Engine Controls - System/component Tests - Gasoline Ford Explorer I

MODEL IDENTIFICATION

Note. Unless otherwise specified, references to Pickup include the F350 Super Duty commercial chassis.

MODEL IDENTIFICATION

INTRODUCTION

Prior to testing separate components or systems, it is recommended that all procedures listed in BASIC TESTING article in the ENGINE PERFORMANCE Section be performed. Since many computer controlled and monitored components will set a service code if they malfunction, check EEC-IV system and retrieve service codes. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If service codes are present see appropriate CIRCUIT TEST in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

Note. Testing individual components does not isolate wiring circuit shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) that has a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

Note. For wiring diagrams not shown in testing procedures, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

Ground Circuits

1. Using a DVOM, check for continuity to ground on ECA terminals No. 20, 40 and 60. (Scheme 54) Resistance should be zero ohms. If resistance is not zero ohms, repair open to ground.
2. Using a voltmeter, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If volt-meter reading is greater than one volt, check for open, corrosion or loose connection on ground lead.

Power Circuits

Using a voltmeter, check for battery voltage between ECA terminal No. 1 (KAPWR) and ground. Check for battery voltage at terminals No. 37 and 57 (VPWR). If battery voltage is not present, power is not being supplied from EEC power relay. See CIRCUIT TEST B in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

ECA LOCATION (1)

Scheme 54

Scheme 55

Scheme 56

Scheme 57

Scheme 58

ENGINE SENSORS & SWITCHES

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS article in the ENGINE PERFORMANCE section.

Air Charge Temperature (ACT) Sensor

1. Sensor is located in intake runner. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. NOTE: Engine Coolant Temperature (ECT) sensor and ACT sensor terminal connectors are identical. Ensure testing is done on proper component.
2. For specifications, see SENSOR RANGE CHARTS article in the ENGINE PERFORMANCE Section. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

Barometric Pressure Sensor (BP)

Faults in barometric pressure sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DF in TESTS W/CODES article in the ENGINE PERFORMANCE Section for sensor specifications.

Clutch Switch

See NEUTRAL DRIVE SWITCH (NDS) A/C INPUT.

Cylinder Identification Sensor (CID) & Crankshaft Sensor

CID sensor is mounted at crankshaft. Disconnect sensor connector and measure resistance across sensor terminals. Resistance should be 300-750 ohms. If resistance is not as specified, replace sensor.

Engine Coolant Temperature (ECT) Sensor

Sensor is located in intake manifold coolant passage at front of most engines. On 2.3L, sensor is mounted on left side of engine, above oil filter. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. For specifications, see SENSOR RANGE CHARTS article in the ENGINE PERFORMANCE Section. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

EGR Valve Position (EVP) Sensor/EGR Vacuum Regulator (EVR)

Solenoid

Faults in sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DN in TESTS W/CODES article in the ENGINE PERFORMANCE Section for sensor specifications and circuit testing procedure.

Engine RPM Sensor (RPMS)

This sensor is used only on diesel engines. Disconnect RPMS electrical connector. Using DVOM, measure resistance across sensor terminals. Resistance should be 2400-2800 ohms. Replace sensor if not as specified. Faults in RPMS or sensor circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DJ in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor testing and specifications.

Heated Exhaust Gas Oxygen (HEGO) Sensor

Vehicle may be equipped with one or 2 HEGO sensors. They are located in the exhaust pipe upstream of the catalytic converters. Faults in sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST H in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor specifications and circuit testing procedures. Ensure that none of the following conditions exist.

1. Moisture inside sensor/harness connector
2. HEGO sensor coated with contaminants
3. Sensor circuit open or shorted to ground

Inertia Switch

Ensure key is off. Inertia switches may be found in the following locations

1. On Aerostar & Van, on right kick panel, just forward of door opening.
2. On Bronco & Pickup, on floorboard to left and above steering column.
3. On Explorer, under instrument panel, to right of transmission hump.

Push down on reset button to ensure switch is closed. Measure resistance between terminals on switch. If resistance is 5 ohms or less, switch is okay. For additional circuit testing information refer to CIRCUIT TEST J in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If resistance is greater than 5 ohms, replace switch.

Note. In closed position, reset button can be depressed an additional 1/16" against spring. This is normal and does not affect switch operation.

Knock Sensor (KS)

KS is located on cylinder block. Faults in sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DG in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor specifications and circuit testing procedures. Sensor is tested by substitution or by manually generating a knock to ensure sensor will set a service code.

Manifold Absolute Pressure (MAP) Sensor

Sensor is located on engine or firewall and is connected to intake manifold by a vacuum supply hose. Remove vacuum supply hose to sensor. Install vacuum pump to sensor and apply 18 in. Hg vacuum. Sensor should hold vacuum. If sensor does not hold vacuum, replace sensor. Faults in MAP sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DF in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor testing and specifications.

Mass Airflow (MAF) Sensor

Faults in MAF sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DC in TESTS W/CODES article in the ENGINE PERFORMANCE Section for sensor and circuit testing and specifications.

Neutral Drive Switch (NDS) A/C Input

With ignition switch in OFF position, set DVOM to 200-ohm scale. Locate NDS switch (on transmission) and clutch switch (on clutch pedal linkage). Disconnect harness at both switches. Measure resistance across NDS terminals with transmission in Neutral and across clutch switch terminals with clutch pedal fully depressed. If any resistance is greater than 5 ohms, switch is open. Replace switch as necessary. Faults in switches or switch circuits should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST TA in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional switch testing and specifications.

