Perkins 1103 / 1104 — Alternator - Test
Testing & diagnosis
For the Perkins 1103 / 1104, from the Perkins service manual.
Applies to: Perkins 1103, Perkins 1104, Perkins 1104 (1103 also covered) engine
Procedure
- Warning lamp does not illuminate: check the light bulb and replace if broken.
- Check battery voltage with the ignition switch OFF.
- Check voltage between terminal A and ground; it should equal battery voltage.
- Turn ignition switch ON and check voltage between terminal B and ground; if more than 2 volts the alternator needs replacement.
- Warning light on while running: run the engine at fast idle and measure voltage at terminals A and B.
- Voltages should be 13 to 15 volts (12 volt system) or 26 to 30 volts (24 volt system); if not, replace the alternator.
- Increase to high idle with an electrical load ON and repeat voltage measurement; replace the alternator if voltages do not match.
Tools required
- Multimeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 13 to 15 volts for a 12 volt system.
- 26 to 30 volts for a 24 volt system.
- If terminal B voltage is more than 2 volts the alternator needs to be replaced.
Full service-parts list: Perkins 1103 →, Perkins 1104 →
Source: Perkins 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.