Rectifier Shorted Or Grounded & Stator Grounded Test
- Using an ohmmeter set in "x1" range, connect one probe to alternator rectifier "B+" terminal and other probe to STA terminal. See Fig 1. Reverse terminal probes and repeat test.
- Ohmmeter should read about 6.5 ohms resistance in one direction and infinity when probes are reversed. Same reading in both directions indicates bad positive diode or shorted radio suppression capacitor.
- Perform same test using STA terminal and rear alternator housing. Same reading in both directions indicates bad negative diode, grounded stator winding, grounded stator terminal or shorted radio suppression capacitor.
- If in preceding tests, no needle movement is indicated in one direction, or high resistance (considerably more than 6.5 ohms) is indicated in other direction, open circuit exists in rectifier assembly.
Courtesy of FORD MOTOR CO.