
Height SensorElectronic Suspension
HornsSteering Column Switches
Horn RelaySteering Column Switches
Idle Air Control (IAC) Motor/ValveEngine Performance
Ignition Coil(s)Engine Performance
Ignition Key Lock CylinderAnti-Theft System
Ignition ModuleEngine Performance
Ignition SwitchPower Distribution; Engine Performance; Generators &
Regulators; Starters
Illuminated Entry ModuleIllumination/Interior Lights
Illumination LightsIllumination/Interior Lights
Impact SensorAir Bag Restraint System
Inertia Fuel Shutoff SwitchEngine Performance
In h ib it Rel ayStarters
Instrument ClusterAnalog Instrument Panels
Intake Air Temperature (IAT) SensorEngine Performance
Interior LightsIllumination/Interior Lights
In t erl o ck Swit chStarters
Junction BlockPower Distribution
Keyless Entry ReceiverRemote Keyless Entry
Key Reminder SwitchStarters
Knock SensorEngine Performance
Lamp Control ModuleExterior Lights
License Plate LampExterior Lights
Lighting Control ModuleLighting Control Modules; Anti-Theft System; Daytime Running
Lights; Headlight Systems
Lower RelayPower Convertible Top
Malfunction Indicator Light (MIL)Engine Performance; Instrument Panels
Manifold Absolute Pressure (MAP) SensorEngine Performance
Mass Airflow (MAF) SensorEngine Performance
Mega FuseGenerators & Regulators
Memory Seat/Mirror ModuleMemory Systems
M ir r o r De fo gge rRear Window Defogger
Moon Roof MotorPower Moon Roof
Moon Roof RelayPower Moon Roof
Multi-Function Control ModuleWarning Systems
Neutral Safety SwitchStarters
Oil Level SwitchEngine Performance
Oil Pressure Switch/Sending UnitAnalog Instrument Panels; Engine Performance
Overhead ConsoleOverhead Console
Oxygen Sensor(s) (O2S)Engine Performance
Parking Brake SwitchAnalog Instrument Panels
Park LightsExterior Lights
Park/Neutral Position SwitchStarters; Engine Performance; Anti-Theft System; Body Control
Module
Perimeter Lighting Control RelayExterior Lights
Power AmplifierPower Antennas
Power Antenna ModulePower Antennas
Power Antenna MotorPower Antennas
Power Distribution CenterPower Distribution; Generators & Regulators; Starters
Power Door Lock MotorsPower Door Locks
Power Mirror MotorsPower Mirrors; Memory Systems
Power Sliding Door ControllerPower Sliding Side Door
Power Seat MotorsPower Seats; Memory Systems
Power Steering Pressure SwitchEngine Performance
Power Top MotorPower Convertible Top
Power Top Relay(s)Power Convertible Top
Powertrain Control ModuleEngine Performance; Analog Instrument Panels; Cruise Control
Systems; Data Link Connectors; Generators & Regulators; Starters
Power Window MotorsPower Windows
Power Window Relay(s)Power Windows
Radiator Fan Motor(s)Electric Cooling Fans
Radiator Fan Relay(s)Engine Performance; Electric Cooling Fans;
Rainsense ModuleWiper/Washer Systems
Raise RelayPower Convertible Top
Remote Anti-Theft Personality (RAP) ModuleAnti-Theft System; Starters; Warning Systems
Seat Belt PretensionersAir Bag Restraint System
Seat Belt Retractor SolenoidPassive Restraints
Seat Belt SwitchAir Bag Restraint System; Passive Restraints
Shift Interlock SolenoidShift Interlock Systems
Page 5 of 6 MITCHELL 1 ARTICLE - GENERAL INFORMATION Using Mitchell1's Wiring Diagrams
