Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Alternator

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ALTERNATOR PRECAUTIONS



Because of the nature of alternator design, special care must be taken when servicing the charging system:



Battery polarity should be checked before any connections, such as jumper cables or battery charger leads, are made. Reversed battery connections will damage the diode rectifiers.
 
The battery must never be disconnected while the alternator is running, because the regulator will be ruined.
 
Always disconnect the battery ground cable before replacing the alternator.
 
Do not attempt to polarize an alternator.
 
Do not short across or ground any alternator terminals.
 
Always disconnect the battery ground cable before removing the alternator output cable, whether the engine is running or not.
 
If electric arc welding equipment is to be used on the car, first disconnect the battery and alternator cables. Never start the engine with the electric arc welding equipment attached.
 
If the battery is to be quick-charged, disconnect the positive cable from the battery.
 
Do not use any type of high voltage resistance tester in the electrical circuits of the car, while the alternator is connected.
 

TESTING



For these tests, you will need an ammeter and, except for the 1980 GLC, a voltmeter.

1980 GLC

See Figure 1

This test assumes that you know the battery is undercharged, and that the alternator drive belt and basic wiring are in working condition. If the specific gravity of the battery cells indicate inadequate charging (is less than 1.260) and the vehicle has been driven in a normal manner (without too many extremely short trips), the alternator is not charging properly.



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Fig. Fig. 1: Connect an ammeter in series between the alternator's B terminal and the wire, then unplug the alternator's multi-connector and attach jumper wires, as shown

  1. Disconnect the wire from the B terminal of the alternator, and connect an ammeter between the B terminal and the wire.
  2.  

Refer to the accompanying illustration, as necessary, for terminal designations.

  1. Disconnect the alternator's multi-connector and attach jumper wires, as shown.
  2.  
  3. Start the engine and run it at 2,000 rpm (you can use a dwell/tachometer to measure rpm). Read the ammeter, and note the reading. Then, pull the wire off the female F terminal and connect it to the female A terminal just long enough to get a current reading. Shut off the engine.
  4.  
  5. If the amperage reading increases significantly, the trouble is in the regulator; if it remains exactly the same, the trouble is in the alternator.
  6.  

1980-82 626

See Figure 2

  1. With the ignition switch OFF , connect the voltmeter between the R terminal and ground, then read the voltage. Do the same for the L terminal. If there is voltage at either terminal, the alternator is defective.
  2.  



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Fig. Fig. 2: Connect the voltmeter and ammeter as shown to test alternator output-1981-85 GLC and 1980-85 626 (except diesel)

  1. With the voltmeter still connected to the L terminal, turn the ignition switch ON and read the voltmeter. Note the reading, then check the voltage across the battery terminals. L terminal voltage should be 1-3 volts DC. If there is no voltage, the alternator or associated wiring is bad. If the voltage is close to the battery's voltage, connect a jumper wire between the F terminal and ground. If the voltage at the L terminal drops lower than the battery voltage, this indicates that the IC regulator may be faulty.
  2.  

The F terminal is neither exposed on the surface of the alternator rear bracket, nor marked for its location. It is located at a depth of 0.79 in. (20mm) in a hole near the mark of B terminal.


WARNING
Do not start the engine with the connector for the L and R terminals unplugged, and do not ground the L terminal while the engine is running.

  1. Start the engine and turn on the headlights. Gradually increase the engine speed as you read the output voltage and current. If output voltage is higher than battery voltage, and there is output current, the alternator is operating satisfactorily.
  2.  

On 1982 models, you can go a step further and check the no-load adjustment voltage as follows:

  1. With the battery fully charged, connect a voltmeter between the battery's positive terminal and ground. Connect a voltmeter between the L terminal on the rear of the alternator and ground. Connect an ammeter between the alternator's B terminal and the battery's positive terminal. Jumper the ammeter with a heavy-gauge wire (as illustrated by the dotted line) while starting the engine, then remove the jumper. Run the engine at 2,000-2,500 rpm (check rpm with a dwell/tach). This will turn the alternator 5,000 rpm. The ammeter should read less than 5 amps, and the voltmeter 14.1-14.7 volts DC. Now, turn on the lights. If the alternator responds by putting out increased amperage, and the voltage is higher than the battery voltage, it is functioning properly.
  2.  

1981-85 GLC and 1983-85 626
EXCEPT DIESEL

See Figures 2, 3, 4 and 5

  1. With the ignition switch OFF , connect the voltmeter between the L terminal and ground, then read the voltage. If there is any voltage, the alternator is defective.
  2.  
  3. With the voltmeter still connected to the L terminal, turn the ignition switch ON and read the voltmeter. If the reading is 0 volts, there is probably a malfunction in the alternator, but check the wiring first. If the voltage is close to the battery's voltage, connect a jumper wire between the F terminal and ground. If the voltage at the L terminal drops lower than the battery voltage, this indicates a malfunction of the IC regulator.
  4.  


