1991 FORD FESTIVA relay

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DEFOGGER - REAR WINDOW
1991 ACCESSORIES & SAFET Y EQUIPMENT Rear Window Defoggers - Rear Window
DESCRIPTION & OPERATION
The rear window defogger consists of an electrical grid on rear window glass. The rear window defogger switch is located in the instrument
cluster bezel. On Capri, the switch is a push type and includes a small indicator light in the switch to indicate when rear defogger is on. On
Festiva, the switch is a rocker type and includes a small indicator light in instrument cluster to indicate when rear defogger is on.
On Capri, the defogger circuit includes a 10-amp METER fuse which receives battery power from ignition switch and a 20-amp HTD B-
LIGHT fuse which has battery power at all times. The wire from the METER fuse goes to the rear defogger switch and then to the relay. The
wire from the HTD B-LIGHT fuse goes to the rear defogger relay and then to the grid. See Fig. 1
.

Fig. 1: Rear Window Defogger Wiring Diagram (Capri)

Courtesy of FORD MOTOR CO.
On Festiva, the defogger circuit includes a 15-amp DEFOG fuse which receives battery power from ignition switch. The wire from the fuse
goes to the rear defogger switch and then to the grid. The defogger circuit does not contain a relay. See Fig. 2
.
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Fig. 2: Rear Window Defogger Wiring Diagram (Festiva)
Courtesy of FORD MOTOR CO.
TROUBLE SHOOTING
DEFOGGER DOES NOT OPERATE
Blown fuse(s) or poor contact. Defogger switch defective. Defogger relay defective. Poor connections. Broken wire. Defective grid filament.
INDICATOR LIGHT DOES NOT WORK BUT DEFOGGER DOES WORK
Open circuit from rear defogger switch to instrument panel (Festiva). Defective light bulb. Defective flexible circuit on instrument cluster.
TESTING
SYSTEM TESTING
1. Ensure all in-line fuses or circuit breakers are okay. Turn ignition and control switches to ON position. Glass should feel warm after a
few min u t es.
2. If glass is not warm, use a test light or voltmeter to check for battery voltage at grid feed wire. If voltage is not correct, check wiring
harness, control switch and flexible circuit on instrument cluster. See FILAMENT TESTING.
REAR DEFOGGER SWITCH TESTING
Capri
Remove rear defogger switch. Using an ohmmeter, ensure continuity exists between terminals listed in table at specified switch positions. If
switch does not test as specified, replace rear defogger switch. See REAR DEFOGGER SWITCH CONTINUITY (CAPRI) table.
REAR DEFOGGER SWITCH CONTINUITY (CAPRI)
Festiva
Remove rear defogger switch. Using an ohmmeter, ensure continuity exists between terminals listed in table at specified switch positions. If
switch does not test as specified, replace rear defogger switch. See REAR DEFOGGER SWITCH CONTINUITY (FESTIVA) table. See Fig.
3 .
REAR DEFOGGER SWITCH CONTINUITY (FESTIVA)

Fig. 3: Identifying Rear Defogger Switch Terminals (Festiva)

Courtesy of FORD MOTOR CO.
REAR DEFOGGER RELAY TESTING
Unplug rear window defroster relay. Relay is located in left rear corner of luggage compartment. Apply battery voltage and ground to NOTE:On Capri, if indicator light is not working, replace switch.
TerminalPositionContinuity
BLK/YEL - BLK/WHTOffNo
BLK/YEL - BLK/WHTOnYes
TerminalPositionContinuity
BLK/WHT - BLK/BLUOffNo
BLK/WHT - BLK/BLUOnYes
RED/GRN - BLKOffNo
RED/GRN - BLKOnYes
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Black/White and Black wire terminals of relay. Check continuity of relay across 2 Black/Yellow wire terminals of relay. Continuity should
exist when relay is energized. When relay is de-energized, continuity should not exist.
FILAMENT TESTING
1. To locate breaks in grid wire filaments, attach a voltmeter to middle portion of each filament. Attach other meter probe to vertical
section of window grid.