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WIRING DIAGRAMS
1991 WIRING DIAGRAMS Ford Motor Co.
IDENTIFICATION
COMPONENT LOCATION MENU
COMPONENT LOCATIONS
WIRING DIAGRAMS
ComponentFigure No. (Location)
A/C RELAY3 (B 8)
A/T SELECT LIGHT3 (E 8)
ALTERNATOR1 (C 3)
BACK-UP LIGHT SWITCH5 (D 19)
BATTERY1 (A 2)
BLOWER SWITCH3 (C 9)
BRAKE WARNING SWITCH1 (C 2)
CIG LTR4 (E 14)
CLUTCH INTERLOCK SWITCH (M/T)1 (B 2)
CONDENSER FAN (A/T)3 (C 8)
COOLANT FAN MOTOR1 (D 3)
COOLANT FAN RELAY1 (D 3)
DEFOG SWITCH5 (C 16)
DIR/HAZARD SWITCH4 (B-C 12)
ELECT CONTROL ASSY (ECA)2 (A 4-7)
FRONT WASHER MOTOR1 (E 3)
FRONT WIPER MOTOR1 (E 3)
FRONT WIPER/WASHER SWITCH5 (A 16)
FUEL PUMP INERTIA SWITCH2 (D 4)
FUEL PUMP RELAY2 (C 4)
FUSE BLOCK3 (D-E 9-10)
HEADLIGHT RELAY4 (D 14)
HORN RELAY3 (E 11)
HORN SWITCH4 (E 15)
IGNITION COIL2 (E 5)
IGNITION KEY REMINDER SWITCH4 (E 13)
IGNITION SWITCH3 (C-D 11)
INSTRUMENT CLUSTER4 (A-E 15)
INSTRUMENT PANEL LIGHT CONTROL4 (D-E 12)
INTERIOR LIGHT SWITCH4 (E 14)
LIGHT SWITCH4 (C-D 12)
MAIN FUSE PANEL1 (A 3)
MAIN RELAY2 (D 5)
NEUTRAL SAFETY SWITCH (A/T)1 (B 2)
PARKING LIGHT RELAY4 (C 14)
PASSIVE RESTRAINT CONTROL MODULE3 (A 11)
REAR WASHER MOTOR5 (D 17)
REAR WIPER/WASHER SWITCH5 (E 16)
SHIFT LOCK SERVO ASSY4 (A 12)
STARTER1 (B 3)
STOP LIGHT SWITCH5 (D 19)
TIMER/BUZZER UNIT4 (E 12)
TRUNK LIGHT5 (B 16)
WAC RELAY3 (B 8)
Page 1 of 6 MITCHELL 1 ARTICLE - WIRING DIAGRAMS 1991 WIRING DIAGRAMS Ford Motor Co.
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Fig. 3: A/C & Heat, Fuse Block, Passive Restraint,Ign (Grid 8
-11)
Page 4 of 6 MITCHELL 1 ARTICLE - WIRING DIAGRAMS 1991 WIRING DIAGRAMS Ford Motor Co.
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ENGINE COOLING FAN
1990-92 ENGINE COOLING Ford Motor Co. Engine Cooling Fans
DESCRIPTION
Power for cooling fan is provided by the 20-amp COOLING fuse (Capri) or C-FAN fuse (Festiva). Cooling fan is activated when ground is
supplied for fan motor. On Festiva, ground can be supplied by fuel system ECA (located under the left side of dash), A/C cooling fan relay (if
equipped) or cooling fan relay. See Fig. 1
. On all models, when cooling fan is energized, relay contacts are open; when cooling fan is NOT
energized, relay contacts are closed, providing ground through closed contacts to activate cooling fan. See Fig. 2
.
Cooling fan relay is energized when coolant temperature switch is closed. This occurs when coolant temperature is less than 212°F (1 00 °C)
for Capri or 207°F (97°C) for Festiva. At temperatures greater than 212°F (100°C) for Capri or 207°F (97°C) for Festiva, coolant temperature
switch opens and cooling fan relay is de-energized, closing relay contacts and energizing cooling fan.
