INTRODUCTION
Before testing individual components or systems, perform procedures in BASIC TESTING - 3.9L article. Since many computer controlled and monitored components set a fault message if they malfunction, also perform procedures in TESTS W/CODES - 3.9L article.
Note. Testing of individual components does not isolate possible shorts or opens in wiring harness of electronically controlled systems. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance unless otherwise instructed in procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
POWERTRAIN CONTROL MODULE (PCM)
The PCM power and ground circuits may be checked by performing TEST NTC-11A in TESTS W/CODES - 3.9L article. For PCM location, see PCM LOCATION table.
| Application | Location |
|---|---|
| Van/Wagon | On Firewall, Near Blower Motor |
PCM LOCATION
Camshaft Position (CMP) Sensor
See TEST TC-1A in TESTS W/CODES - 3.9L article.
Crankshaft Position (CKP) Sensor
See TEST TC-40A in TESTS W/CODES - 3.9L article.
Engine Coolant Temperature (ECT) Sensor
See TEST TC-30A and TC-31A in TESTS W/CODES - 3.9L article.
Heated Oxygen Sensor (HO2S)
See Trouble Code (TC) TEST in TESTS W/CODES - 3.9L article.
Intake Air Temperature (IAT) Sensor
See TEST TC-57A and TC-58A in TESTS W/CODES - 3.9L article.
Manifold Absolute Pressure (MAP) Sensor
See TEST TC-36A and TC-37A in TESTS W/CODES - 3.9L article.
Throttle Position (TP) Sensor
See Trouble Code (TC) TEST in TESTS W/CODES - 3.9L article.
Vehicle Speed Sensor (VSS)
See Trouble Code (TC) TEST in TESTS W/CODES - 3.9L article.
Park/Neutral Position Switch
See TEST TC-114A in TESTS W/CODES - 3.9L article.
A/C Clutch Relay, Auto Shutdown (ASD) Relay & Fuel Pump Relay
See Trouble Code (TC) TEST in TESTS W/CODES - 3.9L article.
FUEL DELIVERY
Note. For fuel system pressure testing, see appropriate TESTS W/CODES - 3.9L article.
Fuel Injector
See TEST TC-21A in TESTS W/CODES - 3.9L article.
IDLE AIR CONTROL (IAC) MOTOR
See TEST TC-25A in TESTS W/CODES - 3.9L article.
IGNITION SYSTEM
Note. For basic ignition checks, see TEST NTC-2A in TESTS W/CODES - 3.9L article.
EMISSION SYSTEMS & SUB-SYSTEMS
Note. To locate emission components, refer to emission control information label in engine compartment.
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. Noliquid should be in canister.
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 device listed here is not technically an engine performance component, it can affect driveability if it malfunctions.
A/C Clutch Relay
See RELAYS.
See also:
• BASIC TESTING - 3.9L
• TESTS W/CODES - 3.9L