2. If a grid is broken, meter will register either zero volt or battery voltage, depending on if grid is broken between or outside test leads. If
wire is not broken, meter will register about one half of battery voltage. To locate break, move probe along wire until meter needle
mo ves ab ru p t l y.
REMOVAL & INSTALLATION
REAR DEFOGGER SWITCH
Removal & Installation (Capri)
1. Disconnect negative battery cable. Pull out center storage compartment. Remove 2 nuts, 2 lower screws, and heater/radio bezel. Pull
outward and remove 2 trim covers, one located on each side of steering column.
2. Remove instrument panel bezel retaining screws and pull instrument bezel from dash. Disconnect electrical connector from rear
defogger switch. Depress tangs on both sides of switch and remove switch. To install, reverse removal procedure.
Removal & Installation (Festiva)
Disconnect negative battery cable. Remove steering column covers. Remove screws securing instrument panel bezel to instrument panel. Pull
instrument bezel away from instrument panel. Disconnect electrical connectors from switches in bezel. Compress rear defogger switch lock
tabs and remove switch from bezel. To install, reverse removal procedure.
WIRING DIAGRAMS
See appropriate chassis wiring diagram in the WIRING DIAGRAMS Section.
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00028302
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ELECT RICAL COMPONENT LOCAT OR
1991-92 ELECT RICAL COMPONENT LOCAT ION Ford Motor Co. Electrical Com ponents
BUZZERS, RELAYS & TIMERS
BUZZERS, RELAYS & TIMERS LOCATION
CIRCUIT PROTECTION DEVICES
CIRCUIT PROTECTION DEVICES LOCATION
CONTROL UNITS
CONTROL UNITS LOCATION
SENDING UNITS & SENSORS
SENDING UNITS & SENSORS LOCATION
MOTORS
MOTORS LOCATION
ComponentLocation
A/C Clutch Relay (1991)On right front of engine bay, near power
steering pump.
A/C RelayOn left front corner of engine bay, left of
cooling fan. See Fig. 1
& Fig. 2
A/C Wide Open Throttle (WAC) RelayOn left front corner of engine bay, left of
cooling fan. See Fig. 1
& Fig. 2 .
Cooling Fan RelayOn left front fender panel, near
headlight. See Fig. 1
& Fig. 2 .
Condenser Fan RelayOn left front of engine bay, left of
cooling fan. See Fig. 1
& Fig. 2 .
Daytime Running Light (DRL) Relay (Canada) (1992)On left front corner of engine bay, near
headlight. See Fig. 1
.
Fuel Pump RelayBehind left side of dash, near ECA.
Headlight RelayBehind left headlight. See Fig. 1 .
Horn RelayUnder left side of dash. See Fig. 3 .
Main RelayIn left front corner of engine bay, near
battery.
P a r kin g Ligh t R e l a yOn right front corner of engine bay. See
Fig. 1
.
Turn Signal/Flasher RelayUnder left side of dash, behind ECA.
See Fig. 3
.
ComponentLocation
A/C In-Line FuseOn left side of heater case.
Condenser Fan In-Line FuseOn right side of steering column.
Fuse PanelBehind access panel, to left of steering column.
Fusible LinksOn left front strut tower. See Fig. 1 .
ComponentLocation
Electronic Control Assembly (ECA)Behind left side of dash, left of steering column.
Passive Restraint ModuleUnder driver's seat.
ComponentLocation
Airflow MeterOn right front corner of engine bay. See Fig. 1 .
Coolant Temperature Sending UnitBelow thermostat housing.
Crankshaft Position SensorInside distributor. See Fig. 1 .
EGR Temperature Sensor (1991)In exhaust manifold, near EGR valve.
Engine Coolant Temperature (ECT) SensorOn top of engine, near injector No. 1.
Fuel Gauge Sending Unit (1992)In fu el t an k.
Throttle Position Sensor (TPS)On left side of throttle body. See Fig. 1 .
ComponentLocation
Blower MotorUnder center of dash, behind
radio.
Windshield Washer Motors:
Front (1991)On right front fender panel,
bottom of washer reservoir.
