Engine Controls - System & Component Testing - Cng: Other

Engine Controls - System & Component Testing - Cng: Other Dodge Ram Wagon B1500

POWERTRAIN CONTROL MODULE (PCM)

The PCM power and ground circuits may be checked by performing TEST NTC-14 in SELF-DIAGNOSTICS - RWD VANS article. PCM is located on firewall, near wiper motor.

A/C Clutch Relay

See DTC P0645: A/C CLUTCH RELAY CIRCUIT in SELF-DIAGNOSTICS - RWD VANS article.

Auto Shutdown (ASD) Relay

See DTC P1388: ASD RELAY CONTROL CIRCUIT and DTC P1388: NO ASD RELAY OUTPUT VOLTAGE AT PCM in SELF-DIAGNOSTICS - RWD VANS article.

Radiator Fan Control Relay

See DTC P1491: RADIATOR FAN CONTROL RELAY CIRCUIT in SELF-DIAGNOSTICS - RWD VANS article.

Transmission Governor Pressure Solenoid Relay

See DTC P0748: GOVERNOR PRESSURE SOLENOID/TRANS RELAY CKTS in SELF-DIAGNOSTICS - RWD VANS article.

Transmission 12-Volt Supply Relay

See DTC P1765: TRANS 12 VOLT SUPPLY RELAY CONTROL CIRCUIT in SELF-DIAGNOSTICS - RWD VANS article.

Vehicle Speed Control Relay

See DTC P1683: SPEED CONTROL POWER RELAY CIRCUIT in SELF-DIAGNOSTICS - RWD VANS article.

Camshaft Position (CMP) Sensor

See DTC P0340: NO CAM SIGNAL AT TACH and DTC 1391: INTERMITTENT LOSS OF CKP OR CMP in SELF-DIAGNOSTICS - RWD VANS article.

Crankshaft Position (CKP) Sensor

See DTC P0320: NO CRANK REFERENCE SIGNAL AT PCM and DTC 1391: INTERMITTENT LOSS OF CKP OR CMP in SELF-DIAGNOSTICS - RWD VANS article.

Engine Coolant Temperature (ECT) Sensor

See DTC P0117: ECT SENSOR VOLTAGE TOO LOW and DTC P0118: ECT SENSOR VOLTAGE TOO HIGH in SELF-DIAGNOSTICS - RWD VANS article.

Heated Oxygen Sensor (HO2S)

See appropriate HO2S test procedures in SELF-DIAGNOSTICS - RWD VANS article.

Intake Air Temperature (IAT) Sensor

See DTC P0112: IAT SENSOR VOLTAGE LOW and DTC P0113: IAT SENSOR VOLTAGE HIGH in SELF-DIAGNOSTICS - RWD VANS article.

Manifold Absolute Pressure (MAP) Sensor

See DTC P0107: MAP SENSOR VOLTAGE TOO LOW, DTC P0108: MAP SENSOR VOLTAGE TOO HIGH, DTC P1296: NO 5 VOLTS TO MAP SENSOR, DTC P1297: NO CHANGE IN MAP FROM START TO RUN and TEST NTC-10 in SELF-DIAGNOSTICS - RWD VANS article.

Transmission Temperature (TRANS Temp) Sensor

See DTC P0711: TRANS TEMP SENSOR, NO TEMP RISE AFTER START, DTC P0712: TRANS TEMP SENSOR VOLTAGE TOO LOW and DTC P0713: TRANS TEMP SENSOR VOLTAGE TOO HIGH in SELF-DIAGNOSTICS - RWD VANS article.

Throttle Position (TP) Sensor

See DTC P0122: THROTTLE POSITION SENSOR VOLTAGE LOW, DTC P0123: THROTTLE POSITION SENSOR VOLTAGE HIGH and TEST NTC-17 in SELF-DIAGNOSTICS - RWD VANS article.

Vehicle Speed Sensor (VSS)

See DTC P0500: NO VEHICLE SPEED SENSOR SIGNAL in SELF-DIAGNOSTICS - RWD VANS article.

