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Alternator & Regulator Mazda RX-7 FC

Charging System 7 illustrations ~1638 words

DESCRIPTION

Mitsubishi alternators are conventional 3-phase, self-rectifying type units containing 6 diodes (3 positive and 3 negative) which are used to rectify current. A case-mounted Integrated Circuit (IC) regulator is used on all models.

PRELIMINARY CHECK

Check alternator wire harness connections and drive belt tension. Battery must be fully charged prior to beginning test. Wait at least 30 seconds after starting engine before measuring voltage.

Scheme 1

Scheme 1: 626 & MX-6
Scheme 1: 626 & MX-6

Scheme 2

Scheme 2
Scheme 2
  1. Disconnect alternator 2-pin connector. Install an adapter harnesses and checker lamp. (Scheme 1) Connect Red clip of adapter harness to positive battery terminal. Ensure Red and Green light is on. Start engine and ensure both lights go out.
  2. Connect a 65-amp or larger ammeter between disconnected wire and terminal "B". (Scheme 2) Turn on headlights and accessories. Depress brake pedal. Start engine and ensure output current is 65 amps or more when engine is 2500-3000 RPM. Do not ground "B" terminal.
  3. Turn off accessories and release brake pedal. Ensure output current is 5 amps or more when engine speed is 25000-3000 RPM. Using a voltmeter, check voltage between "S" terminal and ground. Voltage should be 14.1-14.7 volts. Turn ignition on. Using a voltmeter between terminal "L" and ground, 1-5 volts should be present.
  4. With ignition on and accessories off, attach voltmeter between terminal "S" and ground. Battery voltage should be present.

Alternator Quick Check (B2200, B2600 & 929)

Disconnect "R" and "L" terminals from alternator. (Scheme 3) Install checker lamp and adapter harness. (Scheme 4) Connect adapter harness Red lead to battery positive. Red and Green light should turn on. Start engine and ensure both lights go out. If lights go out, perform IC REGULATOR POWER SOURCE TEST in this article. If lights do not go out, perform OUTPUT VOLTAGE TEST in this article.

Scheme 3

Scheme 3: Alternator Quick Check (B2200, B2600 & 929)
Scheme 3: Alternator Quick Check (B2200, B2600 & 929)

Scheme 4

Scheme 4
Scheme 4

IC Regulator Power Source Test (B2200, B2600 & 929)

Ensure ignition is off. Disconnect "R" terminal connector from alternator. Turn ignition on. Using a voltmeter, measure voltage between terminal "R" and ground. If battery voltage is not present, repair or replace wire harness. If battery voltage is present, perform OUTPUT CURRENT TEST in this article

Output Current Test (B2200, B2600 & 929)

Ensure ignition is off. Disconnect negative battery cable. Disconnect wire at the alternator "B" terminal. Connect an ammeter (60 amps or less) between alternator terminal "B" and the disconnected wire. Connect negative battery cable. Turn headlights and accessories on. Depress brake pedal. Start engine. Increase engine speed to 2500-3000 RPM. Note amp readings. If 50 amps or more are present, alternator is okay. If less than 50 amps are present, perform OUTPUT VOLTAGE TEST in this article.

Output Voltage Test (B2200, B2600 & 929)

  1. Ensure ignition and accessories are off. Apply a charge to the battery until charger indicator shows less than a 5 amp charge rating. If charge rating cannot be achieved, replace battery with a fully charged one.
  2. Disconnect negative battery cable. Disconnect wire at the alternator "B" terminal. Connect an ammeter (60 amps or less) between alternator terminal "B" and the disconnected wire. Connect negative battery cable. Start engine.
  3. Increase engine speed to 2500 RPM. If less than 5 amps are present, perform ROTOR COIL TEST in this article. If more than 5 amps are present, turn off ignition and disconnect negative battery cable. Reconnect "B" terminal wire to alternator. Connect negative battery cable and start engine.
  4. Using a voltmeter, backprobe one lead to terminal "L" (connector attached to alternator). Ground the other voltmeter lead. Increase engine speed to 2500 RPM. If voltmeter shows 14.2-15.2 volts at 68°F (20°C) perform ROTOR COIL TEST in this article.
  5. If voltmeter shows less than 14.2 or more than 15.2 volts at 68°F (20°C), check as follows: A) - Fault between terminal "B" wire and positive battery cable. Repeat IC REGULATOR POWER SOURCE TEST in this article. B) - Poor negative battery cable connection. Repeat IC REGULATOR POWER SOURCE TEST in this article. C) - Fault between terminal "R", "L" connector and positive battery cable. Repeat OUTPUT VOLTAGE TEST in this article. D) - Defective stator and/or diodes. See BENCH TESTING in this article.

Scheme 5

Scheme 5: Rotor Coil Test (B2200, B2600 & 929)
Scheme 5: Rotor Coil Test (B2200, B2600 & 929)
  1. Ensure ignition is off. Disconnect negative battery cable. Disconnect terminals "B", "L" and "R" connectors from alternator. Using an ohmmeter, measure resistance between "L" and "F" terminals on the alternator. (Scheme 5)
  2. If 3-6 ohms is present, perform ALTERNATOR "L" TERMINAL VOLTAGE TEST in this article. If other than 3-6 ohms is present, rotate pulley and check resistance again. If 3-6 ohms is present now, perform ALTERNATOR "L" TERMINAL VOLTAGE TEST in this article. If other than 3-6 ohms is still present, check rotor and brush. See BENCH TESTING in this article.

