In case the starting circuit has a problem, it is important to not jump to conclusions that the problem is with the starter. Start by inspecting a number of key components and connections. First, ensure that
Battery Cable clamps are securely and cleanly attached to battery terminals. Second, evaluate the state of battery cables and replace any ruined ones with new parts as necessary. Thirdly, examine battery's condition by conducting tests; if it fails these tests in any way replace it with a new one. Moreover, check on wiring and connections for starter motor as well as confirm for tightness of starter motor mounting bolts. Inside the fuse box check related fuses and rectify blow fuses after identifying which blew up so as to correct underlying circuit malfunction. Ascertain whether ignition switch circuit is functioning properly while inspecting the starter relay too. Also confirm that Park/Neutral position switch (for automatic transmissions) or clutch start switch (for manual transmissions) is functioning correctly since it should provide battery voltage to the starter solenoid. In addition if when turning ignition switch to start position starter does not activate then check at the starter solenoid for battery voltage so as certify that it receives right voltage from ignition switch. With an assistant turn ignition switch to start while using a 12-volt test light or voltmeter connected to starter solenoid terminal; test light should glow brightly or voltmeter should read battery voltage. If there is lack of voltage at the starter solenoid consult wiring diagrams and troubleshoot fuses, switches, and starting system relay in series with them. Suppose there is presence of voltage but no movement from the starter motor remove such a motor from its engine and conduct bench test on it instead . Slow turnover may be due to various factors like low battery cranking speed rating, dirty cables or terminals on batteries or extreme cold conditions whereby heating batteries or engine block prior testing would help . Finally if you have voltage but no activation from the starter, pull the starter motor assembly out and test it on bench; pay attention to proper solenoid operation, starter motor as well as other related elements with special focus on seizure of engine possibility by trying to turn crankshaft pulley first.