System/component Tests - Carbureted 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.

Scheme 34

BAROMETRIC PRESSURE SWITCH CIRCUIT TEST

1. Check for loose connectors, corrosion or damage at BP switch and ECA terminal 2H. Repair as necessary.
2. Check continuity across BP switch. Continuity across switch should exist when 0-27.2 in. Hg is applied to switch. With 27.3-30 in. Hg applied to BP switch, there should be no continuity. If continuity readings are incorrect, replace switch.
3. With 27.3-30 in. Hg applied to BP switch, check voltage at ECA terminal 2H. Voltage should read 0-2.5 volts. Release vacuum and voltage should increase to 12-14 volts. If voltage readings are not to specification, check for opens or shorts in wiring between BP switch Blue/Orange wire terminal and ECA terminal 2H. Repair as necessary.

Clutch Switch (M/T)

Disconnect clutch switch connector and check continuity between switch terminals. (Scheme 34) Depress clutch pedal and verify continuity is present. Release clutch pedal and verify no continuity is present.

Clutch & Neutral Switches Circuit Test

1. Check for continuity across clutch switch. Continuity should exist only when clutch is depressed.
2. Check for continuity across neutral switch. Continuity should exist only when vehicle is in Neutral. If continuity readings are not correct, replace defective switch.
3. Check continuity between Black wire terminal of clutch and ground. Repeat check with neutral switch. If continuity does not exist, repair ground circuit(s).
4. Check for voltage at ECA terminal 1G. Voltage should read 12-14 volts when clutch pedal is released or vehicle is in any gear except Neutral. When clutch is depressed or transmission is in Neutral, voltage should read 0-2.5 volts. If voltage readings are not correct, check for opens or shorts in wiring between clutch and neutral switch Blue/White wire terminals and ECA terminal 1G. Repair as necessary.

Coolant Temperature Switch

1. Allow engine to cool completely and remove radiator cap. Place thermometer in radiator (below coolant level). Measure resistance between switch terminal and ground. Resistance should be 10,000 ohms or greater.
2. Start engine and run until temperature exceeds 207°F (97°C). Switch should open when coolant temperature reaches 207°F (97°C) and close when coolant temperature drops below 194°F (90°C). Resistance of switch when open should be 0-5 ohms. Replace coolant temperature switch if resistance is not as specified.

Coolant Temperature Sensor

1. Warm engine to operating temperature and run at idle speed. Remove rubber boot from coolant temperature sensor connector. (Scheme 34) Turn ignition switch on. Verify voltage between Blue/Red terminal and ground is 0.5 volts. If not, check resistance of sensor and wiring harness for an open or short circuit.
2. Remove coolant temperature sensor and place in water with a thermometer. Heat water gradually. Verify resistance of sensor is to specifications. See «COOLANT TEMPERATURE SENSOR RESISTANCE»(/ford/festiva/i-1986-1993/remont/testing-diagnostics/#systemcomponent-tests-carbureted).

COOLANT TEMPERATURE SENSOR RESISTANCE

Coolant Temperature Switch Circuit Test

1. Check continuity across coolant temperature switch (mounted in radiator). With engine cold, continuity should exist. With radiator temperature above 62.6°F (17°C), switch should open (no continuity). If switch continuity is incorrect, replace switch.
2. Check continuity between switch Black wire terminal and ground. If continuity does not exist, repair switch ground circuit.
3. Check voltage at ECA terminal 1L. With engine cold, voltage should read 12-14 volts. With engine warm, voltage should read 0-2.5 volts. If voltage readings are incorrect, check for opens or shorts in wiring between Light Green wire terminal and ECA terminal 1L. Repair as necessary.

ECA ELECTRICAL SWITCH INPUTS

Check switch input voltages at ECA. If voltage readings are incorrect, check for opens, shorts or bad connections in wiring between switches and ECA. Repair as necessary. If all harnesses are okay, replace ECA.

ECA ELECTRICAL SWITCH VOLTAGE INPUTS

ECA Ground Circuit Test

1. Check for continuity between ECA terminal 3G and ground. Check continuity between ECA terminal 3A and ground. If continuity does not exist, check wiring from ECA terminals 3A and 3G to ground.
2. Check ECA terminals 3A and 3G for zero volts. If voltage is present, replace ECA.

