Mercedes-Benz ML320. Manual — part 354

2001 Mercedes-Benz ML320

2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis

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Fig. 8: Connecting Hand Held Tester Scan Tool To OBD-II Data Link Connector
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ON-VEHICLE TESTING

WIRING CONTINUITY

1. Connect voltmeter between generator B+ terminal and ground. Voltmeter should indicate battery voltage.

If battery voltage is not indicated, check battery and check wiring between generator and battery for
corrosion, loose terminals, etc.

2. Turn ignition on and ensure instrument cluster charge indicator light (battery symbol) comes on. If light

does not come on, check wiring between generator and warning light, including indicator bulb.

GENERATOR OUTPUT

1. Ensure connections at battery and generator are clean and tight. Ensure generator, engine and body are

properly grounded. Ensure generator drive belt is properly adjusted and in good condition.

2. Connect load tester/ammeter as per tester manufacturer's instructions. Connect voltmeter leads to battery

terminals. See Fig. 9 . Start engine and run at 2200 RPM for V6 or 2500 RPM for V8. Adjust load tester
to obtain maximum generator output. DO NOT allow voltage to drop to less than 12.7 volts.

3. Maximum generator output should be within a few amps of generator rated output stamped on generator.

If output is not within a few amps of generator rated output, check generator diodes. See DIODE TEST .
Replace generator as necessary.

2001 Mercedes-Benz ML320

2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis

me

Fig. 9: Checking Generator Output (Chassis 163)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

2001 Mercedes-Benz ML320

2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis

me

VOLTAGE REGULATOR CONTROL

1. Connect multimeter. See Fig. 10 . Ensure charge indicator light goes out when engine is idling and with

increasing engine speed up to 3000 RPM. Apply load to battery by turning on headlights and noting
reading after 2 minutes.

2. Voltage reading should be 13-14.5 volts. If voltage is not to specification, replace voltage regulator. See

VOLTAGE REGULATOR under REMOVAL & INSTALLATION. If regulator is okay, replace
generator. See GENERATOR under REMOVAL & INSTALLATION.

2001 Mercedes-Benz ML320

2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis

me