Alternator "L" Terminal Voltage Test (B2200, B2600 & 929)

Ensure alternator connectors are connected to alternator and negative battery cable is reconnected. Turn ignition on. Using a voltmeter, backprobe on lead to terminal "L" and other lead to a ground. If 1-3 volts is present, no problem exists. If over 3 volts is present, IC regulator and/or rotor is defective. See BENCH TESTING in this article.

Scheme 6

Scheme 6: RX-7
Scheme 6: RX-7
  1. Disconnect negative battery cable. Disconnect "B" terminal from alternator. Connect a 60 amp or larger ammeter between disconnect wire and terminal "B". (Scheme 6) Reconnect negative battery cable. Turn on headlights and accessories. Depress brake pedal. Start engine and increase engine speed to 2500-3000 RPM. Do not ground terminal "B". If amperage is 55 amps or more, alternator is okay.
  2. If less than 55 amps are present, turn ignition and accessories off. Charge battery until charging rate is less than 5 amps. If charging rate cannot be achieved, install a fully charged battery.
  3. Check amperage with ammeter between terminal "B" and ground. Start engine and increase engine speed to 2500 RPM. If less than 5 amps is present, proceed to step 6). If 5 amps or more is present, proceed to next step.
  4. Turn ignition off and disconnect negative battery cable. Connect alternator wiring connectors. Connect negative battery cable. Start engine and increase engine speed to 2500 RPM. Using a voltmeter, measure voltage between terminal "L" and ground.
  5. If voltage is 14.4-15.0 volts, proceed to next step. If voltage is less than 14.4 or more than 15.0 volts, a poor connection may be present between terminal "B" and positive battery cable, at negative cable, between 2-prong connector ("L" and "R") and positive battery cable or a problem may be present in stator coil and/or diodes.
  6. Turn ignition off. Disconnect terminal "R" connector from alternator. Turn ignition on and measure voltage between "R" terminal and ground. If battery voltage is present, proceed to next step. If battery voltage is not present, there is a problem with the wiring harness.
  7. Turn ignition off and disconnect negative battery cable. Disconnect "B" terminal from alternator. Using an ohmmeter, check resistance between alternator "L" and "F" terminals. If resistance is 2-4 ohms proceed to next step. If not 2-4 ohms, rotate alternator pulley and check resistance again. If resistance still is not 2-4 ohms, rotor coil or brush is defective.
  8. Ensure ignition is off and all disconnect connectors are reconnected. Turn ignition on. Measure voltage between alternator "L" terminal and ground. If voltage is 1-3 volts, alternator is okay. If not, regulator or rotor coil is defective.

B2200, B2600, RX-7 & 929

  1. Turn off accessories and disconnect negative battery cable. Disconnect terminal "B" connector. Connect a 60-amp or larger ammeter between wire and terminal "B". Charge battery until the charging rate is less than 5 amps. If charging rate cannot be achieved, replace battery with a fully charged battery.
  2. Connect negative battery cable. Start engine and increase engine speed to 2500 RPM. If more than 5 amps are present, alternator is okay. If not, reconnect alternator "B" terminal. Using a voltmeter, measure terminal "L" voltage at 2500 RPM.
  3. On RX-7 models, if more than 15 volts are present, alternator is defective. If 14.4-15.0 volts are present, alternator is okay.
  4. On all other models, if more than 15.2 volts are present, alternator is defective. If 14.2-15.2 volts are present, alternator is okay.

RX-7

  1. Turn ignition off and disconnect negative battery cable. Disconnect terminal "R" connector from alternator. Connect negative battery cable and turn ignition on. Measure voltage between "R" terminal and ground. If less than battery voltage is present, wiring harness is defective. If battery voltage is present, proceed to next step.
  2. Turn ignition off and disconnect negative battery cable. Disconnect terminal "B" connector from alternator. Using an ohmmeter, check resistance between alternator "L" and "F" terminals. If 2-4 ohms are present, IC regulator is defective. If other than 2-4 ohms are present, rotor coil or brush is defective.

Diode Assembly

  1. Check each diode with ohmmeter in both directions. If diodes show large resistance in one direction and small resistance in other direction, diodes are normal.
  2. If diodes show small resistance in both directions, it is shorted. If large resistance is shown in both directions, diode is open. If any diodes are defective, replace rectifier assembly.

Rotor

Check continuity across rotor slip rings. A reading of 2.0-2.6 ohms on B2200 and RX-7, must be obtained. On all other models, reading should be 3-4 ohms. If there is no continuity, replace rotor. Check continuity between individual slip rings and rotor core/shaft. If there is continuity, rotor coil or slip ring is grounded. Replace rotor.

Stator

Ensure no continuity exists between stator coil leads and stator core. Check continuity between leads of stator coil. If there is no continuity, replace stator.

Brushes

  1. Replace brushes if worn to limit line. Standard brush spring tension should be 12-16 oz. (340-453 g). Replace if less than 7 oz. (198 g) or if springs are corroded.
  2. To remove brushes from holder, unsolder pigtail from terminal. To replace, solder pigtail to terminal ensuring 1/4" of brush will be located in brush holder.

Scheme 7

Scheme 7: OVERHAUL
Scheme 7: OVERHAUL