WARNING
Do not start the engine with the connector for the L and R terminals unplugged, and do not ground the L terminal while the engine is running.



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Fig. Fig. 3: Alternator terminal connections-1981-85 GLC



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Fig. Fig. 4: Alternator terminal connections-1983-85 626 (except diesel)



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Fig. Fig. 5: Before checking the no-load adjustment voltage, temporarily install a shunt (as indicated by the dotted line) to short circuit the ammeter during engine start-up-1983-85 626

  1. Start the engine and turn on the headlights. Gradually increase the engine speed as you read the output voltage and current. If output voltage is higher than battery voltage, and there is output current, the alternator is operating satisfactorily.
  2.  
  3. Check the no-load adjustment voltage after installing a shunt to protect the ammeter during start-up, as illustrated. With the battery fully charged, connect a voltmeter between the battery's positive terminal and ground. Connect a voltmeter between the L terminal on the rear of the alternator and ground. Connect an ammeter between the alternator's B terminal and the battery's positive terminal. Jumper the ammeter with a heavy-gauge wire (as illustrated by the dotted line) while starting the engine, then remove the jumper. Run the engine at 2,000-2,500 rpm (check rpm with a dwell/tach). This will turn the alternator 5,000 rpm. The ammeter should read less than 5 amps, and the voltmeter 14.4-15.0 volts DC (14.1-14.7 volts DC for the 1981-83 GLC). Now, turn on the lights. If the alternator responds by putting out increased amperage, and the voltage is higher than the battery voltage, it is functioning properly.
  4.  

1985 626 DIESEL

See Figures 6, 7 and 8

  1. With the ignition switch OFF , connect the voltmeter between the L terminal and ground, then read the voltage. If there is voltage at the terminal, the alternator is defective.
  2.  
  3. Turn the ignition switch ON and read the voltmeter. If the reading is 0 volts, there is probably a malfunction in the alternator, but check the wiring first. If the voltage is near the battery voltage, connect a jumper wire between the F terminal and ground. If the voltage at the L terminal drops lower than the battery voltage, this indicates a malfunction of the IC regulator.
  4.  



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Fig. Fig. 6: Alternator terminal connections-1985 626 diesel



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Fig. Fig. 7: Location of the F terminal on the 626 diesel alternator



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Fig. Fig. 8: Connect the voltmeter and ammeter as shown to test alternator output-1985 626 diesel

  1. Disconnect the negative battery cable. Connect an ammeter and voltmeter, as shown in the illustration. Then, reconnect the negative battery cable.
  2.  


WARNING
Do not start the engine with the connector for the L and R terminals unplugged, and do not ground the L terminal while the engine is running.

  1. Start the engine and turn on the headlights. Gradually increase the engine speed as you read the output voltage and current. If output voltage is higher than battery voltage, and there is output current, the alternator is operating satisfactorily.
  2.  

1986-87 323 and 1986 626

See Figures 9 and 10

Steps 1-8 should be followed if the battery constantly discharges. If the battery overcharges, proceed to Step 9.

  1. Start the engine and allow it to idle. Disconnect the alternator B terminal wire and connect an ammeter with a capacity of 60 amps or more between the wire and the terminal.
  2.  


CAUTION
Make connections carefully to avoid grounding the B terminal, which would burn out the alternator.

  1. Turn headlights and all accessories on.
  2.  
  3. Speed the engine up until it is turning 2,500-3,000 rpm. Read the output on the ammeter. Compare the reading with the nominal output shown on the Alternator and Regulator Specifications chart. On the 323s, if the output is 90% or more of the nominal indicated output, the alternator is okay. On the 1986 626, a minimum output of 51 amps is normal. If the current reading meets or exceeds the appropriate minimum level, turn off the headlights and accessories, and shut off the engine, then remove the ammeter and reconnect the alternator wire to terminal B . However, if the current reading does not meet the applicable minimum level, proceed with the following steps.
  4.  



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Fig. Fig. 9: Alternator terminal locations for the 1986 323



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Fig. Fig. 10: Alternator terminal locations for the 1986 626

