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Base Voltage Test
NOTE: Prior to running this test, turn the headlamp bulbs (13007) on for 10-15 seconds to remove any surface charge from the battery. Then, wait until the voltage stabilizes before performing the base voltage test.
With the ignition off and no electrical loads on, connect the negative (-) lead of Rotunda 73 Digital Multimeter 105-R0051, or equivalent, to the battery ground cable (14301) clamp.
Connect the positive (+) lead of the voltmeter to the battery to starter relay cable (14300) clamp.
Read and record the battery voltage shown on the voltmeter. This is called base voltage and will be used in later tests.
No-Load Test
Connect Rotunda 88 Digital Multimeter 105-R0053 or equivalent to monitor engine speed.
Connect the leads of Rotunda 73 Digital Multimeter 105-R0051 or equivalent across the battery terminals.
Read the voltage (base voltage).
Start the engine (6007).
Run the engine at 1500 rpm with no electrical load.
Read the voltage. The voltage should be in the range of 14.1 to 14.7 volts. If the voltage increase is less than 2.5 volts over the base voltage, perform the following Load Test. If there is no voltage increase or the voltage increase is greater than 2.5 volts, perform the Generator On-Vehicle Tests and Generator Bench Tests in the Diagnosis and Testing portion of this section.
Load Test
With the engine running, turn the air conditioner on, if equipped, the blower motor (18527) on high speed and the headlamps on high beam.
Increase the engine speed to approximately 2000 rpm. The voltage should increase a minimum of 0.5 volts above the base voltage. If the voltage does not increase as specified, refer to Generator On-Vehicle Tests and Generator Bench Tests in the Diagnosis and Testing portion of this section.
If the voltage increased as specified, the charging system is operating normally