Engine Controls - System/component Tests - Gasoline Dodge Caravan II

INTRODUCTION

Note. Testing procedures not covered in this article require a Chrysler Diagnostic Readout Box II (DRB-II). See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

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

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.

Harness Check

1. If SBEC is found to be faulty during SELF-DIAGNOSTICS testing, perform following steps to confirm diagnosis. Most components are incorrectly diagnosed due to faulty electrical connectors or poor connections between component and vehicle. Sometimes, simply disconnecting and connecting an electrical component will provide a good electrical connection.
2. Before replacing an SBEC, check all components in suspected circuit. If components are okay, carefully disconnect SBEC from vehicle harness.
3. Inspect SBEC harness connector and SBEC contact pins for corrosion, bent pins, missing pins, spread cavities and broken wires. Clean, repair or replace connector as necessary.
4. Connect SBEC harness connector to SBEC, and retest system using Diagnostic Readout Box (DRB-II) or similar scan tool. See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section. If vehicle does not pass test and fails with same message, replace SBEC.

Air Temperature Sensor

See THERMOSTATIC AIR CLEANER under EMISSION SYSTEMS & SUB-SYSTEMS.

Charge Air Temperature Sensor (CAS)

Sensor is mounted in intake manifold, under throttle cable bracket at throttle body. With key off, disconnect wire connector from sensor. Connect ohmmeter between sensor terminals. See TEMPERATURE SENSOR RESISTANCE table. If readings are not within specification, replace CAS sensor.

Coolant Temperature Sensor (CTS)

Sensor is mounted in intake manifold, next to thermostat housing. With key off, disconnect wire connector from sensor. Connect ohmmeter between sensor terminals. See TEMPERATURE SENSOR RESISTANCE table. If ohmmeter readings are not within specification, replace CTS.

TEMPERATURE SENSOR RESISTANCE

Crankshaft Position Sensor (CPS)

CPS is bolted to cylinder block near rear of right cylinder head. Disconnect CPS connector from main wiring harness. Measure resistance across CPS wiring connector terminals "B" and "C". (Scheme 114) Replace CPS if any resistance exists.

Scheme 114

Idle Position Switch

1. Idle position switch is located on throttle body. Disconnect idle position switch connector. Using an ohmmeter, check continuity between switch terminal and ground.
2. With accelerator pedal depressed, continuity should not exist. With accelerator pedal released, continuity should exist. Replace idle position switch if it does not test as specified.

Manifold Absolute Pressure (MAP) Sensor

1. MAP sensor is connected to side of throttle body by a rubber fitting. Inspect rubber fitting, and repair as needed. NOTE: MAP sensor test must be performed with wiring connector connected.
2. Measure MAP sensor output voltage at connector center terminal. With ignition switch in ON position, output voltage should be 4.0-5.0 volts. With ignition switch in RUN position, voltage should be 1.5-2.1 volts. Replace MAP sensor if it does not test as specified.

Oxygen (O2) Sensor

Oxygen sensor is located at outlet of exhaust manifold. Warm engine until coolant temperature reaches 185-205°F (85-95°C). Disconnect oxygen sensor connector, and connect a voltmeter to connector. With engine speed more than 1300 RPM, measure oxygen sensor output voltage. Voltage should be .6-1.0 volt. If voltage is not within specification, replace oxygen sensor.

Park/Neutral Switch

1. Park/neutral switch is located on transmission. Turn ignition off. Put shift selector in PARK position. Disconnect SBEC connector. Disconnect starter relay connector (located in engine compartment).
2. Using an ohmmeter, backprobe cavity No. 30 in SBEC connector while moving shift selector in and out of PARK and REVERSE positions. (Scheme 115) If reading varies from less than 5 ohms to more than 5 ohms, replace ignition switch. If reading is always less than 5 ohms, check Brown/Yellow wire for short to ground.
3. If reading is always more than 5 ohms, disconnect park/neutral switch connector. Check resistance in Brown/Yellow wire. If resistance is less than 10 ohms, replace park/neutral switch. If resistance is more than 10 ohms, check Brown/Yellow wire for open.

Scheme 115

Throttle Position Sensor (TPS)

1. TPS is located on throttle body. Disconnect and inspect TPS connector. Repair as necessary. With ignition switch in the ON position, measure output voltage at center terminal (output) wire of connector.
2. At idle, TPS output should read more than 200 millivolts. At Wide Open Throttle (WOT), TPS output must read less than 4.8 volts. Output voltage should increase gradually as throttle is increased from idle to WOT. If voltage readings are not within specification, replace TPS.

Vehicle Speed Sensor (VSS)

VSS is located on transmission extension housing on 2WD models. VSS is located on transfer case on 4WD models. For VSS testing, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

Ignition Module

See appropriate BASIC TESTING article in the ENGINE PERFORMANCE Section.