Power Steering Pressure Switch (PSPS)

1. Disconnect PSPS connector at steering gearbox or line. Set DVOM to 200-ohm scale and connect test leads to switch. With steering wheel centered, resistance should be less than 10 ohms. Start engine and turn steering wheel one-half turn and then return it to centered position.
2. Resistance should change from less than 10 ohms to infinity and return to less than 10 ohms when steering wheel is returned to centered position. Faulty PSPS or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST FF in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional switch testing and specifications.

Throttle Position Sensor (TP Or TPS Gasoline)

For diesel TPS, see FUEL INJECTION PUMP LEVER (FIPL) SENSOR. Faults in TP sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DH in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor testing and specifications. Ensure none of the following conditions exist

1. Binding throttle linkage
2. TP sensor loose or not seated properly
3. Throttle plate not fully closed

Vehicle Speed Sensor (VSS)

Disconnect VSS electrical connector. Using DVOM measure resistance across sensor terminals. Resistance should be 190-250 ohms. Replace sensor if not within specification. Faults in VSS sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DP in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional sensor testing and specifications.

Fuel Pump Relay

Remove relay from vehicle. Connect battery voltage to terminal "C". Ground terminal "D". (Scheme 59) Measure resistance between terminals "A" and "B". Resistance should be less than one ohm with power applied and greater than 10 k/ohms with power removed.

Note. For more fuel delivery system testing, see CIRCUIT TEST J in TESTS W/CODES article in the ENGINE PERFORMANCE section.

Scheme 59

Air Management Solenoids (AM1 & AM2)

Disconnect solenoid harness connectors, and measure resistance across terminals. Resistance should be 50-100 ohms. If resistance is not as specified, replace solenoid. Faults in AM1 or AM2 solenoids or circuits should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST KC in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional solenoid and circuit testing.

Canister Purge (CANP) Solenoid

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

EGR Solenoid

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

Idle Speed Control (ISC) Solenoid

1. Solenoid is by-pass air type. Ensure ignition is off. Disconnect ISC solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance between ISC solenoid terminals. (Scheme 60) There is a diode in solenoid, connect DVOM (+) test lead to VPWR terminal and DVOM (-) lead to ISC terminal.
2. Resistance should be 7-13 ohms. If resistance is not as specified, replace solenoid. Faults in ISC solenoid or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST KE in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional solenoid testing and specifications.

Scheme 60

FUEL SYSTEM

Note. In testing procedures, references to KOEO refer to Key On Engine Off. References to KOER refer to Key On Engine Running.

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (Schrader valve), located on fuel injection manifold rail.
2. If fuel pressure gauge is not available, disconnect electrical connector to inertia switch located on left side of luggage compartment. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to release system pressure.

FUEL DELIVERY

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Note. For fuel system pressure testing and fuel pressure specifications, see BASIC TESTING article in the ENGINE PERFORMANCE Section.

See MODULES, MOTORS, RELAYS & SOLENOIDS.

Scheme 61

1. Visually inspect entire fuel delivery system for leaks, damaged or kinked lines and hoses. Ensure battery is fully charged and fuses are okay. Ensure adequate fuel is available in fuel tank. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/ford/explorer/i-1990-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-gasoline__fuel-system-pressure-release). Install fuel pressure gauge. With Key On Engine Off (KOEO) to activate pump, check and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/ford/explorer/i-1990-1994/remont/specifications/#fuel-pressure-specifications) article. Proceed to appropriate step, as indicated: If fuel pressure is within specification, go to step 2). If fuel pressure is zero, go to step 5). If fuel pressure is low, go to step 11). If fuel pressure is high, go to step 12).
2. Check fuel injectors. See FUEL CONTROL. Crank or run engine. Using a mechanic's stethoscope, listen for regularly spaced operating sounds at each injector. If sound is present, check fuel injectors for flow and leakage. Clean or replace injectors as necessary.
3. If injector operating sound is not present, check fuel injector resistance. See FUEL CONTROL. If injector is not within specification, replace as necessary. If injector is within specification, check injector electrical connections for continuity to ECA. If no continuity exists in circuit, check for 12 volts at each injector lead.
4. If voltage is not present at injector, see Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. Faults in injector circuit should set a service code. If no service code has been set, see CIRCUIT TEST H in TESTS W/CODES article in the ENGINE PERFORMANCE Section.
5. If fuel pressure is zero, ensure battery is fully charged and key is off. Ground fuel pump lead. Using a jumper lead, ground FP terminal at SELF-TEST connector. (Scheme 61) Ensure connection is okay at pump/sender unit. Turn ignition on, engine off. Listen for sound of fuel pump running. If pump is running, proceed to next step. If fuel pump is not running, proceed to step 7).
6. Check condition of high-pressure fuel filter. If filter is free of contamination check fuel pressure regulator, go to step 12). If filter is contaminated, replace filter and recheck system pressure as outlined in step 1).
7. Turn ignition off and disconnect fuel pump/sender or high pressure pump connector. Set DVOM on 200-ohm scale. Measure resistance between pump ground at connector and chassis ground. If resistance is one ohm or more, repair open circuit to ground. If resistance is less than one ohm, go to next step.
8. Ensure ignition is off and battery is fully charged. Disconnect harness connector from pump/sender unit. Ground FP terminal at SELF-TEST connector. With KOEO and DVOM on 20-volt scale, measure voltage at Pump Power terminal of pump/sender or high pressure pump connector. If voltage is 10.5 volts or more, replace pump/sender assembly. If voltage is not as specified, go to next step.
9. With KOEO, check voltage at fuel pump inertia switch. If voltage is 10.5 volts or more at both inertia switch terminals, repair wire between inertia switch and pump. If voltage is not as specified, reset or replace inertia switch as necessary and go to next step.
10. Ensure ignition is off and battery is fully charged. Ground FP terminal at SELF-TEST connector. With KOEO and DVOM on 20-volt scale, measure voltage at fuel pump relay (Brown wire). If voltage is 10.5 volts or more at relay, repair Brown wire between fuel pump relay and inertia switch. If voltage is not as specified, check voltage supply to fuel pump relay and to terminal No. 1 at ECA. For additional circuit testing information see CIRCUIT TEST J in TESTS W/CODES article in the ENGINE PERFORMANCE Section.
11. Ground FP terminal at SELF-TEST connector. Using a DVOM, check voltage at fuel pump terminal (Pink/Black wire). If voltage at fuel pump is within.5 volt of battery voltage, go to step 6). If voltage is not as specified, go to step 5).
12. Check engine compartment vacuum hose for leaks and ensure engine produces normal engine vacuum. See appropriate FUEL PRESSURE REGULATOR test procedure.

