Adjustments & Testing

ADJUSTMENTS

Belt Adjustments

For belt adjustment, see Integral Charging System - General Service, Adjustments.

TESTING

Bench Tests

If the general charging system diagnosis has isolated a problem to the integral alternator/regulator assembly, remove it from the vehicle for bench testing and service or replace. See the paragraphs on IAR assembly removal and disassembly in this section. In some cases, it may be possible to replace a defective regulator or brushes without removing the IAR assembly.
Rectifier Short or Grounded and Stator Grounded Test

These tests are performed with an ohmmeter (Tool 059- 00010 or equivalent). Put the "Multiply By" setting at 1 and calibrate the ohmmeter as directed. Test values shown in brackets () are referenced to Tool 059-00010 and may be different if another tester is used.

WARNING: DIGITAL METERS CANNOT BE USED TO PERFORM THESE RECTIFIER TESTS.

Figure 7:

1. Contact one ohmmeter probe to one of the alternator B+ blade terminals and the other probe to the STA blade terminal (Figure 7). Then, reverse the ohmmeter probes and repeat the test. Normally, there will be no needle movement in one direction, indicating the rectifier diodes are being checked in the reverse current direction and are not shorted. A low reading of about (6.5) ohms with the probes reversed indicates that rectifier positive diodes are being checked in the forward current direction. A low reading in both directions indicates a bad positive diode or shorted radio suppression capacitor. The radio suppression capacitor is built into the rectifier assembly and is not individually serviceable.

2. Perform the same test using the STA blade terminal and alternator rear housing. A reading in both directions indicates either a grounded stator winding, a bad negative diode, a grounded stator lead wire or a shorted radio suppression capacitor.

3. If there is no needle movement with the probes in one direction and no needle movement or high resistance (significantly over (6.5) ohms) in the opposite direction for Tests 1 and 2, a bad connection exists in the rectifier assembly.
Field Open or Shorted Circuit Test

This test is performed with an ohmmeter (Tool 059- 00010 or equivalent).

Put the "Multiply By" setting at 1 and calibrate the ohmmeter as directed. Text values shown in brackets () are referenced to Tool 059-00010 and may be different if another tester is used.

Figure 8:

1. Contact the regulator A blade terminal with one probe and the regulator F screw head with the other probe (Figure 8). Then, spin the alternator pulley. Reverse the ohmmeter probes and repeat the test. In one probe direction, the ohmmeter reading should be between 2.2 and 100 ohms and may fluctuate while the pulley is turning. In the other probe direction, the reading should fluctuate between 2.2 and about (9) ohms.

2. An infinite reading (no meter movement) in one direction and about (9) ohms in the other indicates an open brush lead, worn or struck brushes, a bad rotor or loose regulator to brush holder attaching screw.

3. An ohmmeter reading less than 2.2 ohms in both directions indicates a shorted rotor or bad regulator.
4. An ohmmeter reading significantly over (9) ohms in both directions indicates a defective regulator or loose F terminal screw.

5. Contact the alternator rear housing with one ohmmeter probe and touch the other probe first to the regulator A blade terminal and then to the regulator F screw head. An ohmmeter reading less than infinite at either point indicates a grounded brush lead, grounded rotor or bad regulator.
Rectifier Assembly Test

Remove the rectifier assembly from the alternator. Put the ohmmeter (Tool 059-00010 or equivalent) "Multiply By" setting at 1 and calibrate the meter as directed. Text values shown in brackets () are referenced to Tool 059-00010 and may be different if another tester is used.

WARNING: DIGITAL METERS CANNOT BE USED TO PERFORM THESE TESTS.

Figure 9:

1. To test the positive diodes, contact one probe to one of the rectifier assembly B+ blade terminals and contact each of the three stator terminals with the other probe (Figure 9). Reverse the probes and repeat the test. All diodes should show a low reading of about (7) ohms in one direction and an infinite reading (no needle movement) with the probes reversed. This reading may be checked against a good rectifier if one is available.

