Mazda Trucks 1987-1993 Repair Guide

Alternator

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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:

  1. The battery is known to be good and fully charged.
  2.  
  3. The alternator belt is in good condition and adjusted to the proper tension.
  4.  
  5. All connections in the system are clean and tight.
  6.  

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
  1. Ensure that the ignition switch is turned OFF .
  2.  
  3. Connect a tachometer to the engine by following the manufacturer's instructions.
  4.  
  5. Using a Digital Volt Ohmmeter (DVOM) measure the voltage across the positive (+) and negative (-) battery terminals. Note the voltage reading for future reference.
  6.  

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.

  1. Start the engine and have an assistant run it at 1500 rpm.
  2.  
  3. Read the voltage across the battery terminals again. The voltage should now be between 14.1-14.7 volts.
    1. If the voltage increase is less than 2.5 volts over the base voltage measured in Step 3, perform the Battery Load test.
    2.  
    3. If there was no voltage increase, or the voltage increase was greater than 2.5 volts, perform the Alternator Load and No-Load tests.
    4.  

  4.  

Battery Load Test

  1. With the engine running, turn the air conditioner ON (if equipped) or the blower motor on high speed and the headlights on high beam.
  2.  
  3. Have your assistant increase the engine speed to approximately 2000 rpm.
  4.  
  5. Read the voltage across the battery terminals again.
    1. 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.
    2.  
    3. If the voltage does not increase as indicated, perform the Alternator Load and No-Load tests.
    4.  

  6.  

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 car's battery. Use a tester designed for charging system analysis, such an Alternator, Regulator, Battery and Starter Motor Tester unit.

  1. Switch the tester to the ammeter setting.
  2.  
  3. Attach the positive (+) and negative (-) leads of the tester to the battery terminals.
  4.  
  5. Connect the current probe to the B+ terminal on the alternator.
  6.  
  7. 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 alternator's output rating; if so, continue with the Alternator No-Load test. If the output is not within ten percent of the alternator's output rating, there is a problem in the charging system. Have the system further tested by a Ford qualified automotive technician.
  8.  

Alternator No-Load Test

  1. Using the same tester as in the Alternator Load Test, switch the tester to the voltmeter function.
  2.  
  3. Connect the voltmeter positive (+) lead to the alternator B+ terminal and the negative (-) lead to a good engine ground.
  4.  
  5. Turn all of the electrical accessories off and shut the doors.
  6.  
  7. 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.
  8.  

REMOVAL & INSTALLATION



2.2L Engine
  1. Disconnect the negative (ground) cable. On some models, it may be necessary to remove the battery.
  2.  
  3. Remove the nut holding the alternator wire to the terminal at the rear of the alternator.
  4.  
  5. Pull the multiple connector from the rear of the alternator.
  6.  
  7. Remove the alternator adjusting arm bolt. Swing the alternator in and disengage the fan belt.
  8.  
  9. Remove the alternator pivot bolt and remove the alternator from the truck.
  10.  
  11. Place the alternator in position and install the pivot bolt hand tight. Install the adjusting arm bolt. Place the drive belt in position and tension it properly. Secure the adjusting and pivot bolts. Be sure to adjust the drive belt tension and to connect the battery properly.
  12.  

2.6L Engine

1987-88
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring and label for easy installation.
  4.  
  5. Remove the adjusting strap mounting bolt.
  6.  
  7. Remove the drive belts.
  8.  
  9. Remove the support mounting bolt and nut.
  10.  
  11. Remove the alternator assembly.
  12.  
  13. Position the alternator assembly against the engine and install the support bolt.
  14.  
  15. Install the adjusting strap mounting bolt.
  16.  
  17. Install the alternator belts and adjust to specification.
  18.  
  19. Tighten all the support bolts and nuts.
  20.  
  21. Connect all alternator terminals.
  22.  
  23. Connect the negative battery cable.
  24.  

1989-93
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring and label for easy installation.
  4.  
  5. Remove the power steering pump pulley, if it interferes with alternator removal.
  6.  
  7. Remove the drive belts.
  8.  
  9. Remove the support mounting bolt and nut.
  10.  
  11. Remove the alternator assembly.
  12.  
  13. Position the alternator assembly against the engine and install the support bolt.
  14.  
  15. Install the adjusting strap mounting bolt.
  16.  
  17. Install the alternator belts and adjust to specification.
  18.  
  19. Install the power steering pump pulley.
  20.  
  21. Tighten all the support bolts and nuts.
  22.  
  23. Connect all alternator terminals.
  24.  
  25. Connect the negative battery cable.
  26.  

3.0L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring and label for easy installation.
  4.  
  5. Remove the mounting and adjusting bolts.
  6.  
  7. Remove the drive belts.
  8.  
  9. Remove the alternator assembly.
  10.  
  11. Position the alternator assembly against the engine and install the support bolt.
  12.  
  13. Install the adjusting strap mounting bolt.
  14.  
  15. Install the alternator belts and adjust to specification.
  16.  
  17. Tighten all the support bolts and nuts.
  18.  
  19. Connect all alternator terminals.
  20.  
  21. Connect the negative battery cable.
  22.  

4.0L Engine

  1. Disconnect the battery ground cable.
  2.  
  3. Disconnect the wire harness connector from the alternator. Remove the wiring connector bracket.
  4.  
  5. Remove the drive belt.
  6.  
  7. Remove the mounting bolts and the alternator.
  8.  
  9. Position the alternator and install the mounting bolts. Install the drive belt. Secure the wiring connector bracket to the alternator and connect the wiring harness. Connect the battery ground cable.
  10.  

 
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