1997 MERCEDES-BENZ ML500 charging

2001 Mercedes-Benz ML320
2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis
me
Saturday, October 02, 2010 3:20:32 PMPage 11 © 2006 Mitchell Repair Information Company, LLC.

Fig. 7: Connecting Hand Held Tester Scan Tool To Mercedes-Benz Data Link Connector
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

2001 Mercedes-Benz ML320
2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis
me
Saturday, October 02, 2010 3:20:32 PMPage 12 © 2006 Mitchell Repair Information Company, LLC.

2001 Mercedes-Benz ML320
2001-04 STARTING & CHARGING SYSTEMS Gene rators & Regulators - 163 Chassis
me
Saturday, October 02, 2010 3:20:32 PMPage 13 © 2006 Mitchell Repair Information Company, LLC.

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
Saturday, October 02, 2010 3:20:32 PMPage 14 © 2006 Mitchell Repair Information Company, LLC.

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
Saturday, October 02, 2010 3:20:32 PMPage 15 © 2006 Mitchell Repair Information Company, LLC.

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
Saturday, October 02, 2010 3:20:32 PMPage 16 © 2006 Mitchell Repair Information Company, LLC.

Fig. 10: Checking Voltage Regulator (Chassis 163)
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
DIODE TEST

2001 Mercedes-Benz ML320
2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis
me
Saturday, October 02, 2010 3:20:32 PMPage 17 © 2006 Mitchell Repair Information Company, LLC.

Connect DC clip-on probe from engine tester with oscilloscope to positive battery terminal. See Fig. 11. Start
engine. Switch on low beam. Access diode test at 3000 RPM. See Fig. 12
-Fig. 14 . Replace generator as
necessar
y.

2001 Mercedes-Benz ML320
2001-04 STARTING & CHARGING SYSTEMS Generators & Regulators - 163 Chassis
me
Saturday, October 02, 2010 3:20:32 PMPage 18 © 2006 Mitchell Repair Information Company, LLC.