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ST EERING COLUMN SWIT CHES
1991 ACCESSORIES & SAFET Y EQUIPMENT Ford Motor Co. Steering Colum n Switches
DESCRIPTION & OPERATION
DISABLING AIR BAG SYSTEM
To disable SRS, disconnect battery cable. Unplug back-up power supply 3-way harness connector. System is now disabled. Back-up power
supply is mounted to inside of instrument panel, left of glove box opening. Glove box door must be opened past its stops and lowered toward
floor to access back-up power supply.
ACTIVATING AIR BAG SYSTEM
To activate SRS, reconnect back-up power supply connector and negative battery cable. From passenger's side of vehicle, turn ignition switch
to RUN position. System is now activated. Check AIR BAG light to ensure system is functioning properly.
TESTING
HAZARD WARNING SWITCH & TURN SIGNAL SWITCH
Capri
1. Remove steering column covers to access turn signal/hazard switch connectors. Turn ignition on. Using a 12-volt test light, ensure
battery voltage is present at Green/Red and Green/Yellow wires at turn signal/hazard switch connectors. If battery voltage is not present,
check METER and HAZARD fuses. Also check hazard and turn signal flasher units and replace as necessary.
2. If battery voltage is present at Green/Red and Green/Yellow wires, place turn signal switch in RIGHT position. Check both Green/White
wires at switch connector. Test light should flash on and off in constant cycles.
3. Place turn signal switch in LEFT position. Check both Green/Black wires at switch connector. Test light should flash on and off in
constant cycles. If turn signal/hazard switch does not function as specified, replace switch.
Festiva
1. Remove steering column covers to access turn signal/hazard switch connectors. Turn ignition on. Using a 12-volt test light, ensure
battery voltage is present at White/Black and Black/Yellow wires at hazard and turn signal switch connectors. If battery voltage is not
present, check METER and HAZARD fuses.
2. If battery voltage is present at White/Black and Black/Yellow wires, place turn signal/hazard switch in RIGHT position. Check
Green/Black wire at switch connector. Test light should flash on and off in constant cycles.
3. Place turn signal/hazard switch in LEFT position. Check Green/White wire at switch connector. Test light should flash on and off in
constant cycles. If turn signal/hazard switch does not function as specified, replace switch.
HEADLIGHT SWITCH
Capri
1. Remove instrument panel bezel to access switch connector. See HEADLIGHT SWITCH under REMOVAL & INSTALLATION.
Disconnect switch electrical connector. Measure voltage between Red and Red/White wires of headlight switch vehicle harness and
ground. If battery voltage is present, go to next step. If battery voltage is not present, check HEAD and MAIN fuses and Red and
Red/White wires between switch and fuse block.
2. Press headlight switch to first position. Using a self powered test light or ohmmeter, check continuity between switch terminals which
correspond to Red and Red/Green wires of vehicle harness connector. Continuity should not exist. If continuity exists, replace switch.
3. Press headlight switch to second position. Check continuity between switch terminals which correspond with the Red and Red/Green
wires of vehicle harness connector. Continuity should exist. If switch does not function as described, replace headlight switch. If swit ch
functions as described but headlights do not work, go to next step.
4. Remove steering column covers to access Flash-To-Pass switch connector. Using a 12-volt test light or voltmeter, place switch in
position indicated in table and check voltage between indicated wire terminals and ground. See FLASH-TO-PASS SWITCH TEST
(CAPRI) table. If switch does not function as indicated, replace switch.
FLASH-TO-PASS SWITCH TEST (CAPRI) CAUTION: On Capri m odels with Supplem ental Restraint System (SRS), observe safety precautions. T he air bag
system is powered directly from the battery and back-up power supply. Before any repairs are
perform ed, disconnect and shield battery ground cable. Disconnect the back-up power supply and wait
at least 15 m inutes BEFORE servicing ANY air bag com ponent. Use caution when working near steering
colum n. Air bag could accidentally deploy at any tim e.