Speed Control (S/C) Solenoid

See DTC P1595: SPEED CONTROL SOLENOID CIRCUITS in SELF-DIAGNOSTICS - RWD VANS article.

Transmission Governor Pressure Solenoid

See DTC P1763: GOVERNOR PRESSURE SENSOR VOLTS TOO HIGH and DTC P1764: GOVERNOR PRESSURE SENSOR VOLTS TOO LOW in SELF-DIAGNOSTICS - RWD VANS article.

Transmission 3-4 Solenoid

See DTC P0753: TRANS 3-4 SOLENOID/TRANS RELAY CKTS and DTC P0783: TRANS 3-4 SHIFT SOL, NO RPM DROP @ 3-4 SHIFT in SELF-DIAGNOSTICS - RWD VANS article.

Park/Neutral (P/N) Switch

See DTC P1899: P/N SWITCH STUCK IN PARK OR IN GEAR and TEST NTC-13 in SELF-DIAGNOSTICS - RWD VANS article.

Speed Control Switch

See DTC P1596: SPEED CONTROL SWITCH ALWAYS HIGH and DTC P1597: SPEED CONTROL SWITCH ALWAYS LOW in SELF-DIAGNOSTICS - RWD VANS article.

FUEL SYSTEM

Note. For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES - CNG article.

FUEL PRESSURE RELEASE

WARNING

Fuel system is under high pressure. ALWAYS release fuel pressure before attempting to open system for testing or component replacement. System must be purged before removing or replacing components.

Fuel Tube Purging With Engine Running

Note. Use this procedure if engine runs and fuel cylinders are not being serviced.

Close all 4 fuel control valves on cylinders. Open manual master fuel shut-off valve, located between two side cylinders. Start engine and run until engine dies. Attempt to start engine 3 more times. Fuel system is now purged. If one way check valve or fuel fill receptacle is serviced, high pressure will remain in line. Slowly open fitting to relieve residual pressure while outdoors. Fuel cylinders still contain high pressure. After repairs, ensure high pressure fittings are checked with a go no-go gauge. Do not open fuel control valves until all high pressure components have been resealed.

Fuel Tube Purging Without Engine Running

Note. Use this procedure if engine does not run and fuel cylinders are not being serviced.

Close all 4 fuel control valves on cylinders. Open manual master fuel shut-off valve, located between two side cylinders. Move vehicle outdoors. Remove shield mounted below cylinders on left side of vehicle. Cycle ignition switch to ON position a few times to activate high pressure solenoid. Turn ignition off. Slowly loosen fuel line at low pressure fuel shut-off solenoid. Fuel pressure will bleed out. Leave line loosened until all pressure is released. System is now purged. If one way check valve or fuel fill receptacle is serviced, high pressure will remain in line. Slowly open fitting to relieve residual pressure while outdoors. Fuel cylinders still contain high pressure. After repairs, ensure high pressure fittings are checked with a go no-go gauge. Do not open fuel control valves until all high pressure components have been resealed.

Fuel Cylinder Purging With Engine Running

Note. Use this procedure if engine runs and a fuel cylinder is being serviced.

Open manual master fuel shut-off valve. Open fuel control valve on cylinder to be serviced. Close fuel control valves on all cylinders not being serviced. Start engine and run until engine dies. Attempt to start engine 3 more times. Fuel system is now purged. Cylinder may be removed for service. After repairs, ensure high pressure fittings are checked with a go no-go gauge. Do not open fuel control valves until all high pressure components have been resealed.

Fuel Cylinder Purging Without Engine Running

Note. Use this procedure if engine does not run and a fuel cylinder is being serviced.

Open manual master fuel shut-off valve. Open fuel control valve on cylinder to be serviced. Close fuel control valves on all cylinders not being serviced. Very slowly loosen fuel fitting at control valve of fuel cylinder being serviced. High pressure will be released. Leave line loosened until all pressure is released. Fuel cylinder is now purged. Cylinder may be removed for service. After repairs, ensure high pressure fittings are checked with a go no-go gauge. Do not open fuel control valves until all high pressure components have been resealed.

