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Alternator - W/internal Fan Ford Explorer I

Charging System 5 illustrations ~1205 words

DESCRIPTION

Major components of the Motorcraft Integral Alternator-Regulator (IAR) system with internal fan are end frames, rotor, stator, rectifier assembly and electronic voltage regulator mounted on the rear of the alternator. (Scheme 1)

Scheme 1

Scheme 1: DESCRIPTION
Scheme 1: DESCRIPTION

BELT TENSION

Check condition and tension of alternator drive belt prior to performing any on-vehicle charging system tests. Replace belt and/or repair tensioner mechanism if necessary. Belt tension is okay if belt length indicator is within limit marks on tensioner.

TROUBLE SHOOTING

Note. See TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

BASE VOLTAGE TEST

Note. Prior to performing BASE VOLTAGE TEST, turn on headlights for 10-15 seconds to remove any surface charge from battery.

Ensure battery is in good condition and fully charged. Connect negative voltmeter lead to negative battery post, and positive voltmeter lead to positive battery post. Record battery voltage. This reading is base voltage.

NO-LOAD TEST

  1. Connect tachometer to engine. Start engine and operate at 1500 RPM with no electrical load (foot off brake and doors closed).
  2. Measure voltage when needle stops moving. This may require waiting a few minutes. Voltmeter reading should increase, but not more than 3 volts greater than base voltage. See «BASE VOLTAGE TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__base-voltage-test) .
  3. If the voltage increases at least .5 volt over base voltage, go to «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test) . If voltage increase is more than 3 volts, proceed to «HIGH VOLTAGE TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan) . If there is no voltage increase, or voltage increase is less than .5 volt, proceed to «LOW VOLTAGE TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__low-voltage-test) .

LOAD TEST

  1. Connect tachometer to engine. Start engine. Load alternator by switching heater/air conditioner blower motor to high position and headlights to high beam. Increase engine speed to 2000 RPM.
  2. Voltmeter should indicate at least .5 volt more than base voltage. If voltage is within specification, alternator operation is normal. If volt-meter indicates high voltage (3 volts greater than base voltage), go to HIGH VOLTAGE TEST. If voltmeter does not indicate at least .5 volt greater than base voltage, go to LOW VOLTAGE TEST.

Scheme 2

Scheme 2: HIGH VOLTAGE TEST
Scheme 2: HIGH VOLTAGE TEST

Scheme 3

Scheme 3
Scheme 3
  1. Set ignition switch to RUN position (engine off). Measure voltage at alternator output connection, at starter relay and at regulator terminal "A" screw head. (Scheme 2)
  2. A voltage difference between 2 locations of greater than.5 volt, indicates high resistance in circuit "A" wiring. Repair circuit "A" and rerun NO-LOAD TEST and LOAD TEST.
  3. If high voltage condition still exists, inspect alternator and regulator ground screws for looseness. Tighten grounding screws and repeat NO-LOAD TEST and LOAD TEST. (Scheme 3)
  4. If high voltage condition still exists, connect voltmeter negative lead to ground. Ensure ignition is off. Measure voltage at regulator terminal "A" screw head and then at regulator terminal "F" screw head. Different voltages at 2 screw heads indicates a malfunctioning regulator grounded brush lead or a grounded rotor coil. Replace alternator/regulator assembly.
  5. If same voltage (battery voltage) exists at both regulator terminal "A" and "F" screw heads, there is no short to ground through alternator field/brushes. Replace regulator and repeat «NO-LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__no-load-test) and «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test).