NOTE:T he following disabling sequence is ONLY for com ponent replacem ent purposes.
Switch PositionWire ColorVoltage
Off
Headlights OffREDBattery
"All other wires0
Headlights OnRED, RED/GRN,
RED/BLKBattery
"All other wires0
On
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Festiva
Disconnect headlight switch. Using an ohmmeter, place switch in position indicated in table and check continuity between switch terminals
that correspond to wire colors listed. See HEADLIGHT SWITCH CONTINUITY TEST (FESTIVA) table. If switch does not function
indicated, replace switch.
HEADLIGHT SWITCH CONTINUITY TEST (FESTIVA)
IGNITION SWITCH
Capri
Remove lower steering column cover to gain access to ignition switch electrical connector. Connect a self-powered test light or ohmmeter
between blade terminals indicated in table. See IGNITION SWITCH CONTINUITY (CAPRI) table. Continuity should not exist between any
blade terminal and chassis ground in any switch position except proof circuit (162/997) in START position. See Fig. 1
.
IGNITION SWITCH CONTINUITY (CAPRI)
Fig. 1: Identifying Ignition Switch Terminals (Capri)
Courtesy of FORD MOTOR CO.
Festiva
Remove lower steering column cover to gain access to ignition switch electrical connector. Using a self-powered test light or ohmmeter, ensure
continuity exists between terminals listed in table at specified switch positions. If switch does not test as specified, replace ignition switch. See
IGNITION SWITCH CONTINUITY (FESTIVA) table. See Fig. 2
.
IGNITION SWITCH CONTINUITY (FESTIVA)
Headlights OffRED, RED/WHTBattery
"All other wires0
Headlights OnRED, RED/GRN,
RED/WHTBattery
"All other wires0
Switch PositionWire ColorContinuity
FlashRED/BLK to BLKYes
LowWHT to RED/BLKYes
HighWHT to RED/WHTYes
1RED/YEL to BLKYes
2RED/BLK to BLKYes
OffBLK to AllNo
Switch PositionContinuity Should Exist Only Between
ACC37, 297
LOCKNo Continuity
OFFNo Continuity
RUN37, 16, 687, 297
START977, 162 (Chassis Ground), 37, 32, 262
NOTE: Circuit pairs 37, 687 and 297 are connected together inside ignition switch.
TerminalPositionContinuity
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Fig. 2: Underhood Fusible Link Block Identification
Courtesy of FORD MOTOR CO.
Fusible Link Identification
A - Brown (PTC) (1988-89 Carburetor) EFE Carburetor Heater
A - Brown (EGI) (1989-93 EFI) EFI System (1989-92), EGI-EFI System (1993)
B - Red (Main) Back-Up, Interior & Parking Lights, Brakelights, Taillights, Horn, Luggage Compartment Light, Turn Signal & Hazard
F l a sh e r Ligh t s, C l u st e r & Wa r n in g Ligh t s, R a d io , C iga r e t t e Ligh t e r , C h a r gin g & E missio n C o n t r o l S yst e ms, Wip e r / Wa sh e r S yst e ms,
A/C-Heater System, Cooling Fan System, Rear Window Defroster, Ignition & Starting Systems, Shift Lock System, Remote Control
Mirror, Ignition Key Reminder, Passive Restraint System (1990-93)
C - Brown (Head) Headlights, Daytime Running Lights, Starting & Charging System
BATTERY SPECIFICATIONS
All 1988-92 models use a BX-35 battery. The 1993 Festiva uses a 50D 20L standard battery.
CAUTIONS & WARNINGS
BATTERY WARNING
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off all lights and accessories to avoid damaging the electrical system. Be sure to use
fuse with the correct indicated amperage rating. The use of an incorrect amperage rating fuse may result in a dangerous electrical system
overload.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning that brake pads need replacement.
