GM Storm/Spectrum 1985-1993 Repair Guide

Alternator

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ALTERNATOR PRECAUTIONS



Several precautions must be observed with alternator equipped vehicles to avoid damage to the unit.



If the battery is removed for any reason, make sure it is reconnected with the correct polarity. Reversing the battery connections may result in damage to the one-way rectifiers.
 
When utilizing a booster battery as a starting aid, always connect the positive to positive terminals and the negative terminal from the booster battery to a good engine ground on the vehicle being started.
 
Never use a fast charger as a booster to start vehicles.
 
Disconnect the battery cables when charging the battery with a fast charger.
 
Never attempt to polarize the alternator.
 
Do not use test lights of more than 12 volts when checking diode continuity.
 
Do not short across or ground any of the alternator terminals.
 
The polarity of the battery, alternator and regulator must be matched and considered before making any electrical connections within the system.
 
Never separate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.
 
Disconnect the battery ground terminal when performing any service on electrical components.
 
Disconnect the battery if arc welding is to be done on the vehicle.
 

DIAGNOSIS & TESTING



Whenever troubleshooting the charging system, always check for obvious problems before proceeding, such as loose belts, bad electrical or battery connections, blown fuses, broken wires, etc.. The battery must be in good condition and in the proper state of charge. When performing tests, make sure the ignition is OFF before connecting or disconnecting test equipment.

Spectrum

See Figures 1, 2 and 3

The following procedure requires the use of a special alternator/charging system tester which should be available from your dealer. An equivalent tester may be available from aftermarket sources, but be sure the tester is compatible with your vehicle before attempting to use it. When using an equivalent aftermarket tester, follow the tool manufacturer's instructions for installation and diagnosis. Incorrect diagnosis could lead to unnecessary repairs.

  1. Turn the ignition OFF .
  2.  
  3. Set the checker switch to 12V.
  4.  
  5. Install the checker harness connector (black, red, white/red wires in the 4-pole connector) to the checker.
  6.  
  7. Install the extension harness (white/red wire, single female connector) to the checker harness.
  8.  
  9. Install the other end of the extension harness to the alternator L-lead wire (white/red).
  10.  
  11. Connect the black alligator clip to the negative battery terminal, then connect the red alligator clip to the positive battery terminal.
  12.  
  13. Check the condition of the alternator, refer to appropriate figures as a guide.
  14.  



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Fig. Fig. 1: Connecting the charging system tester



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Fig. Fig. 2: Checking the alternator condition



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Fig. Fig. 3: Diagnosing tester results

Storm
1990-1992 VEHICLES

See Figures 4 and 5

The following procedure requires the use of an Digital Volt/Ohm Meter (DVOM) or multimeter and a battery tester (carbon pile load tester). The alternator in the Storm uses 2 terminals; the battery positive and the L terminal (to the charge indicator). There are other, optional terminals, which may exist on some models. If present, each terminal (P, I and S) is connected to a specific position; the stator (P) and internal positive field (I) or serves a specific function; is available for connecting an external voltage source (S).

The possible problems which may exist in the charging system are; a faulty charge indicator circuit, a battery undercharge condition (indicated by slow cranking or by the hydrometer eye) or a battery overcharge condition (indicated by electrolyte spewing from the battery vents).

  1. Before proceeding look for obvious causes of charging system problems. Check all system wiring for improper or loose connections. Inspect belt tension and condition. Inspect the battery for proper charge. Refer to General Information & Maintenance of this repair guide for appropriate procedures.
  2.  
  3. If the vehicle is equipped with a battery charge light in the instrument cluster, proceed as follows:
    1. Turn the ignition system to the RUN position, but do not start the engine. If the charging lamp does not illuminate, unplug the alternator connector, then attach a fused jumper between terminal L and a good chassis ground. If the lamp lights with the jumper in position, replace the alternator. If the lamp does not illuminate, locate and repair the open between the alternator and ignition switch.
    2.  
    3. With the charging lamp illuminated, start the engine and run at a moderate speed; the lamp should extinguish. If not, carefully unplug the alternator connector for a few moments. A faulty alternator is indicated, if the lamp extinguishes only when the wiring harness is disconnected. If the lamp remains on, check for a grounded terminal wire in the harness.
    4.  