  1. Turn off all lights and electrical accessories. Charge the battery until the charging rate is less than 5 amps at idle or replace the battery with one that is fully charged, if available. Then, read the ammeter at 2,500 rpm. If the reading is now more than 5 amps, there is a short (ground) somewhere in the vehicle wiring. If the indication is still less than 5 amps, proceed with the next step.
  2.  
  3. This step should be performed with the car at a normal room temperature of about 68°F (20°C). Disconnect the ammeter and reconnect the alternator wire to terminal B . Pull the R-L connector out just slightly, so you can get the probe of a voltmeter in to read the voltage while the connection is maintained. Connect a voltmeter to the L terminal of the alternator and to the alternator housing (ground). Accelerate the engine to 2,500 rpm and read the voltage. If the reading is 14.4-15.0 volts DC, the problem is in the alternator's stator coil and/or diodes. If it is less than 14.4 volts DC, proceed with the next step.
  4.  
  5. Unplug the R-L connector from the alternator terminals. Connect a voltmeter between the female R terminal (coming from the wiring harness) and the alternator housing or other ground. Then, turn the ignition switch ON and measure the voltage. If it is equal to the battery's voltage, proceed to the next step. If the measured voltage is lower, correct the problem in the wiring harness.
  6.  
  7. Turn the ignition switch OFF . Disconnect the wire from the B terminal of the alternator. Measure the resistance between the L and F terminals with an ohmmeter. The resistance should be 3-6 ohms. If resistance is not within this range, the problem is in the field coil (rotor) or slip ring, and the alternator must be replaced, or disassembled and repaired. If resistance is 3-6 ohms, proceed with the following steps.
  8.  
  9. Reconnect the B terminal connector to the alternator. Turn the ignition switch ON . Pull the R-L connector out just slightly, so you can get the probe of a voltmeter in to read the voltage while the connection is maintained. Measure the voltage at the L terminal prong. If it is over 3.0 volts DC, the problem is in the regulator. If it is 1.0-3.0 volts DC, the problem is in the stator coil and/or diodes.
  10.  

Perform the following steps only if the battery overcharges:

  1. Turn off all electrical loads. Run the test with the vehicle as close to 68°F (20°C) as possible. Disengage the wiring connector from the alternator's B terminal. Connect an ammeter with a minimum capacity of 60 amps between the wire and the alternator's B terminal. Start the engine and run it to charge the battery until the charging rate is less than 5 amps. (If you have a fully charged battery available, it will save time to install it in place of the present one.) Pull the R-L connector out just slightly, so you can get the probe of a voltmeter in to read the voltage while the connection is maintained. Run the engine at 2,500 rpm and measure the voltage at the L terminal prong. If the voltage is 14.4-15.0 volts DC, the alternator is okay. If it is over 15.0 volts DC, proceed with the next step. Turn the engine OFF .
  2.  
  3. Disengage the R connector at the alternator. Connect a voltmeter between the R connector and a good ground. Turn the ignition switch ON and measure the voltage at the connector. If the voltage is less than battery voltage, repair the wiring harness. If the voltage is equal to battery voltage, proceed with the next step.
  4.  
  5. Turn the ignition switch OFF , then disconnect the wire from the alternator's B terminal. Connect an ohmmeter and measure the resistance between the L and F terminals. If resistance is 3-6 ohms, the problem lies in the voltage regulator. If resistance is outside that range, the problem is in the field coil or slip ring.
  6.  

1987 626

See Figure 11

Steps 1-10 should be followed if the battery constantly discharges. If the battery overcharges, proceed to Step 11.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the alternator B terminal wire and connect an ammeter with a capacity of 60 amps or more between the wire and the terminal.
  4.  


CAUTION
Make connections carefully to avoid grounding the B terminal, which would burn out the alternator.

  1. Reconnect the negative battery cable.
  2.  
  3. Turn the headlights and all accessories on, then depress (and hold) the brake pedal.
  4.  
  5. Start the engine and idle it at 2,500-3,000 rpm. Read the output on the ammeter; it should be a minimum of 55 amps. (If the current reading meets or exceeds this level, the alternator is functioning normally. If the current reading does not meet this level, proceed with the following steps.)
  6.  
  7. Turn off all lights and accessories, and release the brake pedal. Charge the battery until the charging rate is less than 5 amps at idle or replace the battery with one that is fully charged, if available. Then, read the ammeter at 2,500 rpm. If the reading is now more than 5 amps, there is a short (ground) somewhere in the vehicle wiring. If the indication is still less than 5 amps, proceed with the next step.
  8.  



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Fig. Fig. 11: Alternator terminal connections-1987 626

