How do I test the alternator stator for continuity?

Separate the stator and diode by unsoldering the connecting wires, then perform a continuity test between the lead wires with an ohmmeter. If there is no continuity, replace the stator.

What does the stator ground test show?

Test between a lead wire and the stator core. If continuity exists, replace the stator.

What precaution applies when unsoldering the alternator diode wires?

Use only as much heat as required to melt the solder — diodes will be damaged by excessive heat. Long nose pliers can be used as a heat sink.

What are the correct ohmmeter readings for the alternator diodes?

Positive probe on terminal plate (B) to diode terminal: continuity Yes; reversed: No. (−) Heat sink to diode terminal: No; reversed: Yes. Terminal plate (L) to diode terminal: Yes; reversed: No.

What should I do if the diode conduction test fails?

If the conduction test is N.G. (no good), replace the diode assembly.

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Nissan Micra Alternator Stator & Diode Check - Continuity Test Procedure

Alternator stator and diode continuity-check instructions with ohmmeter figures

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Service procedure for stator and diode continuity checks on an alternator using an ohmmeter, with test tables and figures.

AI caption February 2006 · Photo 373 of 412

This is page EL-27 of a factory service manual covering the charging system (alternator), specifically the Stator Check and Diode Check procedures. The stator check requires unsoldering the connecting wires to separate stator and diode, with a caution to use only as much heat as needed to melt solder because excessive heat damages diodes (long nose pliers are shown used as a heat sink). Two stator tests are described: a continuity test between lead wires (no continuity means replace stator) and a ground test between lead wire and stator core (continuity means replace stator). The diode check is a continuity test with an ohmmeter, tabulated for six probe combinations: terminal plate (B) to diode terminal should show continuity while the reverse should not; (−) heat sink to diode terminal should show no continuity while the reverse shows continuity; terminal plate (L) to diode terminal shows continuity while the reverse does not. A labeled diagram identifies the (−) heat sink, diode terminal, terminal plates B and L, sub diode, and (+) heat sink. A positive diode test illustration follows; if the conduction test is N.G., the diode assembly must be replaced. Illustration reference codes SEL054D, SEL070, SEL071, SEL903A, and SEL904A appear.

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Frequently asked questions

How do I test the alternator stator for continuity?: Separate the stator and diode by unsoldering the connecting wires, then perform a continuity test between the lead wires with an ohmmeter. If there is no continuity, replace the stator.
What does the stator ground test show?: Test between a lead wire and the stator core. If continuity exists, replace the stator.
What precaution applies when unsoldering the alternator diode wires?: Use only as much heat as required to melt the solder — diodes will be damaged by excessive heat. Long nose pliers can be used as a heat sink.
What are the correct ohmmeter readings for the alternator diodes?: Positive probe on terminal plate (B) to diode terminal: continuity Yes; reversed: No. (−) Heat sink to diode terminal: No; reversed: Yes. Terminal plate (L) to diode terminal: Yes; reversed: No.
What should I do if the diode conduction test fails?: If the conduction test is N.G. (no good), replace the diode assembly.