FUEL CYLINDER

Each CNG fuel cylinder manufactured on or after March 27, 1995 must be removed and reinspected after a vehicle accident or fire and at least every 36 months or 36,000 miles, whichever comes first.
Inspection should be performed in accordance with motor vehicle safety standard No. 304 compressed natural gas fuel containers and Compressed Gas Association (CGA), Arlington , Va. Guidelines C-6.4.
Retest markings must be stamped on cylinder neck or marked on a label securely affixed to cylinder and overcoated with epoxy near original test date.
Reheat treatment or repair of rejected cylinders is not authorized.
Fuel cylinder expires and must be removed from service 15 years from date of manufacture. Label on fuel filler door states cylinder expiration date. Each fuel cylinder is also dated. Any questions should be addressed to manufacturer identified on label.

FUEL INJECTORS

Note. Because there is no liquid (gasoline) inside injector to muffle sound, injector may seem louder.

To check fuel injectors and circuits, use scan tool. To check injector only, disconnect electrical connector. Using a set of fused jumper wires, momentarily apply 12 volts across injector terminals. Injector should click. Remove jumper wires. Using an ohmmeter, check resistance between injector terminals. Resistance should be 4-5 ohms. If injector does not operate as specified, replace injector.

LOW FUEL PRESSURE SENSOR

To check low fuel pressure sensor and circuit, use scan tool. To check sensor only, turn ignition on. Check voltage (backprobe) at sensor 3-pin connector terminal "C" (Dark Green/Orange wire). Sensor is located on fuel rail. Voltage should range from .5 volt at 0 psi to 4.5 volts at 250 psi. If zero volts exists, circuit is shorted. If 5 volts exists, circuit is open. Repair wiring or replace sensor if voltage is not correct for measured pressure.

FUEL TEMPERATURE SENSOR

To check fuel temperature sensor and circuit, use scan tool. To check sensor only, disconnect harness connector. Using an ohmmeter, check resistance of sensor. See FUEL TEMPERATURE SENSOR RESISTANCE . If sensor resistance is not as specified, replace sensor.

Temperature F° (C°)	Resistance (Ohms)
40 (-40)	291,490-381,710
4 (-20)	85,850-108,390
14 (-10)	49,250-61,430
32 (0)	29,330-35,990
50 (10)	17,990-21,810
68 (20)	11,370-13,610
77 (25)	9120-10,880
86 (30)	7370-8750
104 (40)	4900-5750
122 (50)	3330-3880
140 (60)	2310-2670
158 (70)	1630-1870
176 (80)	1170-1340
194 (90)	860-970
212 (100)	640-720
230 (110)	480-540
248 (120)	370-410

FUEL TEMPERATURE SENSOR RESISTANCE

HIGH PRESSURE SHUT-OFF SOLENOID

To check high pressure shut-off solenoid and circuit, use scan tool. To check solenoid only, purge fuel system. See FUEL PRESSURE RELEASE . Loosen allen screw in side of manual fuel shut-off valve handle. Remove handle. Remove fuel cylinder shield. Disconnect solenoid pigtail 2-pin harness connector from main harness. Using jumper wires, momentarily apply 12 volts to solenoid harness terminals. Solenoid should click. Replace solenoid if it does not click.

LOW PRESSURE SHUT-OFF SOLENOID

Low pressure shut-off solenoid is located on fuel rail. Disconnect solenoid 2-pin harness connector. Using jumper wires, momentarily apply 12 volts to solenoid terminals. Solenoid should click. Replace solenoid if it does not click.

IDLE AIR CONTROL (IAC) MOTOR

See DTC P0505: IAC MOTOR CIRCUIT and TEST NTC-8 in SELF-DIAGNOSTICS - RWD VANS article.

IGNITION SYSTEM

Note. For secondary ignition checks, see TEST NTC-15 in SELF-DIAGNOSTICS - RWD VANS article.

EMISSION SYSTEMS & SUB-SYSTEMS

Note. To locate emission components, refer to emission control information label in engine compartment.

PCV Valve

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.
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.
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.
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.