Front (1992)On left front corner of engine
bay, in front of battery.
RearOn body panel, behind right
rear quarter panel.
Windshield Wiper Motor
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Fig. 2: Ground Numbers & Locations (2001 & Prior Model Years)

WIRING DIAGRAM COMPONENT LOCATIONS
When trying to locate a component in a wiring diagram and you don't know the specific system where it is located, use this handy component
locator to find the system wiring diagram in which the component is located. Then, go to that system and locate the component within the
wiring diagram.
For example, if you don't know the specific system in which the ignition switch is located, look up ignition switch in the wiring diagram
component location tables and go to the appropriate wiring diagram(s) which contain either full or partial views of the ignition switch. The full
view of the ignition switch is located in Power Distribution.
The first listing for the component will be the full or most complete view of the component. Additional listings will be partial views of the
component. Not all components are used on all models.
All components will have a partial view in Ground Distribution and Power Distribution. Data Link Connectors show connecting circuits
between modules. Alternate names for components may be listed in wiring diagram component locations tables.
WIRING DIAGRAM COMPONENT LOCATIONS
ComponentWiring Diagram
ABS Electronic Control UnitAnti-Lock Brakes; Data Link Connectors
ABS Hydraulic UnitAnti-Lock Brakes
Acceleration SensorAnti-Lock Brakes
Accessory Delay RelayPower Windows
A/C Compressor Clutch RelayEngine Performance
A/C SensorEngine Performance
A/C Pressure SwitchEngine Performance
Adaptive Lamp Control ModuleExterior Lights
Air Bag(s)Air Bag Restraint System
Air Bag ModuleAir Bag Restraint System
Air Bag Sensor(s)Air Bag Restraint System
Air Injection Pump RelayEngine Performance
Air Temperature SensorOverhead Console
Alternator (Generator)Generators & Regulators
Anti-Theft Control ModuleAnti-Theft System; Starters
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Autolamp Control RelayHeadlight Systems; Daytime Running Lights
Automatic Shutdown (ASD) RelayEngine Performance; Generators & Regulators
Autostick SwitchEngine Performance
Auxiliary Battery RelayGenerators & Regulators
Back-Up LightsBack-Up Lights; Exterior Lights
Barometric (BARO) Pressure SensorEngine Performance
BatteryPower Distribution
Battery Temperature SensorEngine Performance
Body Control ModuleBody Control Computer; Anti-Theft System; Daytime Running
Lights; Engine Performance; Headlight Systems; Warning Systems
Boost Control SolenoidEngine Performance
Boost SensorEngine Performance
Brake Fluid Level SwitchAnalog Instrument Panels
Brake On/Off (BOO) SwitchCruise Control Systems; Engine Performance; Shift Interlock
Systems
Buzzer ModuleWarning Systems
Camshaft Position (CMP) SensorEngine Performance
Central Control ModuleAnti-Theft System
ClockspringAir Bag Restraint System; Cruise Control Systems; Steering
Column Switches
Clutch Pedal Position SwitchStarters
Clutch Start SwitchStarters
Combination MeterAnalog Instrument Panels
Constant Control Relay Module (CCRM)Engine Performance; Electric Cooling Fans
Convenience CenterPower Distribution; Illumination/Interior Lights
Convertible Top MotorPower Convertible Top
Convertible Top SwitchPower Convertible Top
Crankshaft Position (CKP) SensorEngine Performance
Cruise Control ModuleCruise Control Systems
Cruise Control SwitchCruise Control Systems
Condenser Fan Relay(s)Electric Cooling Fans
Data Link Connector (DLC)Engine Performance
Da yt ime R u n n in g Ligh t s M o d u l eDaytime Running Lights; Exterior Lights
Defogger RelayRear Window Defogger
Diagnostic Energy Reserve Module (DERM)Air Bag Restraint System
Discriminating Sensor (Air Bag)Air Bag Restraint System