When ECA senses A/C request, it energizes A/C cooling fan relay by providing a ground for relay windings on ECA pin 1Q. Power for the
A/C cooling fan relay is provided by the HEATER fuse. On Capri, when A/C cooling fan relay is energized, it opens the power circuit for the
cooling fan relay. On Festiva, when A/C cooling fan relay is energized, it provides an alternate path to ground for cooling fan mo t o r. E CA al so
provides an alternate path to ground (at ECA pin 1R) for cooling fan motor based on input from coolant temperature sensor to ECA pin 2Q.
Fig. 1: Locating Cooling Fan & A/C Relays
Courtesy of FORD MOTOR CO.
TROUBLE SHOOTING
COOLING FAN DOES NOT OPERATE OR OPERATES ERRATICALLY
If cooling fan does not run at any time, or operates erratically, check the following items to help locate fault.
Check power fuse.
Check cooling fan relay.
Check coolant temperature switch.
Check cooling fan wiring harness.
Check cooling fan motor.
Check A/C cooling fan relay.
COOLING FAN RUNS CONTINUOUSLY
If cooling fan runs continuously, check the following items to help locate fault.
Check cooling fan relay.
Check coolant temperature switch.
Check cooling fan wiring harness.
Check cooling fan motor.
Check A/C cooling fan relay.
Page 1 of 3 MITCHELL 1 ARTICLE - ENGINE COOLING FAN 1990-92 ENGINE COOLING Ford Motor Co. Engine Cooling Fans
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COOLING FAN DOES NOT RUN WITH A/C ON
If cooling fan does not run with A/C on, check the following items to help isolate fault.
Check A/C cooling fan relay.
Check cooling fan wiring harness.
TESTING
VOLTAGE SUPPLY TEST
Disconnect cooling fan motor connector. Turn ignition on. Check for voltage at Yellow wire terminal of connector. If voltage is NOT present,
check for blown 20-amp COOLING fuse (Capri) or C-FAN fuse (Festiva) or open in Yellow wire between cooling fan and fuse.
Disconnect cooling fan relay connector. Cooling fan relay is located in the left front corner of engine compartment. Turn ignition on. Check
for voltage at Yellow (Capri) or Black/Yellow (Festiva) wire terminal of connector. If voltage is NOT present, check for blown 30-amp
HEATER fuse on Capri or 10-amp METER fuse on Festiva or open in Black/Yellow wire between cooling fan relay and fuse.
Disconnect A/C cooling fan relay connector. On Capri, A/C relay is located in the left rear corner of the engine compartment, on firewall. On
Festiva, A/C relay is located in the left front corner of engine compartment, under a triple relay cover. Relay may be identified by wire colors
to relay connector. See Fig. 2
and Fig. 3 . Turn ignition on. Check for voltage at Blue wire terminal of connector. If voltage is NOT present,
check for blown 15-amp HEATER fuse or open in Blue wire between A/C cooling fan relay and fuse.
GROUND CIRCUIT TEST
Turn ignition off. Unplug connectors from cooling fan and A/C cooling fan relays. Check for continuity between ground and Black wire
terminal of relay connectors. If continuity is NOT present, repair Black ground wire.
FAN MOTOR TEST
Disconnect fan motor wire connector. Apply ground and battery voltage to motor connector. Fan should run. If fan does not run, replace
cooling fan motor.
COOLING FAN RELAY TEST
Unplug cooling fan relay connector. Apply battery voltage and ground to Yellow and Green/Red (Capri) or Black/Yellow and Green/Yellow
(Festiva) wire terminals of relay. Check continuity of relay across Yellow/Green (Capri) or Yellow/Red and Black (Festiva) wire connector
terminals. Ensure continuity is NOT present while relay is energized. When relay is de-energized, continuity should exist.
A/C COOLING FAN RELAY TEST
Unplug A/C relay connector. Apply battery voltage and ground to Blue and White (Capri) or Blue and Green (Festiva) wire terminals of relay.
