist. If
continuity exists, go to next step. If continuity does not exist,
replace brake switch.
3) Push plunger on brake switch fully inward. Using ohmmeter,
check for continuity between terminals No. 1 and 2, and 3 and 4 on
brake switch. See Fig. 2. Continuity should exist. If continuity does
not exist, replace brake switch.
Fig. 2: Identifying Brake Switch Terminals
Courtesy of Chrysler Corp.
Park/Neutral Switch (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Overdrive Switch (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.
RELAYS & SOLENOIDS
RELAYS
A/C Clutch Relay
A/C clutch relay may also be referred to as A/C compressor
clutch relay. A/C clutch relay is located in power distribution center
at driver's side front corner of engine compartment, near battery. If
problem exists in A/C clutch relay or wiring circuit, a Diagnostic
Trouble Code (DTC) will be stored in Powertrain Control Module (PCM)\
.
See DTC P0645 in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Auto Shutdown (ASD) Relay
ASD relay is located in power distribution center at driver's
side front corner of engine compartment, near battery. If problem
exists in ASD relay or wiring circuit, a Diagnostic Trouble Code (DTC)\
will be stored in Powertrain Control Module (PCM). See SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Fuel Heater Relay
1) Fuel heater relay is located in Power Distribution Center
(PDC) next to left battery. Refer to PDC lid for relay location.
Remove relay and note terminal identification on relay. See Fig. 3.
2) Using ohmmeter, check resistance between terminals No. 85
and 86 on relay. Resistance should be 70-80 ohms. If resistance is
within specification, go to next step. If resistance is not within
specification, replace relay.
3) Using ohmmeter, ensure continuity exists between terminals
No. 30 and 87A on relay. If continuity exists, go to next step. If no
continuity exists, replace relay.
4) Using ohmmeter, ensure no continuity exists between
terminals No. 30 and 87 on relay. If no continuity exists, go to next
step. If continuity exists, replace relay.
5) Using jumper wires, connect terminal No. 85 to negative
side of 12-volt power source and terminal No. 86 to positive side of
12-volt power source. Using ohmmeter, ensure no continuity now exists
between terminals No. 30 and 87A on relay. If no continuity exists, go
to next step. If continuity exists, replace relay.
CAUTION: DO NOT allow ohmmeter leads to contact terminals No. 85 and
86 on relay when checking resistance.
6) Using ohmmeter, ensure continuity now exists between
terminals No. 30 and 87 on relay. If continuity exists, disconnect
jumper wires from relay. If no continuity exists, replace relay.
NOTE: For additional information on checking wiring circuit for
fuel heater relay, see TEST NTC-1: NO TROUBLE CODE TEST MENU
and TEST NS-SEL: NO START TEST SELECTION in SELF-DIAGNOSTICS
- JEEP, TRUCKS & RWD VANS article.

Fig. 3: Fuel Heater Relay Terminals
Courtesy of Chrysler Corp.
Intake Manifold Air Heater Relays
1) Intake manifold air heater relays may also be referred to
as intake air heater relays. Intake manifold air heater relays are
mounted on inner wheelwell, below driver's side battery. See Fig. 4.
2) Disconnect negative battery cables. Note location of
wiring on intake manifold air heater relays for reassembly reference.
Disconnect all electrical connectors and cables from intake manifold
air heater relays.
3) Connect ohmmeter between large terminals on intake
manifold air heater relay to check for continuity. Using jumper wires,
momentarily apply battery voltage to relay trigger wire terminals
(small wire terminals) at base of intake manifold air heater relay.
See Fig. 4 . Polarity is not important.
4) Intake manifold air heater relay should click and ohmmeter
should indicate continuity between large terminals when battery
voltage is applied to relay trigger wire terminals. If intake manifold
air heater relay operation is not as specified, replace intake
manifold air heater relay with bracket. Test remaining intake manifold
air heater relay. Remove ohmmeter. Reconnect all electrical connectors
and negative battery cables.
NOTE: For additional information on checking wiring circuit for
intake manifold air heater relay, see DTC P0380: INTAKE AIR
HEATER RELAY NO. 1 CONTROL CIRCUIT and DTC P0382: INTAKE AIR
HEATER RELAY NO. 2 CONTROL CIRCUIT tests in SELF-DIAGNOSTICS
- JEEP, TRUCKS & RWD VANS article.