Scheme 62

1. Ensure key is off. Connect fuel pressure gauge to Schrader valve on fuel rail. Ensure manifold vacuum supply tube is connected to fuel pressure regulator. Start and run engine for 10 seconds. Stop engine and wait 10 seconds. Start and operate engine for 10 seconds. Stop engine and remove pressure regulator vacuum hose. (Scheme 62) Check vacuum port for fuel.
2. If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, start and run engine for 30 seconds. Stop engine and check fuel pressure gauge. If fuel pressure does not drop, go to step 4). If fuel pressure drops more than 5 psi (.4 kg/cm 2 ) in 60 seconds, disconnect and plug fuel return line at engine. Cycle ignition key on and off until normal fuel pressure is obtained.
3. Turn key off and check fuel pressure gauge. If gauge drops more than 5 psi (.4 kg/cm 2 ) in 30 seconds, replace high pressure fuel pump (dual pump system) or fuel sender/pump assembly (single pump type). If gauge does not drop more than 5 psi (.4 kg/cm 2 ) in 30 seconds, replace fuel pressure regulator.
4. Ensure key is off. Relieve fuel pressure. Remove fuel pressure regulator. Check "O" ring, gasket and mounting surfaces for cracks, cuts or other damage. Connect vacuum pump to fuel return tube and apply 20 in. Hg. If maximum vacuum loss exceeds 10 in. Hg in 10 seconds, replace regulator. If maximum vacuum loss does not exceed 10 in. Hg in 10 seconds, recheck entire fuel delivery system for cause of fuel pressure loss.

Fuel Selector Valve (Diesel)

1. Disconnect electrical connector from tank selector valve. Turn ignition to RUN position. Move selector switch to FRONT position and check for voltage at selector valve terminals No. 1 and 2. (Scheme 63) If voltage is present, go to step 2). If voltage is not present, check fuse No. 15 (10A) or related circuit.
2. Check voltage between selector valve motor terminal No. 2 and ground. If voltage is present, go to step 3). If voltage is not present, check fuse No. 15 (10A) or related circuit. Replace fuse or repair circuit as necessary. Test system. If system is still inoperative, go to next step.
3. Jumper selector valve terminal No. 2 to battery positive and terminal No. 1 to frame ground. (Scheme 63) Valve motor should operate. Reverse jumper leads to motor. Motor should operate in opposite direction. If motor does not operate in one or both directions, replace fuel selector valve assembly.

Scheme 63

Fuel Selector Valve (Gasoline)

Fuel selector valve is mechanically operated and uses in-tank pump pressure to control fuel supply and return. Front or rear tank indication is controlled by the selector switch.

Fuel Injectors

1. Connect tachometer to engine. Run engine at idle. Disconnect and reconnect injectors individually. If each injector causes a momentary drop in engine speed of at least 100 RPM, injectors are giving proper fuel delivery. RPM drop should only be momentary as ISC will attempt to re-establish correct idle RPM.
2. Replace any injectors that do not cause sufficient drop in engine speed. When test is complete and all injectors cause equal drop in speed, shut off engine. In order to check curb idle, refer to emission control specifications on decal in engine compartment.

Injector Circuit

1. Disconnect all injector harness connectors. Using a DVOM, check resistance across terminals of each injector. See «INDIVIDUAL INJECTOR RESISTANCE»(/ford/explorer/i-1990-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-gasoline) .
2. Disconnect injector bank harness connector, and check resistance of injector bank. See «INJECTOR BANK RESISTANCE»(/ford/explorer/i-1990-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-gasoline) . Repair wiring or replace any injector circuit not within specification.

INDIVIDUAL INJECTOR RESISTANCE

INJECTOR BANK RESISTANCE

IDLE CONTROL SYSTEM

Note. See IDLE SPEED CONTROL (ISC) SOLENOID test procedures under SOLENOIDS. Curb idle and fast idle speed is controlled by ECA and is not adjustable. Some throttle bodies have a sludge-tolerant design with a special coated throttle bore. A Yellow/Black warning decal on these units warns against backing off throttle plate adjustment screw to avoid throttle plate sticking in bore. Faults in idle control system components or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

IGNITION SYSTEMS

Note. For additional information and descriptions see IGNITION SYSTEMS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section. Perform spark output check in TESTS W/O CODES article in the ENGINE PERFORMANCE Section before entering these tests. Some ignition systems require that Quick Test procedure be performed prior to testing. This will retrieve trouble codes from the EEC-IV system. See TESTS W/CODES article in the ENGINE PERFORMANCE Section.

