Starting/Charging Systems: Generator: Inspection: Rotor

Inspect the slip rings for contamination or any roughness on the sliding surface. Repair the slip ring surface using a lathe or sand paper.

Measure the slip ring outer diameter. If the slip ring is worn, replace the rotor assembly.

Slip ring outer diameter: 

Standard 

22.7 mm (0.894 in) 

Limit 

22.1 mm (0.870 in) 

Check the resistance between slip rings using circuit tester.

If the resistance is not within the specified range, replace the rotor assembly.

Specified resistance: 

Approx. 1.8 - 2.2 Ω 

Fig 1: Checking Resistance Between Slip Rings Using Circuit Tester

Courtesy of SUBARU OF AMERICA, INC.

Check the continuity between slip ring and rotor core or shaft. If resistance is 1 Ω or less, the rotor coil is grounded, and so replace the rotor assembly.

Fig 2: Checking Continuity Between Slip Ring And Rotor Core Or Shaft

Courtesy of SUBARU OF AMERICA, INC.

Check the rear ball bearing. Replace if it is noisy or if the rotor does not turn smoothly.