Idle Speed Control (ISC) Motor

See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

Auto Shutdown (ASD) Relay

1. ASD relay is located in engine compartment. Relay terminal numbers are stamped on bottom of relay. Relay must be disconnected for testing. 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.
3. Connect ohmmeter between terminals No. 87A and 30. Continuity should exist. Connect ohmmeter between terminals No. 87 and 30. Continuity should not exist.
4. 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.
5. 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.

Torque Converter Lock-Up Relay

See TRANSMISSION under MISCELLANEOUS CONTROLS.

EGR Solenoid

See EMISSION SYSTEMS & SUB-SYSTEMS.

Torque Converter Lock-Up Solenoid

See TRANSMISSION under MISCELLANEOUS CONTROLS.

FUEL DELIVERY

Note. For fuel system pressure testing, see appropriate BASIC TESTING 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 less than 10 ohms, replace throttle body injector wiring. If resistance is more than 10 ohms, replace fuel injector.

See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

IGNITION SYSTEM

Note. For basic ignition checks, see appropriate BASIC TESTING article in the ENGINE PERFORMANCE Section.

EMISSION SYSTEMS & SUB-SYSTEMS

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

No Air Supply

1. Start engine, and raise engine speed to 1500 RPM. Check air supply at rubber hoses. If air supply increases with RPM, air pump operation is okay. If air pump is okay, check for leakage at hoses and fittings. Repair or replace as necessary.
2. If hoses are okay, check diverter valve for leakage. If air is expelled through diverter exhaust with vehicle at idle, replace diverter valve. If diverter valve is okay, remove check valve. Blow air through check valve in direction of air pump. Air should not pass through. Blow air through opposite direction. Air should pass freely.

Air Supply Pump

Check and adjust belt tension (if necessary). Disconnect air supply hose from by-pass control valve. Start engine. Pump is operating correctly if airflow is felt at pump outlet and airflow increases as engine speed increases. If pump does not operate as specified, replace pump.

EXHAUST GAS RECIRCULATION (EGR)

Note. To ensure proper EGR system operation all passages and moving parts must be free from restrictive deposits. Clean or replace components as necessary.

EGR System Operation Check

1. Warm engine to operating temperature. Attach a tachometer to engine. Run engine at idle in Neutral an additional 70 seconds.
2. Accelerate engine speed abruptly to 2000-3000 RPM, and check EGR valve stem for movement. Repeat test to confirm stem movement, indicating EGR control system is functioning correctly. If EGR valve stem does not move, connect external vacuum source and recheck EGR valve stem for movement. If EGR operates normally on external vacuum source, go to step 6).
3. If EGR valve stem does not move, check for cracked, leaking, disconnected or plugged vacuum hoses. Verify correct hose routing. Disconnect hose harness from EGR valve/transducer, and connect a vacuum pump to harness.
4. Start engine, and raise engine speed to 2000 RPM and hold. Apply 10 in. Hg. vacuum to EGR while checking for EGR valve movement. If no movement occurs, replace EGR valve/transducer assembly.
5. If valve opens approximately 1/8" (3 mm), hold vacuum constant and check for valve diaphragm leakage. Valve should remain open for at least 30 seconds. If leakage occurs, replace valve/transducer assembly. If valve is okay, check control system.
6. If EGR valve stem does not move in step 2) but operates normally on external vacuum source, remove throttle body and check port in throttle bore for blockage. Use a solvent to remove deposits, and check flow using light air pressure. Normal operation should be restored.
7. If engine will not idle correctly or stalls, check for leaking EGR valve. With engine running, remove vacuum hose from EGR valve. If removing vacuum hose does not correct rough idle, remove EGR valve/transducer assembly. Check valve for proper seating. Replace assembly as necessary.
8. Also check EGR-to-intake manifold tube for leak. Remove tube and inspect gasket. Tube end should be uniformly indented on gasket, without signs of leakage. If leakage is not evident, replace gaskets and tighten flange nuts to 17 ft. lbs. (23 N.m). If leak persists, replace EGR tube and gaskets.

Note. DO NOT use drills or wires to clean passages for EGR control system. Calibration of precision orifices could be altered, resulting in unsatisfactory vehicle operation.

1. EGR solenoid is located in engine compartment. With ignition switch in OFF position, disconnect and inspect solenoid connector. Repair as necessary. If connector is okay, turn ignition switch to ON position.
2. Using a DVOM in voltmeter mode, backprobe Dark Green/Orange wire. If voltage is less than 10 volts, check for open in Dark Green/Orange wire. If voltage is more than 10 volts, turn ignition switch to OFF position. Connect EGR solenoid connector. Disconnect and inspect SBEC connector. Repair as necessary.
3. Turn ignition switch to ON position. With DVOM in voltmeter mode, backprobe SBEC cavity No. 35. (Scheme 115) If voltage is more than 10 volts, replace SBEC. If voltage is less than 10 volts, turn ignition switch to OFF position. Disconnect EGR solenoid connector.
4. Using an ohmmeter, backprobe cavity No. 35 on SBEC. If resistance is less than 10 ohms, check Gray/Yellow wire for short to ground. If resistance is more than 10 volts, test resistance in Gray/Yellow wire. If resistance is less than 10 ohms, replace EGR solenoid. If resistance is more than 10 ohms, check Gray/Yellow wire for open.