  4.  
  5. With the ignition OFF , disconnect the wiring harness connector from the alternator.
  6.  
  7. Connect a DVOM between the alternator connector terminal L and a good chassis ground. The reading should be 10 volts or more; if not check and repair the open between the terminal and the battery.
  8.  
  9. Install the wiring harness connector to the alternator.
  10.  
  11. Connect the DVOM across the battery terminals, then start and run the engine. Make sure ALL accessories turned OFF and, if equipped with power steering, the wheels are pointed to the straight-ahead position. The reading should be less than 16 volts; if not, replace the alternator.
  12.  
  13. Remove the DVOM from the battery terminals and switch it to the amperage setting, then connect it to the alternator output terminal and the battery negative terminal.
  14.  
  15. Turn on all accessories and load the battery using a carbon pile tester; refer to the battery sticker for proper load requirements.
  16.  
  17. Maintain voltage at 13 volts or higher and check the alternator amperage using the DVOM. If amperage is between 60-90 amps the alternator is good. If a problem is still suspected and the alternator tests properly, refer to General Information & Maintenance of this repair guide for battery checking procedures.
  18.  



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Fig. Fig. 4: Charging system schematic - Storm 1990-1992 vehicles



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Fig. Fig. 5: Alternator testing - Storm 1990-1992 vehicles

1993 VEHICLES

See Figure 6

The following procedure requires the use of an Digital Volt/Ohm Meter (DVOM) and an ammeter. The alternator in the Storm vehicles uses 2 terminals; the battery positive and the L terminal (to the charge indicator). There are other, optional terminals, which may exist on some models. If present, each terminal (P, I and S) is connected to a specific position; the stator (P) and internal positive field (I) or serves a specific function; is available for connecting an external voltage source (S).

  1. Before proceeding look for obvious causes of charging system problems. Check all system wiring for improper or loose connections. Inspect belt tension and condition. Inspect the battery for proper charge. Refer to General Information & Maintenance of this repair guide for appropriate procedures.
  2.  
  3. With the engine and all accessories turned OFF , connect a DVOM across the battery terminals.
  4.  
  5. Start the engine and run it at a moderate speed, then check battery voltage.
  6.  

When testing voltage, give consideration to the affect temperature will have on the regulator. As the temperature of the regulator case (mounted in the alternator) increases, voltage output will decrease.

  1. The standard setting for the regulator is 14.2-14.8 volts at 77°F(-25°C). Under normal operating conditions, the reading should be at least 13.5 volts.
  2.  
  3. If the previous tests do not reveal the trouble, turn the engine OFF and disconnect the negative battery cable.
  4.  
  5. Remove the rubber protector, nut and the alternator positive wire from the alternator positive terminal.
  6.  
  7. Install an ammeter between the alternator and the disconnected wire. Connect the ammeter negative lead (black wire) to the wire and the red lead (positive wire) to the alternator battery terminal.
  8.  
  9. Install a DVOM between the alternator positive battery terminal and a good chassis ground.
  10.  
  11. Start the engine and run it at 2000 rpm, then turn all accessories and the headlight high-beams ON. Make sure the heating and ventilating blower motor is the maximum position.
  12.  
  13. Adjust the engine speed, as necessary, to obtain the maximum current output. With the voltage between 13.5-16.0 volts, the alternator output should be 45-65 amps. If not, the alternator is faulty.
  14.  



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Fig. Fig. 6: Regulator voltage vs. temperature graph

REMOVAL & INSTALLATION



Spectrum
  1. Disconnect the negative battery terminal from the battery.
  2.  

Failure to disconnect the negative cable may result in injury from the positive battery lead at the alternator and may short the alternator and regulator during the removal process.

  1. Disconnect and label the terminal plug and the battery lead from the rear of the alternator.
  2.  
  3. Loosen the mounting bolts. Push the alternator inwards and slip the drive belt off the pulley.
  4.  
  5. Remove the mounting bolts and remove the alternator.
  6.  