IGNITION SYSTEM ACRONYMS (1)

IGNITION SYSTEM IDENTIFICATION

(2.9L & 3.0L RANGER, 3.0L AEROSTAR & 4.9L, 5.0L, 5.8L & 7.5L BRONCO, PICKUP & VAN)

Note. Before testing components and circuits of this system, ensure system is identified as to location of TFI module (distributor mounted or CBD type) and if dwell is controlled by TFI module or ECA (Non-CCD or CCD type). Additional system and circuit testing for this system is located in appropriate CIRCUIT TESTS in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

Preliminary Check

Ensure the following preliminary checks have been performed

1. Visually inspect engine compartment to ensure all vacuum hoses and spark plug wires are properly routed and securely connected.
2. Examine all wiring harnesses and connectors for damage.
3. Ensure TFI module is securely fastened to distributor base or cowl.
4. Ensure battery is fully charged.
5. Turn all accessories off during diagnosis.

Test Equipment

The following test equipment or equivalent should be used in TFI-IV ignition system tests.

1. Spark Tester (D81P-6666-A)
2. Volt-Ohmmeter
3. 12-Volt Test Light
4. Small Straight Pin
5. Remote Starter Switch
6. E-Core Ignition Coil (E73F-12029-AB)
7. Ignition Coil Secondary Wire

Diagnostic Aids

Following information should be noted during testing

1. A spark plug with a broken side electrode is NOT sufficient to check for spark and may lead to incorrect results.
2. When instructed to inspect a wiring harness, both a visual inspection and a continuity test should be performed.
3. When making measurements on a wiring harness or connector, perform a WIGGLE test while measuring.
4. References to SPOUT in-line connector apply to both in-line and shorting-bar type connectors.
5. Test procedures are intended to identify faulty components or wiring while fault is present. If complaint is an intermittent condition, refer to TESTS W/O CODES article in the ENGINE PERFORMANCE Section.

Scheme 64

1. Disconnect terminal "S" at starter relay to allow testing of ignition primary circuit without cranking motor. Ensure ignition is off. Push down on connector tab and disconnect harness connector from TFI module. Ensure TFI module connector is not corroded or swollen. Repair or replace connector as necessary. NOTE: If connector is damaged or has broken tabs due to misuse, replace connector. A loose or damaged connector may cause ignition signal faults during KOER operation.
2. Use a straight pin or terminal spade from an old TFI module to probe connector. Attach negative DVOM lead to distributor base. Avoid ground contact with straight pin or positive terminal lead during testing. Turn ignition on and measure voltage at following TFI module harness connector terminals: (Scheme 64) Key On Engine Cranking (KOEC) No. 3 (Power/Run Circuit) No. 4 (Start Circuit) Key On Engine Off (KOEO) No. 3 (Power/Run Circuit)
3. Turn ignition off and remove test pin. Reconnect wire to "S" terminal on relay. If approximately 90% of Battery Voltage (VBAT) is not present at these terminals, repair open circuits in wiring harness as necessary. Check ignition switch for faults. See appropriate wiring diagram. If voltage was as specified, reconnect module and go to next step.
4. Attach a 12-volt test light between ground and coil negative (-)/tach terminal No. 2 at TFI module. Turn ignition on, and crank engine. If test light flashes brightly during cranking, go to appropriate PIP SENSOR/STATOR TEST. If test light stays on during cranking, check for open in coil negative circuit between coil and TFI module connector. Repair circuit as necessary. If no open circuits are found, ignition module is shorted internally. Replace TFI module and retest.
5. If test light is always dim or off during cranking, check voltage to coil positive (+) terminal. If voltage is not present with key on or during cranking, repair open in primary circuit between battery and coil positive (+). If light flashes intermittently, check ignition module resistance. If voltage is available at coil, go to COIL TEST and check ignition coil.

Scheme 65

1. Disconnect terminal "S" at starter relay to allow testing of ignition primary circuit without cranking motor. Ensure ignition is off. Push down on connector tab and disconnect harness connector from TFI module. Ensure TFI module connector is not corroded or swollen. Repair or replace connector as necessary. NOTE: If connector is damaged or has broken tabs due to misuse, replace connector. A loose or damaged connector may cause ignition signal faults during KOER operation.
2. Use a straight pin or terminal spade from an old TFI module to probe connector. Avoid ground contact, between straight pin and ground, during testing. Using a DVOM, turn ignition on and measure voltage at following vehicle harness connector terminals of cowl mounted TFI module: (Scheme 64) Key On Engine Cranking (KOEC) No. 3 (Power/Run Circuit) No. 4 (Start Circuit) Key On Engine Off (KOEO) No. 3 (Power/Run Circuit) If approximate Battery Voltage (VBAT) is not present at these terminals, repair open circuits in wiring harness as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.
3. If battery voltage is as specified, check module ground circuit. With TFI module disconnected and KOEO, measure voltage at terminal No. 6. If voltage is greater than.5 volt, ground circuit has high resistance or is open. Repair as necessary.
4. Ensure ignition is off. Disconnect distributor connector. Turn ignition on. With DVOM set on DC voltage scale, connect positive (+) lead to terminal No. 8 (terminal No. 4 on 3.0L Aerostar and Ranger). Connect negative (-) lead to distributor or engine ground. (Scheme 65)
5. Cycle ignition switch between ON and START positions. Battery voltage should be present in both positions. If not, service or repair circuit as necessary. If okay, go to next step.
6. Using a DVOM, check ignition ground circuits continuity. Measure resistance between distributor base and terminals No. 2 and No. 6 at distributor connector (terminal No. 3 on 3.0L Aerostar and Ranger).If resistance at each terminal is less than 3 ohms, circuit is okay. If resistance is 3 ohms or greater, repair ground circuit as necessary. (Scheme 66)

Scheme 66

TFI Module Resistance Test

1. Remove TFI module from distributor or disconnect cowl. Measure resistance of TFI module circuits. See «TFI MODULE RESISTANCE»(/ford/explorer/i-1990-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-gasoline). (Scheme 64)- (Scheme 66).
2. If resistance is as specified, suspect faulty PIP sensor/stator. If resistance is NOT as specified, replace TFI-IV module.