Fig. 4: Locating Intake Manifold Air Heater Relays
Courtesy of Chrysler Corp.
Transmission Relay (A/T Models)
Transmission relay may be referred to as transmission control
relay or transmission 12-volt supply relay. Transmission relay is
located in power distribution center at driver's side front corner of
engine compartment, near battery. If problem exists in transmission
relay or wiring circuit, a Diagnostic Trouble Code (DTC) will be
stored in Powertrain Control Module (PCM). See DTC P1765: TRANSMISSION\
12-VOLT SUPPLY RELAY CONTROL CIRCUIT test in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
SOLENOIDS
Transmission Overdrive Solenoid (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Torque Converter Clutch Solenoid (A/T Models)
See TRANSMISSION under MISCELLANEOUS CONTROLS.
Fig. 5: Locating Fuel System Components
Courtesy of Chrysler Corp.
FUEL SYSTEM

FUEL DELIVERY
Fuel Filter/Water Separator
1) A restricted fuel filter/water separator may cause engine
starting problems, prevent engine from accelerating, low power or
White exhaust smoke.
2) When ignition is first turned on, WATER-IN-FUEL (WIF)
warning light should come on for 2 seconds to perform bulb and wiring
circuit test and then go off. WATER-IN-FUEL (WIF) warning light is
located on instrument panel, just below tachometer.
3) If WATER-IN-FUEL (WIF) warning light stays on, water
should be drained from fuel filter/water separator. To drain water
from fuel filter/water separator, ensure engine is not running. Place
drain pan below drain tube at fuel filter/water separator.
4) Rotate handle on drain valve forward, toward front of
vehicle to DRAIN position. Drain valve is located near top of fuel
filter/water separator.
5) If no water exists and a clean flow of diesel fuel exists,
rotate handle on drain valve back to CLOSE position. Go to next step.
If water exists, allow water to drain until clean flow of diesel fuel
exists. Rotate handle on drain valve back to CLOSE position. Go to
next step.
6) Verify fuel filter/water separator has been serviced
according to proper service schedule. See SERVICE & ADJUSTMENT
SPECIFICATIONS - TRUCKS article. Ensure pre-filter was cleaned when
fuel filter/water separator was serviced. Pre-filter is located at
bottom of fuel heater on driver's side of engine. No other testing
information is available from manufacturer.
Fuel Heater
1) Malfunctioning fuel heater may cause excessive wax build-
up in fuel filter/water separator during cold ambient temperatures.
Wax build-up may cause hard starting, prevent engine from
accelerating, low power, or Blue or White smoke.
2) Disconnect electrical connector at fuel heater. Fuel
heater is located in top of fuel filter housing. Using ohmmeter, check
resistance between electrical terminals on fuel heater.
3) Resistance should be about one ohm when fuel is cold, and
about 1000 ohms when fuel is warm. Replace fuel heater if resistance
is not within specification.
NOTE: Fuel heater receives battery voltage from fuel heater relay.
Fuel heater relay is located in Power Distribution Center
(PDC), next to left battery. Refer to PDC lid for relay
location. For testing of fuel heater relay, see RELAYS under
RELAYS & SOLENOIDS. Consult wiring diagram for wiring circuit
testing. See appropriate wiring diagram in WIRING DIAGRAMS
article.
Fuel Transfer Pump Preliminary Inspection
1) Check for restricted or leaking fuel supply line to fuel
transfer pump or fuel return line located on driver's side of engine.
Repair fuel supply line or fuel return line if restricted or leaking.
2) Check for fuel leaking from weep hole on housing of fuel
transfer pump. Replace fuel transfer pump if fuel is leaking from weep
hole. Check fuel transfer pump for output pressure, pressure drop,
supply restriction, and air leaks.
NOTE: Separate pressure tests are necessary because transfer pump
operates at 2 pressure cycles, depending on whether engine is
running or cranking.

