Engine Controls - System/component Tests - 5.2l Cng Dodge Ram Wagon B3500

INTRODUCTION

Note. Testing procedures not covered in this article require a Chrysler Diagnostic Readout Box (DRB). See TESTS W/CODES - 5.2L CNG article in the ENGINE PERFORMANCE section.

Note. For component location, see THEORY/OPERATION - 5.2L CNG article in the ENGINE PERFORMANCE section.

Before testing individual components or systems, perform procedures in BASIC TESTING - 5.2L CNG article in the ENGINE PERFORMANCE section. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES - 5.2L CNG article in the ENGINE PERFORMANCE section.

Note. Testing of individual components does not isolate possible shorts or opens in the wiring harness of electronically controlled systems. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in procedure. Use an ohmmeter to isolate wiring harness shorts or opens.

The following engine components (as used on CNG vehicle) are identical to components used on gasoline equipped vehicles. For component testing, see SYSTEM/COMPONENT TESTS - 5.2L CNG section.

1. Throttle Body
2. Accelerator Linkage
3. Manifold Absolute Pressure (MAP) Sensor
4. Engine Coolant Temperature Sensor
5. Intake Manifold
6. Intake Manifold Charge Air Temperature Sensor (5.2L)
7. Throttle Position Sensor
8. Idle Air Control Motor (Automatic Idle Speed)
9. Crankshaft Position Sensor
10. Automatic Shutdown Relay
11. Oxygen Sensor
12. Vehicle Speed Sensor
13. Ignition System
14. Air Conditioning Components
15. Speed Control Components
16. Overdrive Components
17. Alternator (Generator)
18. Park/Neutral Position Switch
19. Brake Switch Controls

Diagnostic Check

PCM is tested using DRB. See appropriate testing in TESTS W/CODES - 5.2L CNG article in the ENGINE PERFORMANCE section.

FUEL PRESSURE SENSOR

With ignition on, backprobe Dark Green/Orange wire at fuel pressure sensor connector. Sensor operating range should be .5-4.5 volts (0-150 psi). If voltage is not within specification, replace sensor and retest.

FUEL TEMPERATURE SENSOR

Sensor is mounted in fuel injector rail. With key off, disconnect wire connector from sensor. Connect ohmmeter between sensor terminals. If ohmmeter readings are not within specification, replace sensor. See TEMPERATURE SENSOR RESISTANCE table.

TEMPERATURE SENSOR RESISTANCE

RELAYS

Note. ASD relay is located in engine compartment, on left side of bulkhead. The high pressure shutoff relay is located to the left of ASD relay.

Auto Shutdown (ASD) & High Pressure Shutoff Relays

1. Relays must be disconnected for testing. Remove relay. Relay terminal numbers are stamped on bottom of relay. (Scheme 134) If any of following resistance and continuity tests fail, replace relay.
2. Using an ohmmeter, measure resistance between terminals No. 85 and 86. Resistance should be 70-80 ohms. Connect ohmmeter between terminals No. 87A and 30. Continuity should exist. Connect ohmmeter between terminals No. 87 and 30. Continuity should not exist.
3. Using a pair of jumper wires, connect a jumper wire between terminal No. 85 and battery ground. Connect other jumper wire to battery positive terminal, but DO NOT connect to relay yet. CAUTION: DO NOT allow ohmmeter to contact terminal No. 85 or 86 during following test. Damage to ohmmeter may result.
4. Attach other jumper wire to relay terminal No. 86 to activate relay. Continuity should exist between terminals No. 87 and 30, but not between terminals No. 87A and 30. Disconnect jumper wires from battery and relay.

Scheme 134

High-Pressure Fuel Shutoff Solenoid

Solenoid is located on fuel pressure regulator. Disconnect solenoid harness connector. Using jumper wires, momentarily connect battery power across solenoid terminals (polarity not important). Solenoid should click. If solenoid does not click, replace fuel pressure regulator assembly.

Low-Pressure Fuel Shutoff Solenoid

1. Solenoid is located on bracket in engine compartment.
2. Disconnect solenoid harness connector. Using jumper wires, momentarily connect battery power across solenoid terminals (polarity not important). Solenoid should click. If solenoid does not click, replace low-pressure fuel shutoff solenoid.

FUEL DELIVERY

Note. For fuel system pressure testing, see appropriate BASIC TESTING - 5.2L CNG article in the ENGINE PERFORMANCE section.

Fuel Injector

Disconnect fuel injector connector. Using a DVOM in ohmmeter position, test between pins of injector for resistance. If resistance is NOT 4.2-5.0 ohms, replace fuel injector.

See also:
• TESTS W/CODES - 5.2L CNG
• THEORY/OPERATION - 5.2L CNG
• BASIC TESTING - 5.2L CNG
• SYSTEM/COMPONENT TESTS - 5.2L CNG