The first test which should be performed is a visual inspection of all charging system components.
- Inspect the condition of the battery cable terminals, battery posts, connections at the engine block, starter motor solenoid and relay. All connections should be clean and tight. All wire casings should be intact. If corrosion is evident, it can be easily cleaned by using a paste made from a mixture of baking soda and water.
- Inspect all fuses in the fuse block for tightness in their receptacles. Replace any loose or blown fuses.
- Check the electrolyte level in the battery. This can be done using a hydrometer. Add water to the battery and recharge if necessary.
- Inspect alternator mounting bolts for tightness. Bolts should be torqued to 23-30 ft. lbs. (31-40 Nm).
- Inspect the alternator drive belt condition and tension. Adjust and/or replace as necessary. Drive belt should be torqued to 140-160 ft. lbs.. if used, and 180-200 ft. lbs.. if new.
- Inspect the connection at the alternator BAT terminal (usually located on the back side of the alternator). This is the alternator output to the battery. Assure that it rnator). This is the alternator output to the battery. Assure that it is clean and tight.
After the visual inspection is complete, perform the following alternator and battery tests until the problem is found.
- Turn off all electrical components on the vehicle. Make sure the doors of the car are closed. If the vehicle 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 or open circuit on the vehicle.
- 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 from 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 in 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 .
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.
- Disconnect the wiring harness from the voltage regulator at the regulator. 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. 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 2000 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.
Removal & Installation
Once the determination is made that the alternator is at fault, off vehicle testing can be used to determine the defective component inside the alternator.
See Figures 1 through 11
- Disconnect the negative battery cable.
- Remove the drive belt.
- If necessary, remove any splash shielding for easier access to the alternator.
- Tag and disengage the alternator wiring.
It may be necessary to remove the alternator and mounting bracket from the vehicle as an assembly.
- If equipped, remove the front alternator assembly mounting plate.
- Unfasten the alternator mounting and pivot bolts and remove the alternator.
- If installing the original alternator assembly, push out the pivot bushing as illustrated.
- Mount the alternator to the brackets with the nuts and bolts. Tighten the two mounting bolts and nuts to 40 ft. lbs. (54 Nm).
- If the alternator and mounting bracket were removed as an assembly, install the assembly into the vehicle.
- If removed, install the front mounting plate.
- Engage the alternator electrical connections.
- If removed, install the splash shield.
- Install the drive belt and attach the negative battery cable.