Oldsmobile starter motor testing?

The starting, or cranking system consists of the battery, starter motor, ignition switch and related wiring. These components are connected electrically. When the ignition switch is turned to theSTART position (and the theft protection module recognizes the key code, as equipped) battery voltage is applied to the starter solenoid (through the theft deterrent relay, as equipped) S terminal and the solenoid windings are energized. This causes the plunger to move the shift lever, which engages the pinion with the engine flywheel ring gear. The plunger also closes the solenoid contacts, applying battery voltage to the starter motor, which cranks the engine.

When the engine starts, the pinion will over-run and spin at engine speed (rather than starter motor speed) to help prevent flywheel and starter motor damage. When the ignition switch is released (removing the voltage from the solenoid) the plunger return spring disengages the pinion. In order to prevent excessive over-run, the ignition switch should be released as soon as the engine starts.

WARNING

Never operate the starter motor for more than 30 seconds at a time. Allow it to cool for at least two minutes. Overheating, caused by too much cranking, will damage the starter motor.

The vehicles covered by this guide use several different starter motor applications. When obtaining a replacement starter motor, make sure you get the correct unit. In nearly every case, the starter motor is considered non-serviceable which means they are not user-serviceable and must be replaced as an assembly.

Starter motors do not require lubrication. In general, starter motors give little trouble. Most no-start or hard cranking complaints can be traced to a low battery, poor connections, defective fusible link, engine oil too thick for the weather conditions and other non-starter related causes.

Although different starter motors are used on different engines, the removal and installation procedures are very similar. The main differences are getting to the starter (air dam removal or radiator baffle removal requirements on some applications).

TESTING

Before removing any component of the cranking circuit, check the following:

Inspect the battery and cables, as outlined in .

Inspect the wiring for damage

Inspect all connections to the starter motor, solenoid, ignition switch, battery and all ground connections. Clean and tighten as required.

Inspect the starter motor and ignition switches to determine their condition.

If the battery, wiring and switches are in satisfactory condition, and the engine is known to be functioning properly, the starter may be at fault.

Voltage Drop Test

NOTE

The battery must be in good condition and fully charged prior to performing this test.

1. Disable the ignition system by unplugging the coil pack. Verify that the vehicle will not start.
2. Connect a voltmeter between the positive terminal of the battery and the starter B+ circuit.
3. Turn the ignition key to the START position and note the voltage on the meter.
4. If voltage reads 0.5 volts or more, there is high resistance in the starter cables or the cable ground, repair as necessary. If the voltage reading is ok proceed to the next step.
5. Connect a voltmeter between the positive terminal of the battery and the starter M circuit.
6. Turn the ignition key to the START position and note the voltage on the meter.
7. If voltage reads 0.5 volts or more, there is high resistance in the starter. Repair or replace the starter as necessary.

NOTE

Many automotive parts stores have starter bench testers available for use by customers. A starter bench test is the most definitive way to determine the condition of your starter.

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