Fuel Transfer Pump Output Pressure
1) Remove 2 existing filter plug fittings at top of fuel
filter housing. Install 2 spring-loaded one-way check valve fittings
at inlet and outlet port. Install Fuel Pressure Test Gauge (6828) to
inlet port fitting. Prevent engine from starting by removing fuel
injection pump relay. Relay is located in Power Distribution Center
(PDC) next to left battery. Relay location is notated on PDC lid.
2) Crank engine while observing fuel pressure test gauge.
Fuel pressure should be 5-7 psi (0.35-0.49 kg/cm

). Reinstall fuel
system relay to PDC. Start engine. Fuel pressure should be minimum of
10 psi (0.7 kg/cm

). Because fuel injection pump relay was removed, a
Diagnostic Trouble Code (DTC) may have been set. Use DRB scan tool to
erase DTC. Go to PRESSURE DROP test.
Pressure Drop
Turn engine off. Remove Fuel Pressure Test Gauge (6828) from
inlet port and attach to outlet port. Start engine and note fuel
pressure. Pressure should not be more than 5 psi (0.35 kg/cm

) less
than inlet port pressure in Fuel Transfer Pump Outlet Pressure test.
See FUEL TRANSFER PUMP OUTPUT PRESSURE test. If fuel pressure is not
to specification, replace fuel filter. Go to FUEL SUPPLY RESTRICTION
test.
NOTE: Following test requires use of DRB scan tool and Periphal
Expansion Port (PEP) module. Ensure transfer pump pressure is\
okay before performing following test.
Fuel Supply Restriction
1) Disconnect fuel supply line quick-connect fitting at left
rear side of engine compartment. After disconnecting fuel line,
plastic clip will remain attached to metal fuel line at engine. Remove
clip from metal line. Snap clip into fuel supply hose. Install Rubber
Adapter Hose (6631) into ends of disconnected fuel supply line.
2) Install transducer from PEP module to brass "T" fitting on
rubber adapter hose. Connect DRB scan tool to transducer. Start engine
and record vacuum reading with engine speed at wide open throttle.
3) If vacuum reading is less than 6 in. Hg, check for
restriction in fuel supply line or fuel tank module. Repair fuel
supply line or module for restrictions as necessary. Also check fuel
pump inlet filter at bottom of module for obstructions. Go to AIR LEAK
IN FUEL SUPPLY LINE test.
NOTE: Following test requires use of a 3-foot section of 1/4" I.D.
clear tubing and 1/8" fitting.
Air Leak In Fuel Supply Line
1) Locate 2 test port plug fittings at top of fuel filter
housing. Clean fitting area. Remove test port fitting at fuel inlet
side of housing toward rear of filter housing. Install 1/8" fitting
with 1/4" O.D. nipple in place of test port. Clamp clear tubing to
fitting nipple. Place other end of hose into clear container.
2) To put fuel transfer pump into a 25 second run mode, turn
ignition switch to CRANK position, then release back to RUN position
without starting engine. Wait for air to purge from empty hose before
checking whether air bubbles are present. If bubbles are present,
check for leaks in supply line to fuel tank. If supply line is not
leaking, remove fuel tank module. Remove filter at bottom of module.
Check for leaks between supply nipple at top of module and filter
opening at bottom of module. Replace module as necessary.
Overflow Valve
1) Clean area around overflow valve and fuel return line at
injection pump. Remove overflow valve from pump and banjo fitting.

Remove and discard gaskets. Using blow gun with regulated pressure of
about 14-16 psi (0.9-1.1 kg/cm
), apply pressure to overflow valve
inlet end (injection pump side). If internal check valve releases and
air passes through valve, go to next step. If internal check valve
does not release and air does not pass through valve, replace valve.
2) Reduce air pressure to 10 psi (0.7 kg/cm