TFI MODULE RESISTANCE

PIP Sensor/Stator Test (Except Closed Bowl Distributor)

1. Ensure TFI module mounting screws are tight on distributor. Turn ignition off. Remove coil wire at distributor cap and ground end of coil wire. Ensure coil wire does not break contact with ground during this test.
2. Disconnect SPOUT connector located near distributor. Connect positive (+) lead of DVOM to TFI module side of SPOUT connector and negative lead to distributor base.
3. Turn ignition switch on and bump starter to rotate engine a small amount. Measure and record voltage (allow DVOM voltage reading to stabilize). Repeat procedure 10 times. Voltage should vary as hall sensor vanes and windows rotate through PIP sensor.
4. Voltage reading should vary between .5 volt and 11.5 volts (90% of battery voltage). If the higher voltage readings are only about 70% of battery voltage, go to TFI MODULE RESISTANCE TEST. If TFI module resistance is greater than specified, replace TFI module. If resistance is less than specified, replace PIP sensor.
5. If the lower voltage readings are greater than .5 volt and ignition module resistance is within specification, replace PIP sensor. If PIP sensor and module test okay, go to next step to check for PIP signal at ECA during cranking.
6. Turn ignition off and install Break Out Box (BOB) at ECA connector. Connect a DVOM between test terminals No. 56 (PIP) and No. 16 (IGN GND). Measure PIP signal voltage while cranking engine. Voltage should vary between 4 and 6 volts. If not, check for an open or grounded PIP circuit or an open IGN GND circuit at test terminal No. 16. Repair circuits as necessary. If circuits are okay, but PIP signal is erratic or not present, go to next step.
7. With ECA and TFI module disconnected, connect DVOM positive (+) lead to PIP circuit at harness connector and ensure circuit is not shorted to power during engine cranking. If circuit is okay, replace TFI module and retest system.

PIP Sensor/Stator Test (Closed Bowl Distributor)

1. With ignition off, ensure distributor is connected to vehicle harness. Disconnect vehicle harness connector at TFI module. Connect DVOM positive (+) lead to terminal No. 6 at TFI vehicle harness connector. Connect negative (-) lead to ground. (Scheme 65)
2. Crank engine and measure DC voltage. Voltage should vary between 4 and 6 volts. If voltage varies, refer to SPARK TIMING ADVANCE TEST. If voltage does not vary, go to next step.
3. With ignition off, disconnect distributor connector. Using DVOM, measure resistance between terminals No. 1 and No. 5 at distributor connector. If resistance is 200 ohms or more, replace faulty PIP sensor. (Scheme 66)
4. Disconnect vehicle harness connector at TFI module. Measure resistance between terminal No. 6 (PIP) at TFI module vehicle harness connector and terminal No. 5 (PIP to TFI Module) at distributor vehicle harness connector. (Scheme 65) If resistance is 5 ohms or more, repair open in circuit and retest. Check circuit for short to ground. Test circuit for short to power with KOEO. Service or replace wiring as necessary.
5. Disconnect ECA connector and measure resistance between terminal No. 56 (PIP) at ECA 60-pin connector and terminal No. 1 (PIP to ECA Module) at distributor vehicle harness connector. If resistance is 5 ohms or more, repair open in circuit and retest. Check circuit for short to ground. Test circuit for short to power with KOEO. Service or replace wiring as necessary.
6. Measure resistance between distributor connector terminal No. 2 (PIP Sensor Ground) and ground. Measure resistance between IGN GND, distributor connector terminal No. 6 (terminal No. 3 on 3.0L Aerostar or Ranger) and ground. If resistance is less than one ohm in both cases, ground circuit is okay. If resistance is one ohm or more in both cases, check PIP sensor mounting screws in distributor base for corrosion and tightness.

Coil Test

1. Connect negative (-) DVOM lead to distributor base and measure battery voltage. Turn ignition switch to RUN position. Measure voltage at coil positive (+) terminal and turn ignition off. Voltage should be 10.5-12 volts. If voltage is as specified, go to next step. If voltage is not as specified, repair or replace ignition switch or wiring circuit to coil. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.
2. Ensure ignition is off. Disconnect coil primary connector and inspect both contacts for corrosion or damage. Service or replace as necessary. Using a DVOM, measure primary circuit resistance. If resistance is not .3-1.0 ohm at 70°F, replace coil and retest system.
3. Remove secondary coil wire from coil tower and inspect contact for signs of arcing or corrosion. Using a DVOM, measure resistance between coil tower connector and coil negative (-) terminal. If resistance is not 8000-11,500 ohms, replace coil.

