See Figures 1 and 2
The alternator charging system consists of the alternator, voltage regulator, warning light, battery, and fusible link wire.
A failure of any component of the charging system can cause the entire system to stop functioning. Because of this, the charging system can be very difficult to troubleshoot when problems occur.
When the ignition key is turned on, current flows from the battery, through the charging system indicator light on the instrument panel, to the voltage regulator, and to the alternator. Since the alternator is not producing any current, the alternator warning light comes on. When the engine is started, the alternator begins to produce current and turns the alternator light off. As the alternator turns and produces current, the current is divided into two areas: some goes to the battery to charge the battery and power the electrical components of the vehicle, while some is returned to the alternator, enabling it to increase its output. In this situation, the alternator is receiving current from the battery and from itself. A voltage regulator is wired into the current supply to the alternator to prevent it from receiving too much current, which would cause it to put out too much current. Conversely, if the voltage regulator does not allow the alternator to receive enough current, the battery will not be fully charged and will eventually go dead.
The battery is connected to the alternator at all times, whether the ignition key is turned on or not. If the battery were shorted to ground, the alternator would also be shorted. This would damage the alternator. To prevent this, a fusible link is installed in the wiring between the battery and the alternator. If the battery is shorted, the fusible link is melted, protecting the alternator.
Several precautions must be observed with alternator equipped vehicles to avoid damaging the unit. They are as follows:
- If the battery is removed for any reason, make sure that 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 it as follows: positive to positive, and negative (booster battery) to a good ground on the engine of the car being started.
- Never use a fast charger as a booster to start cars with alternating current (AC) circuits.
- When servicing the battery with a fast charger, always disconnect the car's battery cables.
- Never attempt to polarize an alternator.
- Avoid long soldering times when replacing diodes or transistors. Prolonged heat is damaging to alternators.
- Do not use test lamps of more than 12 volts (V) for checking diode continuity.
- Do not short across or ground any of the terminals on the alternator.
- 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 that all connections within the circuit are clean and tight.
- Disconnect the battery terminals when performing any service on the electrical system. This will eliminate the possibility of accidental reversal of polarity.
- Disconnect the battery ground cable if arc welding is to be done on any part of the car.
TESTING THE CHARGING SYSTEM
See Figures 3, 4, 5 and 6
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, causing the dashboard warning light to come on or the battery to "die''. 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:
In order for the current indicator to give a valid reading, the car must be equipped with battery cables which are of the same gauge size and quality as original equipment battery cables.
- Turn off all electrical components on the car. Make sure the doors of the car are closed. If the car is equipped with a clock, disconnect the clock by removing the lead wire from the rear of the clock. Disconnect the positive battery cable from the battery and connect the ground wire on a test light to the disconnected positive battery cable. Touch the probe end of the test light to the positive battery post. The test light should not light. (If the test light does light, there is a short circuit in the car's wiring. Pull the fuses one at a time, and check each circuit for a short. After locating the cause of the short, service wiring harnesses or components as required.)
- Disconnect the voltage regulator wiring harness connector at the voltage regulator. Turn on the ignition key. Connect the wire on a test light to a good ground (engine bolt). Touch the probe end of a test light to the ignition wire connector in the voltage regulator wiring harness connector. This wire corresponds to the I terminal on the regulator. If the test light goes on, the charging system warning light circuit is complete. If the test light does not come on and the warning light on the instrument panel is on, either the resistor wire, which is parallel with the warning light, or the wiring to the voltage regulator, is defective. If the test light does not come on and the warning light is not on, either the bulb is defective or the power supply wire form the battery through the ignition switch to the bulb has an open circuit. Reconnect the wiring harness to the regulator.
- Examine the fusible link in the wiring harness from the starter relay to the alternator. If the insulation on this wire is cracked or split, the fusible link may be melted. Connect a test light to the fusible link by attaching the ground wire on the test light to an engine bolt and touching the probe end of the light to the bottom of the fusible link where it splices into the alternator output wire. If the bulb in the test light does not light, the fusible link is melted.
- Start the engine and place a current indicator on the positive battery cable. Turn off all electrical accessories and make sure the doors are closed. If the charging system is working properly, the gauge will show a draw of less than 5 amps. If the system is not working properly, the gauge will show a draw of more than 5 amps. A charge moves the needle toward the battery, a draw moves the needle away from the battery. Turn the engine off.
- Disconnect the wiring harness connector from the voltage regulator. If the voltage regulator is an external type (separate from the alternator), connect a male spade terminal (solderless connector) to each end of a jumper wire. Insert one end of the wire into the wiring harness connector which corresponds to the A terminal on the regulator. Insert the other end of the wire into the wiring harness connector which corresponds to the F terminal on the regulator. (If the voltage regulator is integral with the alternator housing, the three-wire connector will not have an F terminal. In this case, connect a male spade terminal to one end of a jumper wire, and insert it into the wiring harness connector which corresponds to the A terminal on the regulator. Clip or hold the other end of the jumper wire to the regulator F terminal screw.) Position the connector with the jumper wire installed so that it cannot contact any metal surface under the hood. Position a current indicator gauge on the positive battery cable. Have an assistant start the engine and observe the reading on the current indicator. Have your assistant slowly raise the speed of the engine to about 2,000 rpm or until the current indicator needle stops moving, whichever comes first. Do not run the engine for more than a short period of time in this condition. If the wiring harness connector or jumper wire becomes excessively hot during this test, turn off the engine and check for a grounded wire in the regulator wiring harness. If the current indicator shows a charge of about three amps less than the output of the alternator, the alternator is working properly. If the previous tests showed a draw, the voltage regulator is defective. If the gauge does not show the proper charging rate, the alternator is defective.
- Disconnect the jumper wire and replace any faulty component.
REMOVAL & INSTALLATION
See Figures 7 through 13
- Disconnect the negative battery cable from the battery.
- Disconnect the wires from the alternator.
- Loosen the alternator mounting bolts and remove the drive belt(s).
Some 1981 and later cars are equipped with a ribbed, serpentine drive belt and automatic tensioner, which require the use of a prybar to remove the tension from the tensioner arm. Loosen the idler pulley pivot and adjuster bolts before using the tool. See General Information & Maintenance for further information on belt removal.
- Remove the alternator mounting bolts and spacer (if equipped), and remove the alternator.
- Position the alternator on its brackets and install the attaching bolts and spacer (if so equipped).
- Connect the wires to the alternator.
- Position the drive belt(s) on the alternator pulley, and adjust belt tension as outlined in General Information & Maintenance .
- Connect the negative battery cable.