Rectifier and Stator Grounded Tests

This test is performed with an ohmmeter, Rotunda Dwell-Tach-Volt-Ohmmeter or equivalent. Place the Multiply-By setting at 1 and calibrate the ohmmeter.

NOTE: Text values shown in brackets [ ] are referenced to Rotunda Dwell-Tach-Volt-Ohmmeter 059-00010, and may be different if another tester is used.

CAUTION: Digital meters cannot be used to perform these rectifier tests.









1. Contact one ohmmeter probe of one of the alternator B+ blade terminals and the other probe to the STA blade terminal. 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 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.

Alternator W/Integral Regulator Rectifier Short Or Grounded & Stator Grounded Test:

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 damaged 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.