ECA Keep Alive Power Circuit Test

1. With key off, check for 12 volts at ECA terminal 3J. If battery voltage is not present, check for open or short in wiring between battery positive terminal and ECA terminal 3J. Repair as necessary.
2. With key on, check for 12 volts at ECA terminal 3J. If 12 volts is not present, check ignition switch for proper operation. Repair or replace as necessary.

ECA Key On Power Circuit Test

1. With key on, check for 12 volts at ECA terminal 3I. If voltage is not present, check for opens or shorts in wiring between ignition switch and ECA. Repair as necessary.
2. With ignition switch in "START" position, check for 12 volts at ECA terminal 3I. If 12 volts is not present, check ignition switch for proper operation. Repair or replace as necessary.

IDLE SWITCH

Disconnect Black/Blue wire from idle switch. Measure resistance between Black/Blue terminal of idle switch and ground. With throttle closed, resistance should be greater than 10,000 ohms. With throttle open, resistance should be less than 5 ohms. If resistance is not as specified, adjust or replace idle switch.

Idle Switch Circuit Test

1. Check continuity across idle switch terminals at idle. Continuity should not exist. Check continuity at 1160 RPM. Continuity should now exist. If continuity does not exist, adjust or replace idle switch as necessary.
2. Check continuity between idle switch Black wire terminal and ground. If continuity does not exist, repair idle switch ground circuit.
3. Check idle switch voltage at ECA terminal 1E. At idle, voltage should read 12-14 volts. At about 2000 RPM, voltage should read 0-2.5 volts. If voltage is not present, check for opens or shorts in wiring between idle switch and ECA. Repair as necessary.

Neutral Switch

Disconnect switch connector. (Scheme 34) Using an ohmmeter, check continuity between switch Blue/Green and Black terminals. With shift lever in Neutral, there must not be continuity. With shift lever in other positions, continuity must be present. Replace defective neutral switch.

O2 Sensor

See FUEL CONTROL in this article for testing procedure.

4Th Gear Switch Circuit Test

1. Check continuity across 4th gear switch terminals. Continuity should exist in 1st, 2nd and 3rd gear. Continuity should not exist in 4th gear. If continuity readings are not correct, replace 4th gear switch.
2. Check continuity between 4th gear switch Black wire terminal and ground. If continuity does not exist, repair 4th gear switch ground circuit.
3. Check for voltage at ECA terminal 1F. Voltage should read 0-2.5 volts when vehicle is in 1st, 2nd or 3rd gear. Voltage should read 12-13 volts when vehicle is in 4th gear. If voltage readings are not within specification, check for opens or shorts in wiring between 4th gear switch Light Green terminal and ECA terminal 1F. Repair as necessary.

AIR INJECTION SOLENOIDS & RELAYS

See EMISSION SYSTEMS & SUB-SYSTEMS in this article.

EGR SOLENOIDS & RELAYS

See EMISSION SYSTEMS & SUB-SYSTEMS in this article.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING article in this section.

Altitude Compensator Testing (Below 3280 Feet)

Remove 3 hoses from HAC valve and note idle quality. Idle quality should be poor due to the introduction of excessive air for low altitude operation. If idle quality remains unchanged, replace HAC valve.

Altitude Compensator Testing (Above 3280 Feet)

Remove and plug 3 hoses from HAC valve and note idle quality. Poor idle quality should result due to insufficient air for high altitude operation. If idle quality remains unchanged, replace HAC valve.

Scheme 35

Feedback Carburetor Actuator (FBCA)

See TESTS W/CODES article for test procedures.

Hot Idle Compensator

1. Attach hose to hot idle compensator nipple at top of air cleaner. Attach vacuum pump with gauge to hose. With vehicle cold, apply 5 in. Hg to hot idle compensator. Valve should be closed.
2. Using heat gun, heat hot idle compensator. Hot idle compensator should open when heated to 114-192°F (45-89°C). If hot idle compensator does not open or if it leaks excessively when cold, replace hot idle compensator.

1. Warm engine to normal operating temperature and allow to idle. Connect voltmeter between O2 sensor connector and ground. (Scheme 34)
2. Run engine at 4000 RPM until voltmeter reads.7 volts. Increase and decrease engine RPM suddenly and several times. When engine RPM is increased, voltmeter should read.5-1.0 volt. When engine RPM is decreased, voltmeter should read 0-.4 volt. Replace defective O2 sensor.

