How To Do A Starter Draw Test

Current Draw Test

A starter current draw test provides a quick check of the entire starting system. With the Sun VAT-40 tester, it also checks battery's cranking voltage. If another type of tester is used, follow the manufacturer's recommended procedure.

The starting current draw and cranking voltage should meet the specifications listed for the Toyota model being tested. Typical current draw specs are 130-150 amps for 4-cylinder models and 175 amps for 6-cylinder models. Cranking voltage specs range from 9.6 to 11 volts. Always refer to the correct repair manual. Only perform the test with the engine at operating temperature.

The following steps outline a typical procedure for performing a current draw test on a starting system:

1. This test should be made only with a serviceable battery. The specific gravity readings at 800°F should average at least 1. 190 (50% charged). Charge the battery, if necessary.

2. Prepare the tester:

• Rotate the Load Increase control to OFF.

• Check each meter's mechanical zero. Adjust, if necessary.

• Connect the tester Load Leads to the battery terminals; RED to positive, BLACK to negative.

NOTE: Battery open-circuit voltage should be at least 12.2 volts (50% charged). If not, the battery requires charging.

• Set Volt Selector to INT 18V. Tester voltmeter should indicate battery open-circuit voltage.

• Set Test Selector to #2 CHARGING.

• Adjust ammeter to read ZERO using the electrical Zero Adjust control.

3. Connect the clamp-on Amps Pickup around the battery ground cable or cables.

4. Make sure all lights and accessories are off and vehicle doors are closed.

5. Set the Test Selector switch to #1 STARTING.

6. Disable the ignition so the engine does not start during testing.

7. Crank the engine, while observing the tester ammeter and voltmeter.

• Cranking speed should be normal (200-250 rpm).

• Current draw should not exceed the maximum specified.

• Cranking voltage should be at or above the minimum specified.

8. Restore the engine to starting condition and remove tester leads.

TEST RESULTS: High current draw and low cranking speed usually indicate a faulty starter. High current draw may also be caused by engine problems. A low cranking speed with low current draw, but high cranking voltage, usually indicates excessive resistance in the starter circuit. Remember that the battery must be fully charged and its connections tight to insure accurate results

Voltmeter Battery Current Drain Test

Continue reading here: Voltagedrop Tests

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