Spark Timing Advance Test

1. This procedure is applicable to all TFI-IV equipped vehicles. Spark advance is controlled by ECA. This procedure checks capability of ignition module to receive spark timing commands from ECA on the SPOUT circuit. A varying voltage signal is necessary on SPOUT circuit for ECA to transmit data. A KOER Code 18 or Code 213 may be set when SPOUT circuit is open or shorted. For additional information on TFI ignition systems, see THEORY/OPERATION article in the ENGINE PERFORMANCE Section.
2. Check SPOUT circuit voltage at TFI module. Ensure ignition switch is in OFF position. Disconnect SPOUT in-line connector near TFI module. If connector is SHORTING BAR type, remove SHORTING BAR.
3. Attach negative (-) voltmeter lead to distributor base and positive (+) lead to TFI module side of the SPOUT connector. Start engine and measure voltage at idle. Measure voltage at ECA side of SPOUT connector.
4. Voltage readings should be 4-8 volts. If voltage on TFI module side is okay, TFI module is okay. This voltage signal is necessary for TFI module to receive ECA SPOUT signal. If voltage signal from ECA to SPOUT connector is as specified, circuit from ECA to SPOUT connector is okay. If either voltage signal is not as specified, go to next test. If both voltage signals are as specified, check ignition timing advance.
5. Check SPOUT circuit continuity. Push TFI module connector tab to release connector. Separate wiring harness connector from ignition module. Inspect for dirt, corrosion and damage.
6. Using a small straight pin inserted into harness connector terminal No. 5, measure resistance between terminal and TFI module side of SPOUT connector. Resistance should be less than 5 ohms. If resistance is 5 ohms or more, repair wiring as necessary.
7. Measure resistance between ECA side of SPOUT connector and pin No. 36 at ECA connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair wiring between SPOUT connector and ECA.
8. Check Ignition Timing Advance. With SPOUT connector disconnected, run engine at idle and ensure timing is at base timing adjustment. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section. Stop engine.
9. Connect SPOUT connector and start engine. Timing should advance from base timing specification. Increase engine RPM and ensure timing advances. If time does not advance, check TFI module. If module is okay, replace ECA.

Scheme 67

Scheme 68

DIS SYSTEM

Note. Start all diagnostics with EEC-IV Quick Test. See TESTS W/CODES article in the ENGINE PERFORMANCE Section. These tests are dependent on results and service codes received during Quick Test procedures.

Ensure following preliminary checks have been performed

1. Visually inspect engine compartment to ensure all vacuum hoses and spark plug wires are properly and securely connected.
2. Check all wiring harnesses and connectors for damaged insulation, burned, overheating, damaged pins, loose or broken conditions. Check sensor shield connector. Ensure DIS module mounting screws are tight.
3. Ensure battery is fully charged.
4. Turn all accessories off during diagnosis.

Following test equipment is necessary to complete DIS ignition system tests.

1. DIS Diagnostic Cable (Rotunda 007-00044)
2. Spark Tester (Neon Bulb Type)
3. Digital Volt-Ohmmeter (DVOM)
4. Remote Starter Switch
5. Breakout Box (BOB) With 2.3L DP DIS Overlay
6. High Voltage Spark Tester (A spark plug with a broken side electrode is not sufficient to check for spark and may lead to incorrect results.)
7. Tachometer
8. Inductive Type Timing Light (DO NOT use "advance knob", if equipped, as it will not work correctly with DIS Ignition Systems.)
9. Test Light (LED Type) Or Logic Probe (LED Type)

PINPOINT TESTS A through F are intended to diagnose hard faults. Intermittent failures may be difficult to diagnose using these procedures.

A Breakout Box (BOB) connected to DIS diagnostic cable is referred to as DIS BOB. If a second BOB is connected to the ECA vehicle harness connector it is referred to as ECA BOB. This test setup allows testing of DIS components and vehicle harness circuits.

Circuits are identified in all capitals, example: IGND = Ignition Ground. Manufacturers BOB overlay identification is in brackets, example: (J2) = IGND (J2). This indicates test terminal number or circuit identification number.

Note. Unless specified otherwise in a specific test step, all voltage and resistance tests of DIS ignition system are performed at the BOB connected to the DIS diagnostic cable.

Note. When performing PINPOINT TEST procedures for the 2.3L DIS (Ranger) system (Scheme 69)and (Scheme 70).

Scheme 69

Scheme 70

2.3L RANGER DIS PINPOINT TEST INDEX

PINPOINT TEST A

PINPOINT TEST B

PINPOINT TEST C

PINPOINT TEST D

PINPOINT TEST E

PINPOINT TEST F

EDIS SYSTEM

Note. Start all diagnostics with charts in TESTS W/CODES article in the ENGINE PERFORMANCE Section. Perform Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section before entering this test. These tests are dependent on results of Quick Test procedure.

Note. The EDIS Diagnostic Cable (Rotunda 007-00059) should be used to diagnose this system. This cable is equipped with additional resistors, circuits and components used to enhance and modify signals for testing purposes. If an aftermarket test cable is used, or diagnosis is being performed using only a DVOM, ensure technician is familiar with system wiring diagram and system operation.

Preliminary Checkout

Visually inspect engine compartment to ensure all vacuum hoses and spark plug wires are properly and securely connected. Examine all wiring harnesses and connectors for damaged insulation, burned, overheated, damaged pins, loose or broken conditions. Check sensor shield connector. Ensure EDIS module mounting screw is tight. Ensure battery is fully charged and all accessories are off during diagnosis.

Following test equipment or equivalent should be used in these test procedures.

