1999 DODGE RAM Service Repair Manual

Intake Air Temperature (IAT) Sensor
See appropriate DTC P0112: IAT SENSOR VOLTAGE LOW and DTC
P0113: IAT SENSOR VOLTAGE HIGH tests in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Manifold Absolute Pressure (MAP) Sensor
See appropriate DTC P0107: MAP SENSOR VOLTAGE TOO LOW and DTC
P0108: MAP SENSOR VOLTAGE TOO HIGH tests in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Transmission Temperature (TRANS Temp) Sensor
See appropriate DTC P0711: TRANSMISSION TEMPERATURE SENSOR,
NO TEMPERATURE RISE AFTER START, DTC P0712: TRANSMISSION TEMPERATURE
SENSOR VOLTAGE TOO LOW, and DTC P0713: TRANSMISSION TEMPERATURE SENSOR
VOLTAGE TOO HIGH tests in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Throttle Position (TP) Sensor
See appropriate DTC P0122: THROTTLE POSITION SENSOR VOLTAGE
LOW and DTC P0123: THROTTLE POSITION SENSOR VOLTAGE HIGH tests in
SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Vehicle Speed Sensor (VSS)
See appropriate DTC P0500: NO VEHICLE SPEED SENSOR SIGNAL
test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
SOLENOIDS
Evaporative (EVAP) Purge Solenoid
See appropriate DTC P0443: EVAP PURGE SOLENOID CIRCUIT test
in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Leak Detection Pump (LDP) Solenoid
See appropriate DTC P1495: LEAK DETECTION PUMP SOLENOID
CIRCUIT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Speed Control (S/C) Solenoid
See appropriate DTC P1595: SPEED CONTROL SOLENOID CIRCUITS
test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Transmission Governor Pressure Solenoid
See appropriate DTC P0748: GOVERNOR PRESSURE
SOLENOID/TRANSMISSION RELAY CIRCUITS test in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Transmission 3-4 Solenoid
See appropriate DTC P0783: TRANSMISSION 3-4 SHIFT SOLENOID,
NO RPM DROP AT 3-4 SHIFT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD
VANS article.
SWITCHES
Leak Detection Pump (LDP) Switch
See appropriate DTC P1494: LEAK DETECTION PUMP SWITCH OR
MECHANICAL FAULT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Park/Neutral (P/N) Switch
See appropriate DTC P1899: PARK/NEUTRAL SWITCH STUCK IN PARK
OR IN GEAR test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Power Steering (PS) Switch
See appropriate DTC P0551: POWER STEERING SWITCH FAILURE test

in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Speed Control Switch
See appropriate DTC P1596: SPEED CONTROL SWITCH ALWAYS HIGH
and DTC P1597: SPEED CONTROL SWITCH ALWAYS LOW tests in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
RELAYS
A/C Clutch Relay
See appropriate DTC P0645: A/C CLUTCH RELAY CIRCUIT test in
SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Auto Shutdown (ASD) Relay
See appropriate DTC P1388: AUTO SHUTDOWN RELAY CONTROL
CIRCUIT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Fuel Pump Relay
See appropriate DTC P1282: FUEL PUMP RELAY CONTROL CIRCUIT
test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Radiator Fan Control Relay
See appropriate DTC P1491: RADIATOR FAN CONTROL RELAY CIRCUIT
test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
Torque Converter Clutch (TCC) Relay
See appropriate DTC P0743: TORQUE CONVERTER CLUTCH
SOLENOID/TRANSMISSION RELAY CIRCUIT test in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Transmission Governor Pressure Solenoid Relay
See appropriate DTC P0748: GOVERNOR PRESSURE
SOLENOID/TRANSMISSION RELAY CIRCUIT test in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Transmission 12-Volt Supply Relay
See appropriate DTC P1765: TRANSMISSION 12-VOLT SUPPLY RELAY
CONTROL CIRCUIT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Vehicle Speed Control Relay
See appropriate DTC P1683: SPEED CONTROL POWER RELAY CIRCUIT
test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
FUEL SYSTEM
FUEL DELIVERY
NOTE: For fuel system pressure testing, see BASIC DIAGNOSTIC
PROCEDURES - TRUCKS & RWD VANS - GASOLINE article.
FUEL CONTROL
Fuel Injector
See appropriate injector control circuit test in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
IDLE CONTROL SYSTEM
IDLE AIR CONTROL (IAC) MOTOR