LOW VOLTAGE TEST

  1. Disconnect wiring harness connector from regulator. Measure resistance regulator terminal "A" and "F" screw heads. If resistance is greater than 2.4 ohms, go to next step. If resistance is less than 2.4 ohms, replace alternator. Repeat «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test).
  2. Reconnect wiring harness to regulator. Measure voltage at terminal "A" screw head. If battery voltage exists, go to next step. If battery voltage does not exist, repair circuit "A" wiring. Repeat «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test).
  3. Ensure ignition is off. Measure voltage at terminal "F" screw head. If battery voltage exists, go to next step. If battery voltage does not exist, repair open field circuit in alternator. Repeat «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test).
  4. Set ignition switch to RUN position (engine off). Measure voltage at terminal "F" screw head. If voltage is 2 volts or less, go to next step. If voltage is greater than 2 volts, go to «REGULATOR CIRCUIT "S" TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__regulator-circuit-s-test). If circuit "I" test is normal, replace regulator and repeat «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test).
  5. Perform LOAD TEST while measuring voltage at alternator output terminal. If voltage increase is greater than.5 volts above base voltage, repair wiring harness between alternator output terminal and starter relay battery terminal. If voltage increase is not greater than.5 volts above base voltage, go to next step.
  6. Perform «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test) while measuring voltage drop between battery positive terminal and terminal "A" of regulator (with wiring harness connector connected). If voltage drop does not exceed.5 volt, go to next step. If voltage drop exceeds.5 volt, repair wiring harness between alternator regulator and starter relay.
  7. Connect a jumper wire from alternator rear housing to regulator terminal "F" screw. (Scheme 4) Perform LOAD TEST while measuring voltage at alternator output terminal. If voltage increases.5 volt or more greater than base voltage, replace regulator. If voltage increase is not at least.5 volt greater than base voltage, replace alternator.

Scheme 4

Scheme 4
Scheme 4

REGULATOR CIRCUIT "S" TEST

  1. Unplug wiring harness connector from regulator. Connect jumper wire between regulator terminal "A" and terminal "A" of harness connector. Connect a jumper wire between regulator terminal "F" screw head and ground on alternator rear housing. (Scheme 5)
  2. Start and idle engine. Measure voltage at terminal "S" and at terminal "I" of wiring harness connector. Voltage at terminal "S" should be approximately half that at terminal "I". If voltages are normal, remove jumper wires. Replace regulator. Repeat LOAD TEST.
  3. If voltage at terminal "S" is not approximately half that at terminal "I", repair faulty wiring circuit or replace alternator. Reconnect regulator harness. Repeat «LOAD TEST»(/ford/explorer/i-1990-1994/remont/charging-system/#alternator-winternal-fan__load-test) to confirm repair.

Scheme 5

Scheme 5
Scheme 5

FIELD CIRCUIT DRAIN TEST

Note. Connect voltmeter negative lead to alternator rear housing for all the following voltage readings.

  1. Turn ignition off. Measure voltage at terminal "F" screw head. (Scheme 5) If voltage is less than battery voltage, go to next step. If battery voltage is indicated, system is functioning properly. Further testing is not needed.
  2. Measure voltage at terminal "I" of wiring harness connector. If voltage is zero, go to next step. If voltage is not zero, repair short to voltage in circuit "I".
  3. Measure voltage at terminal "S" of wiring harness connector (with connector connected to regulator). If voltage is not zero, go to next step. If voltage is zero, replace regulator.
  4. Unplug wiring harness connector from regulator. Measure voltage at terminal "S" of harness connector. If voltage is not zero, repair short to voltage in wiring harness. If voltage is zero, replace alternator.

REMOVAL & INSTALLATION

CAUTION: When battery is disconnected, vehicle computer and memory

systems may lose memory data. Driveability problems may

exist until computer systems have completed a relearn cycle.

See COMPUTER RELEARN PROCEDURES article in the GENERAL

INFORMATION Section before disconnecting battery.

Disconnect battery negative cable. Remove snow/ice shield. Remove fresh air inlet duct. Disconnect wiring from alternator. Remove connector bracket. Disengage drive belt. Remove attachment bolts and alternator. Reverse removal procedure to install.

BENCH TESTING

Manufacturer states that alternator is serviced only as an assembly.

OVERHAUL

Manufacturer states that alternator is serviced only as an assembly.

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