1. EDIS Diagnostic Cable (Rotunda 007-00059)
2. Spark Tester (Neon Bulb Type)
3. Volt-Ohmmeter (Rotunda 007-00001)
4. Remote Starter Switch
5. 2 Breakout Boxes (BOB), For DIS (DIS BOB) And ECA (ECA BOB)
6. Spark Tester (D81P-6666-A Or equivalent)
7. Inductive Timing Light
8. Test Light (LED Type) Or Logic Probe (LED Type)

When making measurements on a wiring harness, both a visual inspection and a continuity test should be performed. Inspect terminal connector pins for damage and corrosion, when directed to remove a connector.

1. Spark timing adjustments are not possible. Timing is controlled by the EDIS module with input from the ECA.
2. When checking voltage drop to GROUND, circuit must have a voltage drop of less than one volt.
3. Battery voltage (VBAT) is any voltage reading within 2 volts of actual battery voltage.
4. Spark timing will vary at idle due to feedback spark strategy used to control idle speed.
5. DO NOT connect positive lead of EDIS diagnostic cable to battery or connect cable to VR sensor until directed to.
6. SAW and IDM signal detectors in EDIS diagnostic cable will not work unless diagnostic cable battery leads are connected to battery.
7. When using DVOM to measure DC voltage always connect positive lead to BOB terminal A (+) and negative lead to A (-).

Note. When using PINPOINT TEST procedures for the 4.0L EDIS (Aerostar, Explorer & Ranger) system (Scheme 72)& (Scheme 73).

Scheme 71

Scheme 72

4.0L EDIS PINPOINT TEST INDEX

Air Supply Pump

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

Air Silencer/Filter (Air Pump & Pulse Air Inlet)

Inspect hoses and air silencer for leaks. Disconnect hose from air silencer outlet. Remove silencer from vehicle, and visually inspect for plugging. If no plugging or leaks are found, silencer is okay. If any plugging or leaks are found, repair or replace as required.

Scheme 73

1. Disconnect air supply hose at valve outlet. (Scheme 74) Remove vacuum line from vacuum nipple and check for presence of vacuum at nipple. There must be vacuum present at nipple before proceeding.
2. Reconnect vacuum line to vacuum nipple. With engine at 1500 RPM, air pump supply air should be heard and felt at air by-pass valve outlet.
3. With engine still at 1500 RPM, disconnect vacuum line. Air at outlet should decrease significantly or shut off. Air pump supply air should now be heard or felt at silencer ports or at dump port.
4. If the normally closed air by-pass valve does not perform as described in steps 2) and 3), check the air pump for faults. If air pump is operating satisfactorily, replace air by-pass valve.

Air Check Valve

1. Visually inspect thermactor hoses, tubes, control valve(s) and check valve(s) for leaks that may be due to backflow of exhaust gases. If holes are found and/or traces of exhaust gas products are evident, check valve may be suspect.
2. Valve should allow free flow of air in direction of arrow only. (Scheme 75) The valve(s) should check (or block) the free flow of exhaust gas air in the opposite direction.
3. If air does not flow as indicated or if exhaust gas backflows opposite of direction of arrow in illustration, replace check valve.

Scheme 74

Scheme 75

1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Disconnect air supply hoses at outlets "A" and "B". (Scheme 76) Remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air supply control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
4. If valve does not operate as specified, replace valve. If airflow operates as described in steps 1), 2) and 3), valve is okay. Reinstall hoses and clamps.

Scheme 76

1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Carefully disconnect the air supply hoses at outlets "A" and "B". (Scheme 77) Carefully remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
4. If conditions in steps 2) and 3) are not as specified, replace air control valve. If the valve operates satisfactorily, restore all hose and vacuum connections.

Air Pump Resonator

Visually inspect for holes. Remove hoses and check for restricted ports. Replace resonator if holes or ports are restricted. Reconnect hoses and install clamps.

Scheme 77

1. Disconnect hoses from outlets "A" and "B". (Scheme 78) Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should be flowing from by-pass vents.
2. Reconnect vacuum line to port "D". Disconnect and plug vacuum line to port "S". Ensure vacuum is present in line to vacuum port "D". Accelerate engine to 1500 RPM. Airflow should be noted coming out of outlet "B". No airflow should be detected at outlet "A".
3. Apply 8-10 in. Hg vacuum to port "S". With engine operating at 1500 RPM, airflow should be noted coming out of outlet "A". If valve is bleed type, less air will flow from outlet "A" or "B", and the main discharge will change when vacuum is applied to port "S".
4. If the conditions in the above steps are not met, replace valve. If above conditions are met, valve is okay. Reconnect hoses and vacuum lines.

Dual Thermactor Air Control Solenoid Valve

Function of each valve can be determined by externally energizing valve with vacuum lines attached. Check resistance of each solenoid. Resistance should be 51-108 ohms when checked at coil terminals. If resistance is not 51-108 ohms, solenoid should be replaced.

Thermactor Idle Vacuum (TIV) Valve

1. With engine at idle and transmission in Neutral, apply vacuum to small nipple and place fingers over the TIV valve atmospheric vent holes. (Scheme 79) If no vacuum is sensed, the TIV is damaged and must be replaced. If vacuum is sensed, go to next step.
2. With engine still at idle, apply vacuum to TIV valve large nipple using a vacuum pump. See «TIV VALVE (LARGE NIPPLE) VACUUM SPECIFICATIONS»(/ford/explorer/i-1990-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-gasoline). If vacuum is not held, the TIV is damaged and must be replaced. If no vacuum is sensed, replace valve.

