1991 FORD FESTIVA wiring

Fig. 2: Identifying Alternator Test Terminals

Courtesy of FORD MOTOR CO.
1. Turn ignition switch to OFF position. Connect positive voltmeter lead wire to alternator "B" terminal and negative wire to ground. See
Fig. 2
. Ensure voltmeter indicates battery voltage. If voltmeter indicates zero volts, an open circuit exists in wire between "B" terminal
and battery positive terminal.
2. Remove voltmeter. Disconnect negative battery cable. Remove output lead from alternator terminal "B". Connect a 100-amp ammeter in
series between "B" terminal and disconnected output lead. Connect positive lead of ammeter to "B" terminal and negative lead to
disconnected output wire.
3. Connect voltmeter in parallel between alternator "B" terminal and battery positive terminal. Connect positive lead wire of voltmeter to
"B" terminal and negative lead wire to positive terminal of battery. Reconnect negative battery cable.
4. Install tachometer (if necessary) to monitor engine RPM. Start engine. Turn all lights and accessories on and depress brake pedal to load
system. Increase engine speed to 2500-3000 RPM. Ensure alternator output is at least 35 amps.
5. Observe voltmeter reading. If voltmeter indicates .2 volt and amperage output is at least 35 amps, system is okay. If voltage drop is
greater than .2 volt, wiring is defective between alternator "B" terminal and battery positive terminal.
6. Allow engine to idle. Turn off all accessories to remove load from system. Disconnect voltmeter. Connect negative lead of voltmeter to
ground. Using positive lead of voltmeter, backprobe "S" terminal connector at rear of alternator. See Fig. 2
.
7. Increase engine speed to 2500-3000 RPM. With no load on system, ammeter should read 5 amps or more. Battery voltage with no load
at indicated speed should be 14.1-14.7 volts. If amperage output is less than indicated with or without load and no external faults exist
in alternator circuit, overhaul or replace alternator.
BENCH TESTING
Rotor
Check continuity across rotor slip rings. If no continuity exists, replace rotor. Check continuity between individual slip rings and rotor
core/shaft. If continuity exists, rotor coil or slip ring is grounded. Replace rotor.
Stator
Ensure no continuity exists between stator coil leads and stator core. Check continuity between leads of stator coil. If continuity does not
exist, replace stator.
Brushes
Inspect brushes. Replace brushes if worn to wear line (leading edge of small square cast into brush). Use a spring pressure gauge to push each
NEW brush into its holder until .079" (2 mm) projects from holder. Spring force should be 10.6-15.6 oz. (.3-.4 kg). If spring force is not
within specification, replace brush spring.
Rectifier
1. Using an ohmmeter, check for continuity between positive side of diode leads and heat sink. If no continuity exists from any positive
diode lead to heat sink, replace rectifier assembly.
2. Reverse ohmmeter leads, and check for continuity between negative side of diodes and heat sink. If continuity exists from any n e ga t ive
diode lead to heat sink, replace rectifier assembly.
3. Check diode trio (smaller diodes between main diode leads) for continuity in both directions. Continuity should exist in one direction
only. If any diode shows continuity in both directions or does not show continuity in either direction, replace diode trio.
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3. If voltage is not present or is less than 8 volts at starter solenoid terminal "S", malfunction in circuit to terminal "S" is indicated. Proceed
to the following tests.
IGNITION SWITCH TEST
1. Locate ignition switch connector under dash. Using a 12-volt test light or voltmeter, ensure voltage is present on Black/Yellow wire
when ignition switch is turned to RUN or ON position. This will verify proper operation of ignition switch.
2. If there is no voltage on Black/Yellow wire, the problem is either ignition switch or circuit between battery and ignition switch.
CLUTCH ENGAGE SWITCH (M/T) TEST
Unplug clutch engage switch from main wiring harness. Using an ohmmeter, check for continuity across switch terminals. Continuity should
exist when switch plunger is pushed in and should not exist when switch plunger is released. If clutch engage switch does not operate as
specified, replace switch.
NEUTRAL SAFETY SWITCH (A/T) TEST
Unplug neutral safety switch from main wiring harness. Using an ohmmeter, check for continuity across switch terminals "A" and "B". See Fig.
2 . Place transmission shift selector in Park or Neutral position. Continuity should exist between terminals "A" and "B". Continuity should not
exist in any other transmission shift selector positions. If switch does nor operate as specified, replace switch.

