1991 1999 ford explorer chilton User Manual

							
FIRING ORDERS
To avoid confusion, remove and tag the spark plug wires one at a time, for replacement.
If a distributor is not keyed for installation with only one orientation, it could have been removed previously
and rewired. The resultant wiring would hold the correct firing order, but could change the relative placement
of the plug towers in relation to the engine. For this reason it is imperative that you label all wires before
disconnecting any of them. Also, before removal, compare the current wiring with the accompanying
illustrations. If the current wiring does not match, make notes in your book to reflect how your engine is
wired.
1991-94 2.9L and 3.0L Engines Distributor rotation: Clockwise
FIRING ORDERS 211 
						

							2.3L, 2.5L Engines Distributorless ignition
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HOW TO USE THIS BOOK
212 FIRING ORDERS 
						

							1995-99 3.0L Engines Distributorless ignition
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HOW TO USE THIS BOOK
FIRING ORDERS 213 
						

							4.0L Engines Distributorless ignition
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HOW TO USE THIS BOOK
214 FIRING ORDERS 
						

							1996-99 5.0L Engines Distributorless ignition
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Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning. HOW TO USE THIS BOOK
FIRING ORDERS 215 
						

							
CHARGING SYSTEM
General Information
The charging system is a negative (-) ground system which consists of an alternator, a regulator, a charge
indicator, a storage battery, wiring connecting the components, and fuse link wire.
The alternator is belt-driven from the engine. Energy is supplied from the alternator/regulator system to the
rotating field through two brushes to two slip-rings. The slip-rings are mounted on the rotor shaft and are
connected to the field coil. This energy supplied to the rotating field from the battery is called excitation
current and is used to initially energize the field to begin the generation of electricity. Once the alternator
starts to generate electricity, the excitation current comes from its own output rather than the battery.
The alternator produces power in the form of alternating current. The alternating current is rectified by 6
diodes into direct current. The direct current is used to charge the battery and power the rest of the electrical
system.
When the ignition key is turned ON, current flows from the battery, through the charging system indicator
light on the instrument panel, to the voltage regulator, and to the alternator. Since the alternator is not
producing any current, the alternator warning light comes on. When the engine is started, the alternator begins
to produce current and turns the alternator light off. As the alternator turns and produces current, the current is
divided in two ways: one part to the battery to charge the battery and power the electrical components of the
vehicle, and one part is returned to the alternator to enable it to increase its output. In this situation, the
alternator is receiving current from the battery and from itself. A voltage regulator is wired into the current
supply to the alternator to prevent it from receiving too much current, which, in turn, would cause it to
produce too much current. Conversely, if the voltage regulator does not allow the alternator to receive enough
current, the battery will not be fully charged and will eventually drain.
CHARGING SYSTEM 217 
						

							
Exploded view of the alternator. Note the fan is externally mounted, however, internal mount fans are also used
Click to enlarge
The battery is connected to the alternator at all times, whether the ignition key is turned ONor not. If the
battery were shorted to ground, the alternator would also be shorted. This would damage the alternator. To
prevent this, a fuse link is installed in the wiring between the battery and the alternator. If the battery is
shorted the fuse link melts, protecting the alternator.
Alternator Precautions
To prevent damage to the alternator and regulator, the following precautions should be taken when working
with the electrical system.
Never reverse the battery connections.
· 
Booster batteries for starting must be connected properly: positive-to-positive and
negative-to-ground.
· 
Disconnect the battery cables before using a fast charger; the charger has a tendency to force current
through the diodes in the opposite direction for which they were designed. This burns out the diodes.
· 
Never use a fast charger as a booster for starting the vehicle.
· 
Never disconnect the voltage regulator while the engine is running.
· 
Avoid long soldering times when replacing diodes or transistors. Prolonged heat is damaging to AC
generators.
· 
Do not use test lamps of more than 12 volts (V) for checking diode continuity.
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218 General Information 
						