) and recheck
valve. If valve stays closed, valve is okay. If valve does not stay
closed, replace valve and gaskets.
Fuel Injection Pump
1) Ensure fuel transfer pump output pressure is within
specification before condemning fuel injection pump. See FUEL TRANSFER
PUMP OUTPUT PRESSURE. No mechanical adjustments are needed for fuel
injection timing. All timing and fuel adjustments are made by Engine
Control Module (ECM). If a DTC has been stored indicating an ENGINE
SYNC ERROR or STATIC TIMING ERROR, remove plastic access cover,
injection pump nut and washer.
2) Locate keyway behind washer. Ensure keyway aligning fuel
injection pump shaft to injection pump gear is in correct position and
pump gear has not slipped on pump shaft. Remove timing gear cover to
access timing gears. See 5.9L (24-VALVE) 6-CYLINDER DIESEL article in
ENGINES section. Use a "T" puller and separate injection pump gear
from pump shaft. Ensure keyway is installed with arrow toward rear of
pump.
NOTE: Pump timing is calibrated to pump keyway. Ensure 3-digit
number on pump keyway matches 3-digit number on fuel
injection pump data plate on side of injection pump.
See Fig. 6.
3) Ensure timing marks on crank, camshaft and pump align.
Align gears as necessary. After repair, erase DTC.
Fig. 6: Locating Fuel System Components
Courtesy of Chrysler Corp.
FUEL CONTROL

NOTE: A leaking fuel injector or high-pressure fuel line may cause
a rough idle, Black smoke, poor engine performance, poor fuel
economy and fuel knock. Following procedure is for
determining if fuel injector is defective.
WARNING: DO NOT allow diesel fuel to contact hot engine when checking
fuel injector, as high exhaust temperatures could cause a
fire. Use care when working around high-pressure fuel lines,
as fuel is under extreme pressure and could penetrate skin,
causing personal injury. Wear safety goggles and protective
clothing when checking fuel injectors.
Fuel Injector
1) Since a leaking high-pressure fuel line may cause the same
symptoms, check for leaking high-pressure fuel line before checking
fuel injector. To check for a leaking high-pressure fuel line, start
engine and allow engine to idle.
2) Inspect high-pressure fuel lines and connections for signs
of fuel leakage by placing cardboard over high-pressure fuel line and
connection. Note if leak is being detected by fuel being sprayed onto
cardboard. If leak exists, repair leak by tightening high-pressure
fuel line nut to 18 ft. lbs. (24 N.m) or replacing high-pressure fuel
line as necessary. If high-pressure fuel line is replaced, bleed air
from fuel system. See FUEL LINE BLEEDING under FUEL SYSTEM in REMOVAL,
OVERHAUL & INSTALLATION article.
3) To check for defective fuel injector, start and idle
engine. Loosen high-pressure fuel line nut at fuel injector and listen
for a decrease in engine speed. Tighten high-pressure fuel line nut to
18 ft. lbs. (24 N.m).
4) If fuel injector is operating properly, engine idle speed
should decrease when high-pressure fuel line nut is loosened. Repeat
procedure on each fuel injector.
5) If engine idle speed does not decrease, fuel injector is
defective and should be removed and tested with a diesel fuel injector
tester. Replace fuel injector if fuel injector opening (pop) pressure
is not about 4500 psi (316 kg/cm

).
EMISSION SYSTEMS & SUB-SYSTEMS
INTAKE MANIFOLD AIR HEATER SYSTEM
Intake Manifold Air Heater Preheat/Postheat Cycle
For testing information on intake manifold air heater system,
see DTC P0380: INTAKE AIR HEATER RELAY NO. 1 CONTROL CIRCUIT and DTC
P0382: INTAKE AIR HEATER RELAY NO. 2 CONTROL CIRCUIT tests in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
MISCELLANEOUS CONTROLS
NOTE: Although some controlled devices listed here are not
technically engine performance components, they can affect
driveability if they malfunction.
TRANSMISSION
Park/Neutral Switch (A/T Models)
Park/neutral switch is mounted on transmission case, near
shift lever and contains a 3-pin connector. If problem exists in
park/neutral switch or wiring circuit, a Diagnostic Trouble Code (DTC)\
will be stored in Powertrain Control Module (PCM). See DTC P1899: P/N
SWITCH STUCK IN PARK OR IN GEAR test in SELF-DIAGNOSTICS - JEEP,