DistributorEngine Performance
Door Lock ActuatorsPower Door Locks; Remote Keyless Entry
Door Lock Relay(s)Power Door Locks
Electrochromic MirrorPower Mirrors
Electronic Level Control (ELC) Height SensorElectronic Suspension
Electronic Level Control (ELC) ModuleElectronic Suspension
Engine Coolant Temperature (ECT) Sending UnitAnalog Instrument Panels
Engine Coolant Temperature (ECT) SensorEngine Performance
Engine Control ModuleEngine Performance; Generators & Regulators; Starters
ETACS ECUWarning Systems; Power Windows; Remote Keyless Entry
Evaporative (EVAP) Emissions CanisterEngine Performance
EVAP Canister Purge SolenoidEngine Performance
EVAP Canister Vent SolenoidEngine Performance
Exhaust Gas Recirculation (EGR) ValveEngine Performance
Fuel Tank Vacuum SensorEngine Performance
F o g Ligh t sHeadlight Systems; Daytime Running Lights
F o g Ligh t R e l a yHeadlight Systems; Daytime Running Lights
Fuel Door Release SolenoidPower Fuel Door Release
Fuel Gauge Sending UnitAnalog Instrument Panels
Fuel InjectorsEngine Performance
Fuel PumpEngine Performance
Fuel Pump RelayEngine Performance; Power Distribution
Fuse/Relay BlockPower Distribution
Fusible LinksPower Distribution; Generators & Regulators; Starters
GeneratorGenerators & Regulators; Engine Performance; Power Distribution
Generic Electronic Module (GEM)Body Control Modules; Electronic Suspension
Glow Plug RelayEngine Performance
Glow PlugsEngine Performance
GroundsGround Distribution
Headlight Door ModuleHeadlight Doors
Headlight RelayHeadlight Systems; Daytime Running Lights
HeadlightsHeadlight Systems; Daytime Running Lights
Heated Oxygen Sensor(s) (HO2S)Engine Performance
Heated Windshield Control ModuleHeated Windshields
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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
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Shift Lock ActuatorShift Interlock Systems
Side Marker LightsExterior Lights
SIR Coil Assembly (Clockspring)Air Bag Restraint System
Slip Ring (Clockspring)Air Bag Restraint System; Steering Column Switches
SRS Control ModuleAir Bag Restraint System
Starter MotorStarters
Starter Interrupt RelayStarters
Starter SolenoidStarters
Starter RelayStarters
Steering Wheel Position SensorAnti-Lock Brakes
StoplightsExterior Lights
Stoplight SwitchEngine Performance; Cruise Control Systems; Anti-Lock Brakes
Sun Roof ECUPower Sun Roof
Sun Roof MotorPower Sun Roof
Sun Roof Position SensorPower Sun Roof
TaillightsExterior Lights
Throttle Position (TP) SensorEngine Performance
Torque Converter Clutch Solenoid/SwitchEngine Performance
Traction Control SwitchAnti-Lock Brakes
Trailer Tow ConnectorExterior Lights
Trailer Tow RelayExterior Lights
Transmission/TransaxleEngine Performance
Transmission Control Module (TCM)Engine Performance; Starters
Transmission Range SensorStarters; Back-Up Lights; Engine Performance
Transmission Range SwitchBack-Up Lights; Engine Performance; Anti-Theft System
Turn Signal FlasherExterior Lights
Tu r n S ign a l Ligh t sExterior Lights
Twilight Sentinel SwitchHeadlight Systems; Daytime Running Lights
Vapor Canister Leak Detection PumpEngine Performance
Vehicle Control Module (VCM)Engine Performance
Vehicle Dynamic ModuleElectronic Suspension
Vehicle Speed Control ServoCruise Control Systems
Vehicle Speed SensorData Link Connectors; Analog Instrument Panels; Cruise Control
Systems; Electronic Suspension
Voltage RegulatorGenerators & Regulators
Water-In-Fuel SensorEngine Performance; Analog Instrument Panels
Wheel Speed SensorsAnti-Lock Brakes
Window Timer ModulePower Convertible Top
Windshield Intermittent Wiper RelayWiper/Washer Systems
Windshield Washer MotorWiper/Washer Systems
Wiper MotorWiper/Washer Systems
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00130983
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