Scheme 36

1. Warm engine and run at normal idle. Observe vacuum servo action while turning on headlights, rear window defroster, heater blower to high and A/C all separately. Vacuum servo should move and hold position when each load switch is turned on.
2. If vacuum servo does not move and hold, remove vacuum hoses from servo. Plug or cap one port on servo. Connect vacuum test pump to other port on servo. Apply a 10 in. Hg steady vacuum and confirm servo moves and holds.
3. Switch vacuum test pump and plug to test other side of servo. If either side fails to move and hold position, replace servo.
4. Disconnect vacuum hoses from load control solenoids. Connect test hose to port "A" and confirm air exits from port "C". Apply battery voltage to Black/White terminal of solenoid and ground Blue/Yellow terminal on A/C load control solenoid and Light Green/Red terminal of electrical load control solenoid. Blow into port "A" and confirm air exits from port "B". If not correct, replace solenoid(s).

Scheme 37

IGNITION SYSTEM

See BASIC TESTING article for testing procedures.

TIMING CONTROL SYSTEM

Ignition timing is controlled by both vacuum and centrifugal advance. See SPECIFICATIONS article for testing procedures.

System Test

Inspect pulse air system vacuum lines, hoses, wiring and electrical components for damage, opens, bad connections and wear. Inspect reed valves and confirm that valves are not leaking exhaust gas into air cleaner assembly. Repair or replace components as necessary.

Scheme 38

Reed Valve Check

1. Start engine and allow it to reach normal operating temperature. Run engine at idle. Remove air cleaner cover and air filter element.
2. Using a small strip of paper over reed valve inlet port in air cleaner housing, confirm that vacuum is present at idle. Paper strip should be sucked into reed valve port and no exhaust gas should flow out of reed port. If not correct, replace reed valve.

Control Valve Vacuum Diaphragm Check

1. With engine warm and idling, disconnect neutral switch.
2. Disconnect vacuum hose from air control valve vacuum diaphragm. Increase engine speed to 1160 RPM. Verify that vacuum signal exists below 1160 RPM. Above 1160 RPM, vacuum signal should bleed off when air control solenoid is de-energized by ECA.
3. Using hand-held vacuum pump, apply vacuum to air control valve diaphragm. (Scheme 39) Valve should open at about 5.5 in. Hg. If valve fails to open, replace vacuum diaphragm.

Scheme 39

Air Control Solenoid Valve

1. With engine warm and idling, disconnect neutral switch.
2. Check voltage on air control solenoid valve Yellow/Blue wire terminal. Below 1160 RPM, reading should be 0-1.5 volts. Above 2500 RPM, voltmeter should read 12-14 volts. If voltage is not correct at 2500 RPM, check voltage supply from ignition switch to Black/White solenoid wire terminal.
3. Disconnect vacuum hoses from solenoid valve. Blow through port "A" of the solenoid and confirm that air bleeds from port "C" at bottom of valve. see scheme 7
4. Briefly apply battery voltage and ground to solenoid valve terminals. Solenoid should click. Blow through port "A" of the solenoid valve and confirm that air bleeds off from port "B" when solenoid is energized.

Heater Element

Disconnect heater element connector and check for continuity from terminals "Y" to "R" and "Y" to "B". If continuity does not exist, replace heater element.

Heater Relay

1. Locate EFE heater relay under dash, above steering column. Disconnect heater relay 4-wire connector. Remove heater relay if necessary to access terminals.
2. Using an ohmmeter, check continuity across relay terminals No. 3 and 4. Continuity should not exist.
3. Energize relay by supplying battery voltage to relay terminal No. 1 and ground to terminal No. 2. Continuity should now exist between terminals No. 3 and 4. If relay does not function properly, replace relay.

Scheme 40

EGR System

1. Visually inspect all EGR components, vacuum lines and wiring for opens, bad connections or damage. Repair as necessary.
2. Start engine. With engine cold, place finger against EGR valve diaphragm. Increase engine RPM. Diaphragm should not move. If diaphragm moves, inspect No. 1 EGR vacuum solenoid valve and coolant temperature switch for proper operation.
3. After vehicle has reached operating temperature, repeat test. Diaphragm should now move.
4. If diaphragm does not move and no change in engine performance is noted, remove EGR vacuum line and apply 6 in. Hg. If engine runs rough, go to step 6.
5. If RPM does not change and engine does not run roughly or stall, remove EGR valve and inspect EGR passages for carbon build-up. If passageways to intake and exhaust system are clear, replace EGR valve.
6. If engine runs roughly in step 4, inspect vacuum solenoid valves and modulator valve for proper operation.