2. Perform the preceding tests for the negative diodes by contacting the rectifier assembly base plate and the three stator terminals.
3. If the meter readings are not as specified, replace the rectifier assembly.

Radio Suppression Capacitor Open or Short Test

NOTE: This is an open or short circuit test only and does not measure capacitance value. Actual capacitance value should be measured on a capacitance bridge at 1 kHz at a maximum voltage of 35O mV rms.

The radio noise suppression capacitor is built into the rectifier assembly and cannot be serviced by itself. To test the capacitor, put the ohmmeter (Tool 059-00010 or equivalent) "Multiply By" setting at 1000 and zero the meter. Text values shown in brackets () are referenced to Tool 059-00010 and may be different if another tester is used.

WARNING: DIGITAL METERS CANNOT BE USED TO PERFORM THIS CAPACITOR TEST. THE RECTIFIER ASSEMBLY MUST BE DRY.
1. Contact one probe to one of the rectifier assembly B+ blade terminals and contact the other probe to the rectifier assembly base plate. Reverse the probes and repeat the test. One position should give an infinite reading, indicating the reverse current direction through the diodes and the reverse position should give a reading of about (1000) ohms, indicating the forward current direction. The same reading in both directions indicates a defective rectifier assembly.

2. Contact the probes to the rectifier assembly B+ terminal and base plate in the forward current (1000) ohms reading direction. While observing the meter indicator needle, reverse the probes and again contact them to the rectifier assembly B+ terminal and base plate. The indicator needle should jump slightly (indicating that the ohmmeter batteries are charging the capacitor) and then return to its original position (infinite reading).

If the needle does not jump, the capacitor is open. Replace the rectifier assembly.

Stator Coil Grounded Test

These tests are made to determine if the stator coil is operating properly. Remove the stator from the alternator and disconnect it from the rectifier assembly (refer to DISASSEMBLY procedure). Put the ohmmeter "Multiply By" setting at 1000.

Figure 10:

1. Connect the ohmmeter probes to one of the stator leads and to the stator laminated core (Figure 10). Be sure that the probe makes a good electrical connection with the stator core. The meter should show an infinite reading (no needle movement).

2. If the meter does not indicate an infinite reading (needle moves), the stator winding is shorted to the core and the stator must be replaced.

3. Repeat the test for each of the stator leads (Figure 10). Do not touch the metal probes or stator leads with the hands. Such contact will result in an incorrect reading.
Stator Coil Open Test

This test determines if there is an open stator circuit. Disconnect the stator from the rectifier assembly. Put the ohmmeter "Multiply By" setting at 1.

WARNING: A SINGLE OPEN PHASE CONNECTION WILL NOT BE DISCOVERED BY THIS TEST ON ALTERNATORS HAVING A "DELTA" CONNECTED STATOR.

Figure 10:

1. Connect one ohmmeter probe to a stator phase lead (Figure 10) and touch the other probe to another stator lead. Check the meter reading.
2. Repeat this test with the other two stator lead combinations. If no meter movement occurs (infinite resistance) on a lead paired with either of the other phase leads, that phase is open and the stator must be replaced.

Rotor Open or Short Test

Remove the rotor from the alternator. Put the ohmmeter "Multiply By" setting at 1 and calibrate the meter as described.
1. Contact each ohmmeter probe to a rotor slip ring. The meter reading should be 2.0 to 3.9 ohms.

2. A higher reading indicates a damaged slip ring welded connection or a broken wire.

3. A lower reading indicates a shorted wire or slip ring. Replace the rotor if it is damaged and cannot be serviced.

4. Contact the ohmmeter probe to a slip ring and the other probe to the rotor shaft. The meter reading should be infinite (no needle movement).

5. A reading other than infinite indicates the rotor coil is shorted to the shaft. Replace the rotor if it is shorted and cannot be serviced.