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.

EVAP Solenoid

1. EVAP solenoid is located in engine compartment. Turn ignition switch to OFF position. Disconnect and inspect solenoid connector. Repair as necessary.
2. Turn ignition switch to ON position. Using DVOM in voltmeter mode, backprobe Dark Brown wire at connector. If voltage is less than 10 volts, check for open in Dark Brown wire. If voltage is more than 10 volts, turn ignition switch to OFF position. Connect solenoid connector. Disconnect and inspect SBEC connector. Repair as necessary.
3. Turn ignition switch to ON position. With DVOM in voltage mode, backprobe cavity No. 52 on SBEC connector. (Scheme 115) If voltage is more than 10 volts, replace SBEC. If voltage is less than 10 volts, turn ignition switch to OFF position. Disconnect solenoid connector. Using an ohmmeter, backprobe cavity No. 52 on SBEC connector.
4. If resistance is less than 10 ohms, check Pink/Black wire for short to ground. If resistance is more than 10 ohms, test Pink/Black wire for resistance. If resistance is less than 10 ohms, replace EVAP solenoid. If resistance is more than 10 ohms, check Pink/Black wire for open.

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.

THERMOSTATIC AIR CLEANER

Note. With engine cold, heat control door in air cleaner snorkel should be closed. With engine running at normal operating temperature, door should be open.

Ensure all vacuum hoses are in good condition. Using external vacuum source, apply 20 in. Hg vacuum to air temperature sensor. Door should be in open position. If door is not open, check vacuum diaphragm for leaks and restrictions. If diaphragm is okay but proper temperature is not maintained, replace temperature sensor.

Air Control Door

Apply 20 in. Hg vacuum to diaphragm. Diaphragm should not bleed down more than 10 in. Hg in 5 minutes. Door should not lift off bottom at less than 2 in. Hg. Door should be fully open at no more than 4 in. Hg. If vacuum diaphragm does not operate properly, replace vacuum diaphragm and repeat test.

MISCELLANEOUS CONTROLS

Note. Although some controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

A/C Clutch Relay (Except Dakota)

1. A/C clutch relay is located in engine compartment. Turn ignition switch to ON position. Using a DVOM in voltmeter mode, backprobe Dark Blue/Orange wire atA/C clutch relay. (Scheme 116) If voltage is more than 10 volts, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section. If voltage is less than 10 volts, turn ignition switch to OFF position. Disconnect and inspect clutch relay connector. Repair as necessary.
2. If connector is okay, backprobe Light Green wire in clutch relay connector. If voltage is less than 10 volts, check for open in Light Green wire. If voltage is more than 10 volts, using an ohmmeter, backprobe Dark Blue/Orange wire in clutch relay connector. If resistance is less than 10 volts, check Dark Blue/Orange wire for short to ground. If resistance is more than 10 volts, replace A/C clutch relay.

Scheme 116

A/C Clutch Relay (Dakota)

1. A/C clutch relay is located at power distribution center in engine compartment. Turn ignition switch to ON position. Actuate A/C switch on dash panel. If A/C clutch relay clicks, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.
2. If A/C clutch relay does not click, disconnect and inspect clutch relay connector. Repair as necessary. If connector is okay, replace clutch relay. Actuate A/C switch on dash. If clutch relay clicks, repair is complete. If clutch relay does not click, remove clutch relay.
3. Using DVOM in voltage mode, backprobe cavity "A" in relay connector. (Scheme 117) If voltage is less than 10 volts, check for open in Light Green wire. If voltage is more than 10 volts, turn ignition switch to OFF position.
4. Reconnect A/C clutch relay. Disconnect and inspect SBEC connector. Repair as necessary. If connector is okay, turn ignition switch to ON position. Using DVOM in voltage mode, backprobe cavity No. 34 on SBEC connector. (Scheme 115) If voltage is more than 10 volts, replace SBEC. If voltage is less than 10 volts, check for open in Dark Blue/Orange wire.

Scheme 117

1. Torque converter lock-up relay is located in engine compartment. Turn ignition switch to ON position. Using a DVOM in voltmeter mode, backprobe Orange/Black wire at relay. If voltage is more than 10 volts, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section. If voltage is less than 10 volts, disconnect and inspect relay connector. Repair as necessary.
2. If connector is okay, backprobe Dark Blue wire at relay. If voltage is more than 10 volts, replace lock-up relay. If voltage is less than 10 volts, repair open in Dark Blue wire.

1. Lock-up solenoid is located on left side of transmission. Turn ignition switch to OFF position. Disconnect solenoid connector from transmission. Inspect connector, and repair as necessary.
2. If connector is okay, turn ignition switch to ON position. Using DVOM in voltage mode, backprobe Dark Blue wire on connector. If voltage is less than 10 volts, check for open Dark Blue wire. If voltage is more than 10 volts, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE SECTION.