To install:
  1. Place the alternator in its brackets and install the mounting bolts. Do not tighten them yet.
  2.  
  3. Slip the belt back over the pulley. Pull outwards on the unit and adjust the belt tension. Tighten the mounting and adjusting bolts.
  4.  
  5. Install the electrical leads and the negative battery cable.
  6.  

Storm
EXCEPT VIN 8 ENGINE

See Figure 7

  1. Disconnect the battery negative cable and remove the belt adjusting bolt from the alternator.
  2.  
  3. Raise and support the vehicle safely, then remove the right undercover (splash shield).
  4.  
  5. Loosen the lower retaining bolt. Remove the alternator belt, then tag and disconnect electrical leads from the alternator.
  6.  
  7. Remove alternator mounting bracket-to-engine block attaching bolts, then remove the alternator and bracket from the vehicle. If necessary, disconnect the alternator from the bracket by removing the bolt(s).
  8.  
  9. Installation is reverse of the above procedure. When reinstalling, remember to leave the bolts finger tight so that the belt may be adjusted. The bracket-to-block bolts should be tightened to 24 ft. lbs. (33 Nm).
  10.  
  11. Make sure that all electrical connectors are properly seated and secure in their mounts.
  12.  



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Fig. Fig. 7: Loosening the alternator upper adjusting belt

VIN 8 ENGINE

See Figure 8

  1. Disconnect the negative battery cable.
  2.  
  3. For 1993 vehicles, unplug the oxygen sensor electrical connector.
  4.  
  5. Remove the five retaining bolts, then reposition the exhaust manifold heat shield out of the way.
  6.  
  7. Rotate the serpentine drive belt tensioner to loosen the belt, then remove the belt from the tensioner and set aside.
  8.  
  9. Remove the 2 nuts and the wiring harness retainer from the power steering pump.
  10.  
  11. Remove the electrical connector and the 3 bolts from the power steering pump, then reposition the assembly out of the way. Be careful not to kink or damage the pump hoses.
  12.  
  13. Tag and disconnect the electrical connections from the alternator.
  14.  
  15. Raise and support the vehicle safely. Remove the seven screws and the right splash shield, then remove the lower bolt and nut from the alternator.
  16.  
  17. Remove the supports and carefully lower the vehicle, then remove the upper alternator bolt and the 2 upper mounting bracket bolts. Remove the alternator and mounting bracket from the vehicle.
  18.  

To install:
  1. Position the alternator in the vehicle and loosely install a fastener to retain it while the vehicle is raised. Raise and support the vehicle safely.
  2.  
  3. Install the lower bolt and nut to the alternator, but do not fully tighten at this time. Remove the supports and carefully lower the vehicle.
  4.  
  5. Secure the alternator mounting bracket to the engine by tightening the retaining bolts to 24 ft. lbs. (33 Nm).
  6.  
  7. Install the upper bolt to the alternator and tighten to 24 ft. lbs. (33 Nm).
  8.  
  9. Install the electrical connections to the alternator. If equipped with a retaining nut (as opposed to a snap-connector), tighten the nut to 11 ft. lbs. (15 Nm).
  10.  
  11. Position the power steering pump assembly, install the electrical connector and tighten the 3 assembly retaining bolts to 22 ft. lbs. (30 Nm).
  12.  
  13. Install the wiring harness retainer to the pump assembly, then secure by tightening the 2 nuts to 89 inch lbs. (10 Nm).
  14.  
  15. Rotate the belt tensioner, then install the serpentine drive belt, making sure the belt is properly aligned on all pulleys.
  16.  
  17. Position the heat shield to the exhaust manifold and tighten the retaining bolts to 11 ft. lbs. (15 Nm). For 1993 vehicles, install the wiring harness to the oxygen sensor.
  18.  
  19. Raise and support the vehicle safely, then install the splash shield using the 7 retaining screws. Remove the supports and carefully lower the vehicle.
  20.  
  21. Connect the negative battery cable.
  22.  



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Fig. Fig. 8: Alternator mounting - Storm VIN 8 engine

 
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