Scheme 78

TIV VALVE (LARGE NIPPLE) VACUUM SPECIFICATIONS

Scheme 79

1. A 2-port valve may be in open or closed position when engine is cold, but should reverse when engine is warmed to operating temperature.
2. For 3-port valves, with a cold engine, passage "A" to "B" should be closed and passage "A" to "C" should be open. (Scheme 80) With engine at normal operating temperature, the VCV should be open between "A" and "B" and closed between "A" and "C".
3. For the 4-port valve, check "A1" to "B1" and "A2" to "B2" separately. (Scheme 80) A 4-port valve may be in open or closed position when engine is cold, but should reverse when engine is warmed to operating temperature. If valve does not operate as specified, replace the valve.

Scheme 80

1. Electrical vacuum control valve may be either open or closed at room temperature, but should reverse the position when engine is at full operating temperature. While engine is cold, measure continuity across switch terminals. see scheme 28 Note if switch is open or closed.
2. Warm engine to normal operating temperature. Measure continuity across switch terminals again. Continuity should be opposite of cold condition. If switch continuity does not switch, replace valve. Check vacuum function of valve as described in VACUUM CONTROL VALVE.

Vacuum Check Valve

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If vacuum drops faster, replace valve.

Vacuum Reservoir

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed .5 in. Hg in 60 seconds. If vacuum loss is faster, replace reservoir.

Pulse Air Valve

With engine at normal operating temperature and at curb idle, remove inlet hose from valve. A suction should be felt at valve inlet. If suction is not felt, replace valve.

Electronic EGR Valve (EEGR) & Pressure Feedback Electronic (PFE)

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than one in. Hg vacuum to EGR valve at idle with engine at normal operating temperature. NOTE: EVR solenoid has a constant internal leak. You will notice a small vacuum signal of less than one in. Hg vacuum at idle.
2. Install tachometer. Disconnect Idle Air By-Pass Valve electrical connector (if equipped). Remove and plug vacuum hose at EGR valve. Start engine and idle in neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg vacuum to EGR valve. When vacuum is fully applied to EGR valve, engine should do one or more of the following: Engine should stall. Idle speed should drop more than 100 RPM. Idle speed should return to normal when vacuum is released.
3. Repair or replace EGR system if none of the above occurs. Reconnect idle air by-pass valve electrical connector. Unplug and reconnect vacuum hose at EGR valve.

EGR Vacuum Regulator (EVR)

Faults in EVR or circuit should set a service code. See QUICK TEST procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST DN in TESTS W/CODES article in the ENGINE PERFORMANCE Section for diagnostic procedures.

On 2.3L Ranger (1989-92), intermittent operation or failure of EVR may be caused by water in EVR or vacuum hoses connected to it. If water or moisture is found in EVR or hoses connected to it, install new service part, available from manufacturer, in an inverted position. Use shop air to clear water and moisture from vacuum hoses. Clear Continuous Memory Codes if set and run Quick Test to verify repair.

Remove EGR solenoid harness connector. Measure resistance across solenoid terminals. Resistance should be 65-110 ohms. Set DVOM to 200 k/ohm scale. Measure resistance between each solenoid terminal and ground or side of solenoid. Resistance should be 10 k/ohms or more. If resistance is not as specified in either test, replace solenoid.

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If vacuum does not remain greater than 15 in. Hg for 10 seconds, replace valve.

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed .5 in. Hg in 60 seconds. If vacuum loss is greater than specified, replace reservoir.

Canister Purge Regulator (CPR) Valve

With CPR valve de-energized, apply 5 in. Hg vacuum to source port. Valve should not pass air. Apply 9-14 volts to one electrical terminal and ground the other. Valve should open and pass air. If valve does not operate as described, replace valve.

1. Disconnect CANP solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance across CANP solenoid terminals. Resistance should be 40-90 ohms. If resistance is not as specified, replace CANP solenoid.
2. Disconnect vacuum hose at CANP solenoid on manifold vacuum side. Apply 16 in. Hg vacuum to manifold vacuum side of solenoid. CANP solenoid should hold vacuum for 20 seconds.
3. Faults in CANP solenoid or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no service code has been set, see CIRCUIT TEST KD in TESTS W/CODES article in the ENGINE PERFORMANCE Section for additional solenoid and circuit testing.

EVAP Canister

There are no moving parts in canister. Check for loose, missing, cracked or broken connections or parts. Repair or replace as necessary. There should be no liquid in canister.

PCV Valve

1. Remove PCV valve from rocker cover grommet. Shake valve. Valve should rattle when shaken. If valve does not rattle, replace valve.
2. Start engine and warm to normal operating temperature. On 2.3L, 2.9L and 4.9L engines, remove corrugated hose from oil separator nipple. Place stiff piece of paper over nipple end and wait 60 seconds.
3. On all other engines, disconnect hose from remote air cleaner or outlet tube. Place stiff piece of paper over hose end and wait 60 seconds. Vacuum should hold paper in place. If vacuum does not hold paper in place, replace valve.

Air Cleaner Temperature Sensor

Bring temperature of sensor to less than 75°F (24°C), and apply 8 in. Hg vacuum to source port. Duct door should close. If door does not close, replace sensor. Sensor will bleed off vacuum to allow duct door to open and let in fresh air at specific temperatures. See AIR CLEANER TEMPERATURE SENSOR OPENING .

AIR CLEANER TEMPERATURE SENSOR OPENING

Air Control Door

When a vacuum of 8 in. Hg or more is applied to vacuum motor, door should stay in proper position for as long as vacuum is applied. If vacuum bleeds off and door returns to rest position, replace vacuum motor.

See also:
• FUEL PRESSURE SPECIFICATIONS
• FUEL EVAPORATION
• FUEL SYSTEM PRESSURE RELEASE