No. 1 EGR Vacuum Solenoid Valve

1. With engine cold and idling, disconnect vacuum hose from port "A" of solenoid valve and check for vacuum. No vacuum should be felt when engine is cold. If vacuum is felt with engine cold, check coolant temperature switch for proper operation.
2. When engine reaches operating temperature, vacuum should be felt at port "A". If vacuum is not felt with engine warm, check modulator valve for proper operation. (Scheme 41)
3. If No. 1 EGR valve functions properly, check No. 2 EGR vacuum solenoid valve for proper operation.
4. Check voltage at No. 1 EGR valve Brown lead. With engine cold, voltage should read 0-1.5 volts. With engine at operation temperature, voltage should read 12-14 volts. If voltage readings are not correct, check Black/White wire terminal for battery voltage from ignition switch.
5. Disconnect hoses from valve. Place proper size hose on port "A" fitting. Blow into hose. Air should exit from port "C". (Scheme 41)
6. Apply battery voltage and ground to valve electrical terminals. Blow in hose connected to port "A". While solenoid is energized, air should exit from port "B". If valve fails to operate as stated, replace No. 1 vacuum solenoid valve.

Note. For more information on testing No. 1 EGR vacuum solenoid valve, see CODE 28 test procedure in TESTS W/CODES article in this section.

Scheme 41

No. 2 EGR Vacuum Solenoid Valve

1. With engine warm and idling, disconnect vacuum hoses from No. 2 solenoid valve. Disconnect vacuum hose from MAP sensor and plug hose.
2. With a hand-held vacuum pump, apply 10 in. Hg to port "A" of valve. Raise engine speed above 2100 RPM. Check for vacuum at port "B". (Scheme 41)
3. If vacuum is present, proceed to COOLANT TEMPERATURE SWITCH test.
4. If vacuum is not present, check voltage at Brown/White wire terminal of valve. Below 2100 RPM, voltage should read 0-2.5 volts. Above 2100 RPM, voltage should read 12-14 volts. If voltage is not correct, check for battery voltage from ignition to Black/White wire terminal of solenoid. Repair as necessary.
5. Disconnect solenoid electrical connector. Blow into hose installed on port "A" of valve. Air should exit from port "C".
6. Apply battery voltage and ground to No. 2 EGR vacuum valve electrical terminals. Blow into port "A". Air should now exit from port "B". If valve does not react as stated, replace No. 2 EGR vacuum valve.

Note. For more information on testing No. 2 EGR vacuum solenoid valve, see CODE 29 test procedure in TESTS W/CODES article in this section.

Modulator Valve

1. If necessary, remove modulator valve to access all vacuum fittings. Remove all hoses. Plug modulator No. 1 and No. 2 ports. Blow into hose located on bottom exhaust fitting of modulator to close diaphragm bleed. (Scheme 42)
2. With a hand-held vacuum pump, apply 7 in. Hg to port No. 3 of modulator. Vacuum should hold. Release pressure from exhaust fitting hose to open diaphragm bleed. Vacuum on gauge should drop. If valve does not perform as stated, replace modulator valve.

Scheme 42

Delay Valve

1. Connect 39" (one meter) long hose to vacuum signal side of EGR delay valve. Block opposite port with finger.
2. With a hand-held vacuum pump, apply 25 in. Hg to delay valve. Remove finger. Vacuum should take about one second to bleed off. Reverse valve and repeat test. Vacuum should bleed off instantaneously. If there is no delay or valve delays in both directions, replace valve.

1. With engine cold and not running, check continuity across coolant temperature switch (in radiator) terminals. Below 62°F (16.7°C), continuity should exist.
2. Start engine and allow to warm. Above 62°F (16.7°C), continuity across switch terminals should not exist.
3. If continuity readings are incorrect, replace coolant temperature switch.

