Starter Cranks Slowly

Verify battery condition. Battery voltage should be 12 volts or more. Load test battery at approximately one-half cold cranking amperage rating. See load tester manufacturer's instructions. If battery voltage is less than 12 volts or loaded battery voltage is less than 9.6 volts, service battery or charging system as necessary. If battery is okay, go to next step.
Perform VOLTAGE DROP TEST under ON-VEHICLE TESTING. If voltage drop is okay, go to next step. If voltage drop is excessive, repair cable connections or replace cable as necessary. Restore electrical connections and check system operation.
Perform STARTER NO-LOAD TEST under ON-VEHICLE TESTING. If current draw is within specification, check engine for mechanical concerns. If current draw is excessive, repair or replace starter motor. See STARTER MOTOR under REMOVAL & INSTALLATION. Restore electrical connections and check system operation.