To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.
- Never reverse battery connections. Always check the battery polarity visually. This should be done before any connections are made to be sure that all of the connections correspond to the battery ground polarity of the truck.
- Booster batteries for starting must be connected properly. Make sure that the positive cable of the booster battery is connected to the positive terminal of the battery that is getting the boost. The same applies to the negative cables.
- Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction for which they were designed. This burns out the diodes.
- Never use a fast charger as a booster for starting the vehicle.
- Never disconnect the voltage regulator while the engine is running.
- Do not ground the alternator output terminal.
- Do not operate the alternator on an open circuit with the field energized.
- Do not attempt to polarize an alternator.
CHARGING SYSTEM TROUBLESHOOTING
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 become dead. 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:
- The battery is known to be good and fully charged.
- The alternator belt is in good condition and adjusted to the proper tension.
- All connections in the system are clean and tight.
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 light does light, there is a short or open circuit on the car.
- 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 into the voltage regulator wiring 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. Connect the wiring harness to the regulator.
- Examine the fuse link wire at the wiring harness from the starter relay to the alternator. If the insulation on the wire is cracked or split, the fuse link may be melted. Connect a test light to the fuse 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 fuse link wire where it splices into the alternator output wire. If the bulb in the test light does not light, the fuse 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 from the voltage regulator at the regulator at the regulator connector. Connect a male (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. 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. 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 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.
REMOVAL & INSTALLATION
See Figures 1, 2, 3, 4, 5, 6, 7, 8 and 9
- Open the hood and disconnect the battery ground cable.
- Remove the adjusting arm bolt and loosen the pivot bolt.
- Remove the drive belt from the alternator pulley.
- Label all the leads to the alternator so that they can be reinstalled correctly and remove the leads from the alternator.
- Remove the alternator pivot bolt and remove the alternator from the truck.
- To install, reverse the above service procedure.