System/component Tests - Efi Ford Festiva I

INTRODUCTION

Prior to testing separate components or systems, it is highly recommended that all procedures listed in BASIC TESTING article be performed. Since many computer controlled and monitored components will set a trouble code if they malfunction, it is also recommended that self-diagnosis be performed. See TESTS W/CODES article.

Note. Testing of individual components does not isolate possible shorts or opens in the control harness of electronically controlled systems. Use an ohmmeter to isolate shorts or opens in harness.

AIRFLOW METER

Inspect airflow meter for damage and ensure measuring plate moves smoothly. (Scheme 48) Disconnect airflow meter connector. Measure resistance using AIRFLOW METER TERMINAL RESISTANCE.

AIRFLOW METER TERMINAL RESISTANCE

Scheme 48

Brake Light Switch

Disconnect brake light switch connector. Measure resistance between terminals of brake light switch. With brake pedal released, resistance should be infinite. With brake pedal depressed, resistance should be zero ohms.

Clutch Switch

Remove connector from switch. Connect ohmmeter to switch terminals. Check that continuity exists with clutch pedal depressed and no continuity exists with pedal released. Replace switch if continuity is not correct.

Coolant Temperature Sensor

1. Remove coolant temperature sensor. Place coolant temperature sensor in container of heated coolant with thermometer.
2. Connect ohmmeter to coolant temperature sensor terminals. Note resistance at specified temperatures. See «COOLANT TEMPERATURE SENSOR RESISTANCE»(/ford/festiva/i-1986-1993/remont/testing-diagnostics/#systemcomponent-tests-efi) . Replace if not within specification.

COOLANT TEMPERATURE SENSOR RESISTANCE

Coolant Temperature Switch

1. Remove switch from radiator. Place switch in container of heated coolant with thermometer.
2. Connect ohmmeter to switch terminals. Note temperature at which continuity exists between switch terminals. Continuity should exist with coolant temperature above 63°F (17°C). Replace switch if not within specification.

Inhibitor Switch (A/T)

Remove connector from switch. Connect ohmmeter to appropriate switch terminals. See WIRING DIAGRAMS article for wire identification. Continuity should exist with gearshift in Park and Neutral. No continuity should exist in other ranges.

Neutral Switch (M/T)

1. Disconnect connector near transmission. Place transmission in Neutral position. Resistance across switch should be infinite.
2. Place transmission in any gear. Resistance across switch should be zero ohms. If necessary, replace switch.

Oxygen (O2) Sensor

1. Warm engine to operating temperature. Run engine at fast idle. Disconnect O2 sensor. Connect a high impedance voltmeter between O2 sensor and ground.
2. Observe voltmeter while rapidly accelerating and decelerating engine speed. If voltage is not .5-1.0 volt while accelerating and 0-.4 volt while decelerating, replace O2 sensor. Ensure new oxygen sensor has anti-seize compound applied to threads. Tighten sensor to 22-36 ft. lbs. (29-49 N.m).

Power Steering Switch

1. Start engine and allow to idle. Remove connector from switch. Connect ohmmeter to switch terminals. Turn steering wheel from side to side and note continuity reading.
2. Continuity should exist with front wheels turned but should not exist with wheels straight ahead. Replace switch if continuity is not correct.

Pulsation Damper

Start engine and run at idle. Pulsation damper is located at end of fuel rail. Place finger over pulsation damper and ensure damper pulsates. Replace pulsation damper if no operation exists.

Stoplight Switch

Stoplight switch is located at top of brake pedal. Switch should show continuity when brake pedal is depressed.

Throttle Position Sensor

See ADJUSTMENTS article for checking and adjustment procedures.

Vehicle Speed Sensor

See J - PIN VOLTAGES CHARTS and K - SENSOR RANGES CHARTS article.

Operation

The A/C clutch relay is opened (disengages A/C clutch), for 7 seconds during the following conditions: blower and A/C switch on, transmission in gear, clutch pedal released and throttle opened more than half way.

Testing

1. Turn A/C, blower and ignition switches on. DO NOT start engine. Shift transmission into a drive gear. Open throttle fully. Listen for A/C clutch disengaging and reengaging after 7 seconds.
2. If system does not test as indicated, check operations of related switches and relays. See PIN VOLTAGE CHART S and SENSOR RANGE CHARTS .

CIRCUIT OPENING RELAY

See FUEL CONTROL CIRCUIT in BASIC TESTING article for test procedures.

Using stethoscope, listen for normal "clicking" sound at each injector during idle and acceleration.

Injector Resistance

Remove electrical connector from injector. Using ohmmeter, measure resistance between injector terminals. Replace injector if resistance is not within specifications.