  1. This step should be done with the car at a normal room temperature of about 68°F (20°C). Shut off the engine and disconnect the negative battery cable. Disconnect the ammeter and reconnect the alternator wire to terminal B . Reconnect the negative battery cable and restart the engine. Pull the R-L connector out just slightly, so you can get the probe of a voltmeter in to read the voltage while the connection is maintained. Connect a voltmeter to the L terminal of the alternator and to the alternator housing (ground). Accelerate the engine to 2,500 rpm and read the voltage. If the reading is less than 14.2 volts DC or more than 15.2 volts DC, there may be a problem in the alternator's field coil or diodes. (However, such a voltage reading could also stem from a poor connection between the B terminal and the positive battery cable, or from a poor connection of the negative battery cable. It could also result from a poor connection between the 2-pin R-L connector and the positive battery cable.) If the voltage reading is 14.2-15.2 volts DC, proceed with the next step.
  2.  
  3. Turn the ignition switch OFF and unplug the R-L connector from the alternator terminals. Connect a voltmeter between the female R terminal (coming from the wiring harness) and the alternator housing or other ground. Then, turn the ignition switch ON and measure the voltage. If it is equal to the battery's voltage, proceed to the next step. If the measured voltage is lower, correct the problem in the wiring harness.
  4.  
  5. Turn the ignition switch OFF , then disconnect the negative battery cable. Disconnect the wire from the B terminal of the alternator, as well as the R-L connector. Measure the resistance between the L and F terminals with an ohmmeter. The resistance should be 3-6 ohms. If resistance is not within this range, the problem is in the rotor coil or brush(es), and the alternator must be replaced or disassembled and repaired. If resistance is 3-6 ohms, proceed with the following steps.
  6.  
  7. Reconnect the wire to the alternator's B terminal. Loosely attach the R-L connector, so you can get the positive (+) probe of a voltmeter in to read the voltage while the connection is maintained. Turn the ignition switch ON . Connect the negative (-) probe of the voltmeter to the alternator housing or other ground, and measure the voltage at the L terminal prong. If it is over 3.0 volts DC, the problem is in the regulator. If it is 1.0-3.0 volts DC, the problem is in the stator coil and/or diodes.
  8.  

Perform the following steps only if the battery overcharges:

  1. Turn off all electrical loads. Perform this step with the vehicle as close to 68°F (20°C) as possible. Disconnect the negative battery cable and the wire from the alternator's B terminal. Connect an ammeter with a minimum capacity of 60 amps between the wire and the alternator's B terminal. Reconnect the negative battery cable. Start the engine and run it to charge the battery until the charging rate is less than 5 amps. (If you have a fully charged battery available, it will save time to install it in place of the present one.) Pull the R-L connector out just slightly, so you can get the probe of a voltmeter in to read the voltage while the connection is maintained. Run the engine at 2,500 rpm and measure the voltage at the L terminal prong. If the voltage is 14.2-15.2 volts DC, the alternator is okay. If it is over 15.2 volts DC, there is a problem in the alternator; proceed with the next step.
  2.  
  3. Turn the ignition switch OFF . Disconnect the L-R connector at the alternator. Connect a voltmeter between the female R terminal (coming from the wiring harness) and the alternator housing or other ground. Turn the ignition switch ON and measure the voltage at the connector. If the voltage is less than battery voltage, repair the wiring harness. If the voltage is equal to battery voltage, proceed with the next step.
  4.  
  5. Turn the ignition switch OFF , then disconnect the negative battery cable and the wire from the alternator's B terminal. Connect an ohmmeter and measure the resistance between the L and F terminals on the alternator. If resistance is 3-6 ohms, the problem lies in the voltage regulator. If resistance is outside that range, the problem is in the rotor coil or brush(es).
  6.  

REMOVAL & INSTALLATION



See Figures 12, 13, 14, 15 and 16

  1. Disconnect the battery ground cable at the negative (-) terminal.
  2.  
  3. Remove the air cleaner as required. Remove the nut, and disconnect the alternator B terminal. Unplug the connector from the rear of the alternator.
  4.  



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Fig. Fig. 12: Remove the nut, and disconnect the alternator B terminal



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Fig. Fig. 13: Remove the bolt which secures the alternator to the adjusting link



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Fig. Fig. 14: Loosen the alternator pivot bolt, and relax the drive belt tension, before removing the drive belt(s)

  1. Remove the alternator adjusting link bolt(s). Do not remove the adjusting link. Remove the alternator drive belt. On the 626 diesel, this first requires loosening the air conditioner idler pulley, then removing the two alternator belts and the single air conditioning drive belt.
  2.  
  3. Remove the alternator securing nuts and bolts. Pull the drive belt(s) off the pulley and remove the alternator.
  4.  

To install:
  1. Position the alternator onto its mounting and install the attaching hardware.
  2.  
  3. Install the drive belt(s).
  4.  



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Fig. Fig. 15: Remove the alternator drive belt(s) and then the alternator



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Fig. Fig. 16: On 1979-82 RX-7s, alternator mounting clearance is adjusted with shims

  1. Plug the connector into the rear of the alternator. Clean the B wire terminal and install the wire with the nut.
  2.  
  3. Install the air cleaner, if removed, and connect the negative battery cable.
  4.  
  5. Adjust the drive belt tension as described in General Information & Maintenance .
  6.  

On 1979-82 RX-7s, when installing the alternator, check the clearance between the alternator and bracket. If the clearance is greater than 0.006 in. (0.15mm), reduce it with shims.

 
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