Inspect commutator for dirt or signs of burning. If dirt or burning is present, sand lightly with No. 300-400 sand paper or lathe as necessary to clean surface.
Using a dial indicator, check commutator for runout. Standard runout is .0019" (.05 mm). Maximum runout is .015" (.4 mm). If runout exceeds maximum limit, replace commutator.
Using a micrometer, measure diameter of brush end of commutator. On Samurai, standard measurement is 1.26" (32 mm). Minimum measurement is 1.22" (31 mm). On Sidekick and Swift GT (A/T), standard measurement is 1.16" (29 mm). Minimum measurement is 1.13" (29 mm). On all Swift models except GT (A/T), minimum measurement is 1.06" (27 mm). If measurement is less than minimum, replace commutator.
Measure depth of grooves between commutator segments and insulators. See Fig 1. On Samurai, standard depth is .015-.023" (.4-.6 mm). Minimum depth is .0078" (.2 mm). On Sidekick and Swift GT (A/T), standard depth is .020-.031" (.5-.8 mm). Minimum depth is .0078" (.2 mm). On all Swift models except GT (A/T), minimum depth is .0078" (.2 mm). If measurement is less than minimum depth, replace commutator.

Fig 1: Measuring Depth of Commutator Segment Grooves

Courtesy of SUZUKI OF AMERICA CORP.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Repair and Diagnosis: Electrical: Starter: Overhaul: Inspection: Commutator