CAUT ION: When battery is disconnected, vehicles equipped with com puters m ay lose m em ory data. When battery
power is restored, driveability problem s m ay exist on som e vehicles. T hese vehicles m ay require a
relearn procedure. See COMPUTER RELEARN PROCEDURES
article in the GENERAL INFORMAT ION
section.
WARNING:When battery is disconnected, vehicles equipped with com puters m ay lose m em ory data. When battery
power is restored, driveability problem s m ay exist on som e vehicles. T hese vehicles m ay require a
relearn procedure. See COMPUTER RELEARN PROCEDURES
article in GENERAL INFORMAT ION
section.
Page 2 of 3 MITCHELL 1 ARTICLE - FUSES & CIRCUIT BREAKERS Fuses & Circuit Breakers 1988-93 Festiva
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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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Fig. 1: Engine Compartment & Headlights (Grid 1
-3)
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Fig. 2: Ignition Primary Trouble Shooting Chart
STARTER TROUBLE SHOOTING
BASIC STARTER TROUBLE SHOOTING CHART
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Starter Fails to Operate
Dead battery or bad connections between starter and batteryCheck battery charge and all
wires and connections to
starter
Ignition switch faulty or misadjustedAdjust or replace ignition
switch
Open circuit between starter switch ignition terminal on starter relayCheck and repair wires and
connections as necessary
Starter relay or starter defectiveSee Testing in STARTER
article
Open solenoid pull-in wireTesting in STARTER article
Starter Does Not Operate and Headlights Dim
Weak battery or dead cellCharge or replace battery as
necessary
Loose or corroded battery connectionsCheck that battery connections
are clean and tight
Internal ground in starter windingsSee Testing in STARTER
article
Grounded starter fieldsSee Testing in STARTERS
Armature rubbing on poleSee STARTER article shoes
Starter Turns but Engine Does Not Rotate
Starter clutch slippingSee STARTER article
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Fig. 4: Ignition Primary Trouble Shooting Chart
STARTER TROUBLE SHOOTING
BASIC STARTER TROUBLE SHOOTING CHART
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Starter Fails to Operate
Dead battery or bad connections between starter and batteryCheck battery charge and all
wires and connections to
starter
Ignition switch faulty or misadjustedAdjust or replace ignition
switch
Open circuit between starter switch ignition terminal on starter relayCheck and repair wires and
connections as necessary
Starter relay or starter defectiveSee Testing in STARTER
article
Open solenoid pull-in wireSee Testing in STARTER
article
Starter Does Not Operate and Headlights Dim
Weak battery or dead cellCharge or replace battery as
necessary
Loose or corroded battery connectionsCheck that battery
connections are clean and
tight
Internal ground in starter windingsSee Testing in STARTER
article
Grounded starter fieldsSee Testing in STARTERS
Armature rubbing on pole shoesSee STARTER article
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Circuits with external injector resistors. Used predominately on some Asian & European systems, they are used to reduce the available
voltage to an injector in order to limit the current flow. This lower voltage can cause a dim flash on a noid light designed for full voltage.
Circuits with current controlled injector drivers (e.g. "Peak and Hold"). Basically, this type of driver allows a quick burst of
voltage/current to flow and then throttles it back significantly for the remainder of the pulse width duration. If a noid light was designed
for the other type of driver (voltage controlled, e.g. "Saturated"), it will appear dim because it is expecting full voltage/current to flow
for the entire duration of the pulse width.
Let's move to the other situation where a noid light flashes normally when it should be dim. This could occur if a more sensitive n o id l igh t is
used on a higher voltage/amperage circuit that was weakened enough to cause problems (but not outright broken). A circuit with an actual
problem would thus appear normal.
Let's look at why. A noid light does not come close to consuming as much amperage as an injector solenoid. If there is a partial driver failure
or a minor voltage drop in the injector circuit, there can be adequate amperage to fully operate the noid light BUT NOT ENOUGH TO
OPERATE THE INJECTOR.