Fig. 2: Identifying Neutral Safety Switch Terminals

Courtesy of FORD MOTOR CO.
VOLTAGE DROP TEST
1. Disconnect and ground coil wire from distributor cap to prevent engine from starting. Connect remote starter switch between starter
solenoid terminal "S" and battery positive terminal. See Fig. 3
.
2. Using a digital voltmeter set on low scale, connect positive voltmeter lead to battery positive terminal. Connect negative lead to starter
solenoid terminal "M". See Fig. 3
.
3. Engage remote starter switch. Observe and record voltmeter reading. Voltmeter reading should be less than .5 volt. If voltage at terminal
"M" is greater than .5 volt, move negative voltmeter lead to solenoid terminal "B", and repeat test.
4. If voltage at terminal "B" is less than .5 volt, inspect solenoid cable connections and solenoid contacts for problem.
5 . Cl ean so l en o id t ermin al s "B", "M" an d "S", an d rep eat st ep s 1 ) through 4). If voltmeter still reads greater than .5 volt at termin al "M"
and less than .5 volt at terminal "B", solenoid contacts are bad.
6. If voltmeter reads greater than .5 volt at terminal "B", clean cables and connections at solenoid. If voltmeter still reads greater than .5
volt, check for poor positive battery cable connection or bad cable. Repair or replace as necessary.
7. To locate excessive voltage drop, move negative voltmeter lead toward battery, and check each connection point. When high voltmeter
reading is no longer present, last connection point is bad.
NOTE:Make all voltm eter connections at com ponent term inal rather than at cable or wire end.
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SOLENOID TEST
Disconnect wiring and cables from solenoid. Using an ohmmeter, check for continuity between terminal "M" and body of starter solenoid. See
Fig. 1
. Continuity should exist. If continuity does not exist, replace solenoid.
ARMATURE TEST
1. Place armature in growler. Turn on growler and hold a piece of hacksaw blade over armature. Slowly rotate armature. If hacksaw blade
is attracted to core or if it vibrates, replace armature.
2. Remove armature from growler. Using an ohmmeter, check continuity between commutator and core. If continuity exists, replace
armature. Check continuity between commutator and shaft. If continuity exists, replace armature.
3. Check continuity between each commutator segment. If an open exists between any 2 segments, replace armature.
COMMUTATOR TEST
1. Clean surface of commutator and polish with No. 400 grit sandpaper (if required). If surface is scored, out of round or pitted, turn
commutator on a lathe.
2. Maximum commutator runout and minimum diameter of commutator must not exceed specification after turning. See STARTER
MOTOR SPECIFICATIONS table.
3. Commutator mica undercut depth should be .02-.03" (.5-.8 mm). If undercut depth is not within specification, undercut with a hacksaw
blade to standard depth.
BRUSH & SPRING TEST
1. Connect ohmmeter between positive brush holder and negative brush holder. If ohmmeter indicates continuity, brush holder assemb l y is
shorted and must be replaced.
2. Check brush length. See STARTER MOTOR SPECIFICATIONS
table. If brush length is less than specification, replace brushes.
3. Check spring tension. Spring tension should be 2.0-4.3 Lbs. (8.8-19.1 N.m). Ensure brushes move freely in holders.
FIELD COIL TEST
1. Connect ohmmeter between field lead and soldered portion of brush lead. If continuity does not exist, repair or replace field coil.
2. Check field coil for shorts to ground by connecting ohmmeter between field lead and starter housing. If continuity exists, repair or
replace field coil.
OVERHAUL

Fig. 6: Exploded View of Starter Motor Assembly

Courtesy of FORD MOTOR CO.
STARTER MOTOR SPECIFICATIONS
STARTER MOTOR SPECIFICATIONS NOTE:For exploded view of starter assem bly, see Fig. 6
.
ApplicationSpecification
Brush Length
Minimum.45" (11.5 mm)
New.67" (17 mm)
Brush Spring Force2.0-4.3 Lbs. (8.8-19.1
N.m)
Commutator
Runout.002" (.05 mm)
Min imu m Diamet er1.22" (31.0 mm)
Segment Depth.02-.03" (.5-.8 mm)
Pinion Gap.020-.080" (0.5-2.0
Page 5 of 6 MITCHELL 1 ARTICLE - STARTER 1991 ELECTRICAL Starters
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Back To Article
1991 System Wiring Diagram s
Ford - Festiva
COOLING FAN

Fig. 1: Cooling Fan Circuit

DEFOGGERS

Fig. 2: Defogger Circuit

HORN
Page 1 of 5 MITCHELL 1 ARTICLE - 1991 System Wiring Diagrams Ford - Festiva
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Fig. 3: Horn Circuit

POWER MIRRORS

Fig. 4: Power Mirror Circuit

RADIO
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Fig. 5: Radio Circuits

STARTING/CHARGING

Fig. 6: Charging Circuit

Page 3 of 5 MITCHELL 1 ARTICLE - 1991 System Wiring Diagrams Ford - Festiva
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Fig. 7: Starting Circuit

WIPER/WASHER

Fig. 8: Front Wiper/Washer Circuit

Page 4 of 5 MITCHELL 1 ARTICLE - 1991 System Wiring Diagrams Ford - Festiva
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Fig. 9: Rear Wiper/Washer Circuit

Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00121193
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