							Do not short across or ground any of the terminals on the AC generator.
· 
The polarity of the battery, generator, and regulator must be matched and considered before making
any electrical connections within the system.
· 
Never operate the alternator on an open circuit. make sure that all connections within the circuit are
clean and tight.
· 
Disconnect the battery terminals when performing any service on the electrical system. This will
eliminate the possibility of accidental reversal of polarity.
· 
Disconnect the battery ground cable if arc welding is to be done on any part of the vehicle.
· 
Alternator
TESTING
General Information
There are many possible ways in which the charging system can malfunction. Often the source of a problem is
difficult to diagnose, requiring special equipment and a good deal of experience. This is usually not the case,
however, where the charging system fails completely and causes the dash board warning light to come on or
the battery to discharge. To troubleshoot a complete system failure, only two pieces of equipment are needed:
a test light, to determine that current is reaching a certain point and a current indicator (ammeter), to
determine the direction of the current flow and its measurement in amps. This test works under three
assumptions:
The battery is known to be good and fully charged.
1. 
The alternator belt is in good condition and adjusted to the proper tension.
2. 
All connections in the system are clean and tight.
3. 
In order for the current indicator to give a valid reading, the vehicle must be equipped with battery
cables which are of the same gauge size and quality as original equipment battery cables.
Before commencing with the following tests, turn off all electrical components on the vehicle. Make sure the
doors of the vehicle are closed. If the vehicle is equipped with a clock, disconnect the clock by removing the
lead wire from the rear of the clock.
Battery No-Load Test Ensure that the ignition switch is turned OFF.
1. 
Connect a tachometer to the engine by following the manufacturers instructions.
2. 
Using a Digital Volt Ohmmeter (DVOM) measure the voltage across the positive (+) and negative (-)
battery terminals. Note the voltage reading for future reference.
3. 
Ensure that all electrical components on the vehicle are turned off. Be sure the doors of the vehicle are closed.
If the vehicle is equipped with a clock, disconnect the clock by removing the lead wire from the rear of the
clock.
Start the engine and have an assistant run it at 1500 rpm.
4. 
Read the voltage across the battery terminals again. The voltage should now be between 14.1-14.7
volts. If the voltage increase is less than 2.5 volts over the base voltage measured in Step 3, perform
the Battery Load test.
1. 
If there was no voltage increase, or the voltage increase was greater than 2.5 volts, perform
the Alternator Load and No-Load tests.
2. 
5.  HOW TO USE THIS BOOK
Alternator Precautions 219 
						

							
Battery Load Test
With the engine running, turn the air conditioner ON (if equipped) or the blower motor on high speed
and the headlights on high beam.
1. 
Have your assistant increase the engine speed to approximately 2000 rpm.
2. 
Read the voltage across the battery terminals again. If the voltage increase is 0.5 volts over the base voltage measured in Battery No-Load test
Step 3, the charging system is working properly. If your problem continues, there may be a
problem with the battery.
1. 
If the voltage does not increase as indicated, perform the Alternator Load and No-Load tests.
2. 
3. 
Alternator Load Test WARNING
Do NOT use a normal Digital Volt Ohmmeter (DVOM) for this test; your DVOM will be destroyed by the
large amounts of amperage from the cars battery. Use a tester designed for charging system analysis, such as
the Rotunda Alternator, Regulator, Battery and Starter Motor Tester 010-00725 (ARBST) or equivalent.
Switch the tester to the ammeter setting.
1. 
Attach the positive (+) and negative (-) leads of the tester to the battery terminals.
2. 
Connect the current probe to the B+terminal on the alternator.
3. 
Start the engine and have an assistant run the engine at 2000 rpm. Adjust the tester load bank to
determine the output of the alternator. Alternator output should be within ten percent of the
alternators output rating; if so, continue with the Alternator No-Load test. If the output is not within
ten percent of the alternators output rating, there is a problem in the charging system. Have the
system further tested by a Ford qualified automotive technician.
4. 
Alternator No-Load Test Using the same tester as in the Alternator Load Test, switch the tester to the voltmeter function.
1. 
Connect the voltmeter positive (+) lead to the alternator B+terminal and the negative (-) lead to a
good engine ground.
2. 
Turn all of the electrical accessories off and shut the doors.
3. 
While an assistant operates the engine at 2000 rpm, check the alternator output voltage. The voltage
should be between 13.0-15.0 volts. If the alternator does not produce voltage within this range there
is a problem in the charging system. Have the system further tested by a Ford qualified automotive
technician.
4. 
REMOVAL & INSTALLATION Disconnect the negative battery cable.
1. 
Remove the accessory drive belt.
2.  HOW TO USE THIS BOOK
220 TESTING 
						

							After disconnecting the battery and removing the drive belt, unplug the single wire connector ...
... then the multi-wire connector from the back of the alternator-integral regulator units lack the single wire
If the push-on connectors are difficult to remove, use a small pick to disengage the connector latch
HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 221