If this is not clear, picture a battery with a lot of corrosion on the terminals. Say there is enough corrosion that the starter motor will not
operate; it only clicks. Now imagine turning on the headlights (with the ignition in the RUN position). You find they light normally and are
fully bright. This is the same idea as noid light: There is a problem, but enough amp flow exists to operate the headlights ("noid light"), but not
the starter motor ("injector").
How do you identify and avoid all these situations? By using the correct type of noid light. This requires that you understanding the types of
injector circuits that your noid lights are designed for. There are three. They are:
Systems with a voltage controlled injector driver. Another way to say it: The noid light is designed for a circuit with a "high" resistance
injector (generally 12 ohms or above).
Systems with a current controlled injector driver. Another way to say it: The noid light is designed for a circuit with a low resistance
injector (generally less than 12 ohms) without an external injector resistor.
Systems with a voltage controlled injector driver and an external injector resistor. Another way of saying it: The noid light is designed
for a circuit with a low resistance injector (generally less than 12 ohms) and an external injector resistor.
If you are not sure which type of circuit your noid light is designed for, plug it into a known good car and check out the results. If it flashes
normally during cranking, determine the circuit type by finding out injector resistance and if an external injector resistor is used. You now
know enough to identify the type of injector circuit. Label the noid light appropriately.
Next time you need to use a noid light for diagnosis, determine what type of injector circuit you are dealing with and select the appropriate
noid light.
Of course, if you suspect a no-pulse condition you could plug in any one whose connector fit without fear of misdiagnosis. This is because it is
unimportant if the flashing light is dim or bright. It is only important that it flashes.
In any cases of doubt regarding the use of a noid light, a lab scope will overcome all inherent weaknesses.
OVERVIEW OF DVOM
A DVOM is typically used to check injector resistance and available voltage at the injector. Some techs also use it check injector on-time
either with a built-in feature or by using the dwell/duty function.
There are situations where the DVOM performs these checks dependably, and other situations where it can deceive you. It is important to be
aware of these strengths and weaknesses. We will cover the topics above in the following text.
Checking Injector Resistance
If a short in an injector coil winding is constant, an ohmmeter will accurately identify the lower resistance. The same is true with an open
winding. Unfortunately, an intermittent short is an exception. A faulty injector with an intermittent short will show "good" if the ohmmeter
cannot force the short to occur during testing.
Alcohol in fuel typically causes an intermittent short, happening only when the injector coil is hot and loaded by a current high e n o u gh t o
jump the air gap between two bare windings or to break down any oxides that may have formed between them.
When you measure resistance with an ohmmeter, you are only applying a small current of a few milliamps. This is nowhere near enough to
load the coil sufficiently to detect most problems. As a result, most resistance checks identify intermittently shorted injectors as being normal.
There are two methods to get around this limitation. The first is to purchase an tool that checks injector coil windings under full load. The
Kent-Moore J-39021 is such a tool, though there are others. The Kent-Moore costs around $240 at the time of this writing and works on many
different manufacturer's systems.
The second method is to use a lab scope. Remember, a lab scope allows you to see the regular operation of a circuit in real time. If an injector
is having an short or intermittent short, the lab scope will show it.
Checking Available Voltage At the Injector
Verifying a fuel injector has the proper voltage to operate correctly is good diagnostic technique. Finding an open circuit on the feed circuit
like a broken wire or connector is an accurate check with a DVOM. Unfortunately, finding an intermittent or excessive resistance problem with
a DVOM is unreliable.
Let's explore this drawback. Remember that a voltage drop due to excessive resistance will only occur when a circuit is operating? Since the
injector circuit is only operating for a few milliseconds at a time, a DVOM will only see a potential fault for a few milliseconds. The remaining
90+% of the time the unloaded injector circuit will show normal battery voltage. NOTE:Som e noid lights can m eet both the second and third categories sim ultaneously.
Page 2 of 19 MITCHELL 1 ARTICLE - GENERAL INFORMATION Waveforms - Injector Pattern Tutorial
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