Check continuity of relay across Blue and Red (Capri) or Yellow/Red and Black (Festiva) wire connector terminals. On Capri, ensure
continuity does NOT exist while relay is energized. On Festiva, ensure continuity exists while relay is energized. On Capri, when relay is de-
energized continuity should exist. On Festiva, when relay is de-energized, continuity should NOT exist.
COOLANT TEMPERATURE SWITCH TEST
Disconnect connector from coolant temperature switch located in thermostat housing. With coolant temperature less than 200°F (93°C) for
Capri or 194°F (90°C) for Festiva, check continuity between ground and coolant temperature switch. Ensure continuity exists. Start engine
and allow coolant temperature to reach 200°F (93°C) for Capri or 207°F (97°C) for Festiva. Check continuity between ground and coolant
temperature switch terminal. Continuity should NOT be present. If switch does not test as indicated, replace switch.
HARNESS & CIRCUIT CHECK TEST
Turn ignition off. Disconnect harness connectors of the following components: ECA, cooling fan motor, coolant temperature switch, cooling
fan relay and A/C cooling fan relay. Using an ohmmeter, check for continuity on the related harness leads of each connector. See Fig. 2
and
Fig. 3
.
WIRING DIAGRAMS
For further detail, see appropriate chassis wiring diagram in the WIRING DIAGRAMS article in the WIRING DIAGRAMS section.
Page 2 of 3 MITCHELL 1 ARTICLE - ENGINE COOLING FAN 1990-92 ENGINE COOLING Ford Motor Co. Engine Cooling Fans
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Fuel Pump Circuit
1. Turn ignition on. Connect jumper wire between fuel pump test connector terminals. See Fig. 1 or Fig. 2 . Turn ignition on to activate
fuel pump.
2. Listen for fuel pump sound. If there is no sound, check main fuse, inertia switch (located at left rear shock tower), fuel pump rel ay, fu el
pump and all electrical connections.
Fig. 1: Festiva Fuel System Electrical Schematic
Courtesy of FORD MOTOR CO.
(1)For 1991 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. For 1992 fuel pressure specifications,
see FUEL PRESSURE SPECIFICATIONS
article.
Page 2 of 4 MITCHELL 1 ARTICLE - F - BASIC TESTING 1991-92 ENGINE PERFORMANCE Ford Motor Co. Basic Diagnostic Proced
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STG CIRCUIT PIN IDENTIFICATION
1. Turn ignition off. Install BOB, leaving ECA disconnected. Measure resistance between switch BOB test pin and ground. Cycle switch. I
f
resistance is greater than 10,000 ohms with switch open and less than 5 ohms when switch is closed, switch is okay; go to step 4). If
resistance is not greater than 10,000 ohms with switch open, or greater than 5 ohms when switch is closed, go to next step.
2. Turn ignition off. Disconnect switch. Connect ohmmeter between switch terminals on 2-pin switches, or between ground and switch
ECA terminal on multi-pin or one-pin switches. Cycle switch. If resistance is not greater than 10,000 ohms with switch open, or is
greater than 5 ohms when switch is closed, replace switch. If resistance is greater than 10,000 ohms with switch open and less than 5
ohms when switch is closed, switch is okay; go to next step.
3. Turn ignition off. Install BOB, leaving ECA disconnected. Measure resistance between BOB pin for suspected switch and BOB pins 26,
37, 57, and 60. If any measurement is less than 10,000, repair shorted wire in question. If all measurements are greater than 10,000
ohms, go to next step.
4. Turn ignition off. Install BOB, leaving ECA disconnected. Measure resistance between BOB pin for suspected switch and switch
connector. If resistance is greater than 5 ohms, repair wire in question. If sent here from SWITCH MONITOR TEST in QUICK TESTS,
replace ECA; otherwise, return to QUICK TESTS.