FUEL INJECTOR RESISTANCE

PURGE CONTROL SOLENOIDS

For testing procedures, see EVAPORATION CONTROL under EMISSION SYSTEMS and SUB-SYSTEMS.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING .

Fuel Pump Relay Control

See FUEL SYSTEM in BASIC TESTING article.

BPA Valve

1. Remove BPA valve hose from throttle body. (Scheme 49) Blow air through port "A". Ensure air flows when valve is cold. If not, replace BPA valve.
2. Measure resistance of Idle Speed Control (ISC) Valve at 2 wire connector of BPA valve. Resistance should be between 5-20 ohms, at normal operating temperature. If not, replace BPA valve.

Scheme 49

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING .

EMISSION SYSTEMS & SUB-SYSTEMS

Note. For complete vacuum schematics, see VACUUM DIAGRAMS .

System Inspection

1. Start and warm engine to normal operating temperature. With engine idling, connect voltmeter to No. 1 3-way solenoid valve (Black/Yellow terminal). Voltage reading should be about 12 volts. If not, check solenoid and wiring to ECU.
2. Disconnect top hose from No. 1 purge control valve on charcoal canister. Place finger over open end of hose. Increase engine speed to 2000 RPM. Ensure vacuum is not created at hose. If vacuum is present, check No. 1 3-way solenoid valve and wiring to control unit. Remove finger from hose. Leave hose disconnected. Return engine to idle.
3. Disconnect neutral/safety switch connector on manual transaxle, or inhibitor switch connector on automatic transaxle. Voltage reading should be 1.5 volts.
4. Place finger over purge control valve hose. Increase engine speed to 2000 RPM. Vacuum should be created at hose end. If not, check No. 1 3-way solenoid valve and wiring to ECU.

Evaporation Line

Disconnect hose leading from charcoal canister to fuel tank. Connect a vacuum pump to the hose. Apply vacuum and note if vacuum is held. No vacuum should be held. If vacuum is held, test check and cut-valve and evaporation hose for blockage.

Scheme 50

Scheme 51

1. To check No. 1 purge control valve, remove hoses from charcoal canister. Attempt to blow through intake manifold port. Air should not pass. Attach vacuum pump to top port of purge control valve. Apply 4.3 in. Hg. Blow through intake manifold port. Air should flow through port. (Scheme 50) If not, replace valve.
2. The No. 2 purge control valve is an integral part of charcoal canister. Disconnect canister evaporation hose at line leading to fuel tank. Air should pass through valve under pressure and under vacuum, if valve is operating properly. (Scheme 51)
3. To test No. 3 purge control valve, disconnect hoses. Remove No. 3 purge control valve from vehicle. Connect vacuum pump/gauge to single port. Blow into port "A". Ensure air does not flow from port "B". (Scheme 52)
4. Apply about 4 in. Hg to port. Blow into port "A". Air should flow through port "B". If air does not flow, replace purge control valve.

Scheme 52

Purge Solenoid

1. Disconnect vacuum hose from solenoid. (Scheme 53) Blow through port "A". Ensure air exhausts through air filter.
2. Disconnect 2-wire connector from solenoid. Connect 12 volts to one terminal and ground the other terminal of solenoid. Blow air though port "A". Ensure air exhausts through port "B".

Scheme 53

3-Way Valve

Remove 3-way valve. Blow through valve from fuel tank port. Make sure air comes out of canister port. Block canister port. Air should exit vent port. Block canister port. Blow through vent port. If air exits fuel tank port, valve is functioning properly. (Scheme 54)

Scheme 54

PCV

Warm engine to normal operating temperature. Run engine at idle. Disconnect PCV valve together with ventilation hose from cylinder head cover. Block PCV valve opening with a finger and verify engine speed drops.

DECELERATION CONTROL SYSTEM

Deceleration control system is a function of ECU. It provides fuel cut during deceleration.

1. Using analog voltmeter, backprobe ECU connector terminals No. 3C or 3E. Start engine. Voltage should pulsate.
2. Increase engine speed to 4000 RPM. Suddenly decrease engine speed. Voltage should become constant during deceleration. If not, check idle switch, coolant temperature switch and all ECU connections.

HIGH ALTITUDE COMPENSATION SYSTEM

High altitude compensation is a function of ECU. It provides timing advance according to altitude.

1. With engine warm, connect timing light to No. 1 cylinder. Check ignition timing. Timing at less than 3000 feet should be 7 degrees BTDC.
2. Connect vacuum pump to atmospheric pressure sensor. Apply vacuum and check ignition timing. Timing should advance to 13 degrees BTDC.
3. If not, inspect atmospheric pressure sensor and ECU. Ensure altitude is not greater than 3000 feet.

See also:
• AIRFLOW METER TERMINAL RESISTANCE