Operation of the starting system is basically similar on all models, although starter motor specifications may differ for each engine family.
The starting system includes the battery, starter motor, solenoid, ignition switch and, in some cases, a starter relay. An inhibitor switch (neutral safety) is included in the starting system circuit to prevent the vehicle from being started while in gear.
When the ignition key is turned to the START position, current flows and energizes the starter's solenoid coil. The energized coil becomes a magnet that pulls the plunger into the coil, and the plunger closes a set of contacts, which allow high current to reach the starter motor. The plunger also serves to push the starter pinion into the teeth on the flywheel/flexplate.
To prevent damage to the starter motor when the engine starts, the pinion gear incorporates an over-running (one-way) clutch which is splined to the starter armature shaft. The rotation of the running engine may speed the rotation of the pinion, but not the starter motor itself.
Some starting systems employ a starter relay in addition to the solenoid. This relay may be located under the dashboard, in the kick panel, or in the fuse/relay center under the hood. This relay is used to reduce the amount of current that the ignition switch must carry.
Always disconnect the negative battery cable before servicing the starter. Battery voltage is always present at the large B terminal on the solenoid. When removing the starter motor, be prepared to support its weight after the last bolt is removed, because the starter motor is a very heavy component.
NEVER operate the starter for more than 30 seconds at a time. Too much cranking will cause the starter motor to overheat, causing permanent damage. Allow the starter to cool for at least two minutes between starting attempts.
Any troubleshooting of the starting system should start with checks of the following components:
Ensure that the battery is in good condition and fully charged. Simply checking for voltage across the terminals will NOT indicate battery condition. A load test is required. This requires special equipment, but a local garage or parts store may be able to help. Check the battery and clean the connections as follows:
- If the battery cells have removable caps, check the water level. Add distilled water if low. Load test the battery and charge if necessary.
- Remove the cables and clean them with a wire brush. Reconnect the cables.
- Check for voltage across and battery posts and across the clamps to ensure that clamp connections are making good contact.
- On manual trans. models, disconnect the clutch position switch and connect a jumper across the harness connector to simulate depressing the clutch pedal.
- Connect the voltmeter leads to the battery positive (+) terminal and the starter solenoid battery cable stud. Turn the ignition switch to START and hold it there. If the meter reads above 0.2 volt, suspect bad contact at the solenoid battery cable stud.
- Connect the voltmeter leads to the battery negative terminal and a good ground on the engine. Turn the ignition switch to START and hold it there. If the meter reads above 0.2 volt, suspect bad connections of the battery negative cable or internal corrosion of the cable.
- Connect the positive (+) lead of the voltmeter to the starter motor housing and the negative meter lead to the battery's negative (-) terminal. Turn the ignition switch to START and hold it there. If the meter reads above 0.2 volt, suspect poor starter-to-engine ground.
- If the above tests do NOT reveal the cause of the problem, proceed to component tests, following in this section.