See appropriate DTC P0505: IAC MOTOR CIRCUIT in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
IGNITION SYSTEM
NOTE: For basic ignition checks, see TEST NS-SEL: NO START TEST
SELECTION in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
EMISSION SYSTEMS & SUB-SYSTEMS
NOTE: To locate emission components, refer to emission control
information label in engine compartment.
AIR INJECTION
No Air Supply (Ram Pickup 5.9L & 8.0L)
1) Start engine, and increase engine speed to 1500 RPM. Check
air supply at rubber hoses. If air supply increases with RPM, air pump
operation is okay.
2) If air pump is okay, check for leakage at hoses and
fittings. Repair or replace hoses as necessary.
3) If hoses are okay, check pressure relief valve for
leakage. If air is expelled through pressure relief valve at idle,
replace relief valve.
4) If relief valve is okay on 5.9L, test is complete. On 8.
0L, check inlet air filter. Repair air filter if plugged. If air
filter is okay, test is complete.
CRANKCASE VENTILATION (CCV)
8.0L
1) CCV system does NOT use a PCV valve. System consists of a
fixed orifice (Gray color) that is calibrated to a specific flow rate.\
The fixed orifice (located on intake manifold) is connected by a tube
to right valve cover.
2) A similar orifice is used on left cylinder head, but is
Black in color and cannot be interchanged with Gray orifice. Ensure
orifice, tubes and fittings are clean and in good condition. No
further information is available from manufacturer.
EXHAUST GAS RECIRCULATION (EGR)
EGR Valve
See TEST NTC-2: CHECKING EGR SYSTEM in SELF-DIAGNOSTICS -
JEEP, TRUCKS & RWD VANS article.
FUEL EVAPORATION
EVAP Canister
EVAP canister is located in engine compartment. Canister has
no moving parts. Check for loose, missing, cracked or broken
connections and parts. Repair or replace as necessary. No liquid
should be in canister.
LEAK DETECTION PUMP (LDP)
LDP
See appropriate DTC P1494: LEAK DETECTION PUMP SWITCH OR
MECHANICAL FAULT test in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS

article.
POSITIVE CRANKCASE VENTILATION (PCV)
PCV Valve
1) With engine running at curb idle, remove PCV valve from
grommet. If valve is functioning properly, a hissing sound will be
heard as air passes through valve.
2) With engine running, place finger over valve inlet. Strong
vacuum should be felt at valve inlet. Stop engine. Remove and shake
PCV valve to ensure a metallic clicking noise can be heard, indicating
valve is free. Reinstall PCV valve.
3) Remove crankcase ventilation filter or oil filler cap from
valve cover. Hold a piece of stiff paper over opening. After allowing
about one minute for crankcase pressure stabilization, paper should be
drawn against opening.
4) If paper is held against opening, performance is okay. If
paper is not held against opening, replace PCV valve and retest. If
performance does not improve, inspect system for restrictions and
clean as necessary.
MISCELLANEOUS CONTROLS
NOTE: Although the controlled devices listed here are not
technically engine performance components, they can affect
driveability if they malfunction.
RELAYS
A/C Clutch Relay
See A/C CLUTCH RELAY under RELAYS.
Radiator Fan Control Relay
See RADIATOR FAN CONTROL RELAY under RELAYS.
Torque Converter Clutch (TCC) Relay
See TORQUE CONVERTER CLUTCH (TCC) RELAY under RELAYS
Transmission Governor Pressure Solenoid Relay
See TRANSMISSION GOVERNOR PRESSURE SOLENOID RELAY under
RELAYS.
Transmission 12-Volt Supply Relay
See TRANSMISSION 12-VOLT SUPPLY RELAY under RELAYS.
Vehicle Speed Control Relay
See VEHICLE SPEED CONTROL RELAY under RELAYS.

SYSTE M W IR IN G D IA G RAM S

1999 D odge P ic ku p R 1500
1999 System Wiring Diagrams
Dodge - Pickup R1500
AIR CONDITIONING
Heater Circuit

Manual A/C Circuit
ANTI-LOCK BRAKES

Anti-lock Brake Circuits
ANTI-THEFT

Anti-theft Circuit
BODY COMPUTER