PINPOINT TEST STP - SWITCH TO POWER
STP CIRCUIT PIN IDENTIFICATION
1. Turn ignition off. Install BOB, leaving ECA disconnected. Turn ignition on. Cycle switch in question. Measure voltage between switch
BOB test pin and ground. If voltage changes from less than 4 volts to more than 10 volts, switch is okay. If sent here from SWITCH
MONITOR TEST in QUICK TESTS, replace ECA. If sent here from elsewhere in QUICK TESTS, return to QUICK TESTS. If voltage is
not as specified, go to next step.
2. Turn ignition on. Measure voltage at switch in question on wire to ECA. Cycle switch. If voltage changes from less than 4 volts to more
than 10 volts, repair wire from switch to ECA. If voltage does not change from less than 4 volts to more than 10 volts, go to next step.
3. Turn ignition on. Install BOB, leaving ECA disconnected. Measure resistance between BOB test pin for switch in question and ground
and between BOB test pin and BOB pins 37, 57, and 26. If resistance is greater than 10,000 ohms for all measurements, go to next step.
If resistance is not greater than 10,000 ohms for all measurements, repair wire to switch.
4. Disconnect switch. Measure resistance between switch terminals. Cycle switch. If resistance is less than 5 ohms with switch closed and
greater than 10,000 ohms with switch open, switch is okay. If sent here from SWITCH MONITOR TEST in QUICK TESTS, return to
QUICK TESTS. If sent here from elsewhere in QUICK TESTS, replace ECA. If resistance is not as specified, replace switch.
PINPOINT TEST VPWR - VEHICLE POWER
SwitchECA PinBOB PinWire Color
1.3L
ACS1Q10BLU/RED
BLMT1S23GRN
IDL1N18YEL/BLK
NGS/CES (1) 1V43BLU/WHT
PSPS1P19PNK
WOT2L27YEL
1.6L
BPS (2) 2L12LT GRN/BLK
IDL1E18GRN/ORG
NGS/CES (1) 1G8RED/BLU
PSPS1K19GRN/RED
(1)Manual transmission only.
(2)Turbo only.
NOTE:For 1.3L, blower m otor resistor m ust be disconnected, HEAT ER fuse m ust be rem oved, and blower
m otor switch m ust be in position "1" when testing ACS signal.
NOTE:Enter this test only when directed here from QUICK T EST S.
SwitchECA PinBOB PinWire Color
1.3L
ACS1Q10GRN
BOO1O2GRN/RED
DEF1T30BLK/BLU
Fan1R22YEL/RED
HLDT1U28WHT
VST1C5BLK/RED
1.6L
BOO1J3WHT/GRN
VST3B5BLK/RED
NOTE:Enter this test only when directed here from another PINPOINT T EST . T o prevent replacem ent of good
com ponents, note following non-EEC com ponents m ay be faulty: ignition switch, alternator, battery
cables, ground straps, or voltage regulator. T his test is intended to diagnose only ECA, wiring harness
circuits, and battery voltage.
Page 17 of 20 MITCHELL 1 ARTICLE - G - TESTS W/CODES 1991-92 ENGINE PERFORMANCE Ford Motor Co. Self-Diagnostics
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EBL
Electronic Back Light
ECM
Engine Control Module
ECT
Engine Coolant Temperature Sensor
EDIS
Electronic Distributorless Ignition System
EEC
Electronic Engine Control
EECS
Evaporative Emission Control System
EEPROM
Electronically Erasable PROM
EFE
Early Fuel Evaporation
EGO
Exhaust Gas Oxygen Sensor
EGR
Exhaust Gas Recirculation
ESA
Electronic Spark Advance
ESC
Electronic Spark Control
EST
Electronic Spark Timing
EVAP
Fuel Evaporative System
EVIC
Electronic Vehicle Information Center
EVP
EGR Valve Position Sensor
Exc.
Except
"F"
° F
Fahrenheit (Degrees)
F/B
Fuse Block
Fed.
Page 6 of 15 MITCHELL 1 ARTICLE - GENERAL INFORMATION Commonly Used Abbreviations
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