Detroit Diesel — Exciter Armature Test Procedure
Testing & diagnosis
From a Detroit Diesel service manual — check it applies to your exact model before use.
Procedure
- Disassemble the alternator.
- Disconnect the armature leads from the RRA AC terminals.
- With ohmmeter on R x 1 scale, check resistance across exciter armature leads.
- Megohmmeter test: apply 500 V DC to either armature lead and armature frame; replace if less than ~500 kOhms.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- No continuity indicates an open armature winding
- Good insulation reading approximately 500 kOhms (1/2 megohm) and higher
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.