Scheme 43

1. Start engine and run until it reaches normal operating temperature. Check canister for cracks, damage, leakage or saturation. If any of these conditions exist, replace canister.
2. Remove canister from vehicle. Check function of No. 1 (uppermost) purge control valve. Attach vacuum pump with gauge to hose attached to No. 1 purge control valve nipple.
3. Apply vacuum to No. 1 purge control valve. Blow into port on side of canister. (Scheme 43) Valve should be closed when vacuum is below 4.4 in. Hg and should open when vacuum is above 4.4 in. Hg.
4. If purge control valve does not function, replace carbon canister/purge control valve assembly. Check function of No. 2 (on top of canister opposite No. 1 purge control valve) purge control valve. (Scheme 43)
5. Attach hose to No. 2 purge control valve nipple. Alternately blow and suck on hose. Air should pass freely in both directions. If purge control valve does not function, replace carbon canister/purge control valve assembly.

Fuel/Vapor Separator

Visually inspect separator for cracks or damage. If cracked or damaged, replace separator.

Purge Control Solenoid Valve

1. Disconnect fuel vapor hose from solenoid valve. Attach a test hose in it's place. Blow into test hose while turning ignition on and off.
2. Air should pass into canister when ignition is on. Valve should seal tight with ignition turned off. If not, check for 12 volts from ignition switch.
3. If 12 volts are present and valve still does not function, replace carbon canister/purge control valve assembly.

Rollover Check Valve

Remove rollover check valve from vehicle. Blow into port "A". Air should flow out of port "B". Cover port "B". Blow into port "A". Air should flow through port "C". (Scheme 44) If not, replace valve.

Scheme 44

Vacuum Switch Valve

1. Remove Vacuum Switch Valve (VSV) from vehicle. Apply vacuum to the diaphragm nipple. Blow through either port "A" or "B". (Scheme 45)
2. VSV should be closed when vacuum is below 2.6 in. Hg and open when vacuum is above 4.2 in. Hg. If the VSV does not function, replace valve.

Scheme 45

Coolant Thermovalve

Disconnect coolant thermovalve hose from No. 1 purge control valve nipple. With engine cold, blow into hose. Valve should be closed. Start engine and let idle. Valve should open when temperature reaches 131°F (55°C) or before engine is completely warmed. If thermovalve does not function, replace valve.

Scheme 46

PCV Valve

1. Inspect PCV system for air leaks or flow restrictions. Check grommet and hose for splits and cracks. Repair or replace components as required.
2. Remove PCV valve from from grommet and remove hose. Shake PCV valve and confirm that plunger is free to move and rattle. Replace PCV valve if plunger is not free.
3. Start engine and run at idle. remove PCV valve from grommet, leaving connecting hose attached. Ensure vacuum is drawn through PCV valve. If vacuum is not felt, check connecting hose or intake fitting for blockage.

Vacuum Motor

Disconnect hot air tube at air cleaner. Disconnect vacuum hose from vacuum motor and connect vacuum test pump. Apply 7 in. Hg to vacuum motor and check if shutter valve opens to hot air tube connection. If shutter valve does not open and hold vacuum, replace air cleaner body.

Check Valve

Remove check valve from vacuum hoses. Check that air can be blown only in direction of arrow on check valve body. Replace check valve if not correct.

Air Cleaner Temperature Sensor

Disconnect vacuum hose from vacuum motor and connect vacuum test pump to hose. Apply 5 in. Hg to temperature sensor to check for sealing. Temperature sensor should be sealed below 86°F (30°C) and open above 86°F (30°C). Check hot idle compensator for leakage. See HOT IDLE COMPENSATOR in this article for test procedure. Replace or repair parts as required.

Decel Fuel Shutoff Valve

Turn ignition on and off. A clicking should be heard and felt at fuel shutoff valve. Start engine. With engine idling, disconnect connector to decel shutoff valve. Engine should stop. If engine does not die, check shutoff valve for sticking or binding.

Note. For more information on fuel shutoff system, see CODE 22 in TESTS W/CODES article in this section.

Anti-Afterburn Valve

1. With engine idling at normal operating temperature, check manifold vacuum signal line to valve for presence of vacuum. If vacuum is not present, check vacuum line for kinks, pinches and proper routing.
2. Remove vacuum line from valve for several seconds. Reconnect signal line. A change in RPM should be noted.
3. Place hand over bottom of anti-afterburn valve (fingers apart). Increase engine speed to about 2500 RPM. Quickly release throttle. After throttle is released, air should be drawn in through bottom of valve for 1-2 seconds.
4. If anti-afterburn valve does not respond as noted in steps 2 and 3, replace valve.

Scheme 47

See also:
• COOLANT TEMPERATURE SENSOR RESISTANCE