Generator & Regulator Switch

Check for correct connections on fully charged battery, generator and starter motor. Check for good ground connection between engine and body. Check for properly tightened drive belt. Connect DIS tester. Search down through the following:

• FUNCTION SELECTION
• COMPLETE VEHICLE
• DRIVE
• VOLTAGE AND CURRENT REGULATION
• VOLTAGE AND CURRENT GENERATION

Work through test modules. To diagnose oscillograms for each fault, see GENERATOR OSCILLOGRAMS . If generator is faulty, repair or replace it. To replace generator on 3.0L (M54), see GENERATOR 3.0L (M54)  under REMOVAL & INSTALLATION. To replace generator on 4.4L & 4.6L (M62), see GENERATOR 4.4L & 4.6L (M62)  under REMOVAL & INSTALLATION. To replace generator on 4.4L (N62), see GENERATOR 4.4L (N62)  under REMOVAL & INSTALLATION.

If regulator is faulty, replace it. To replace Bosch regulator, see VOLTAGE REGULATOR (BOSCH) . To replace Valeo regulator, see VOLTAGE REGULATOR (VALEO) . To replace regulator on 4.4L (N62) see VOLTAGE REGULATOR 4.4L (N62) .

Fault	Oscillogram
Fault-Free	See Fig 1
One Phase Interrupted	See Fig 2
Internal Fault	See Fig 3
Open Circuit In Negative Diode	See Fig 4
Short Circuit In Positive Diode	See Fig 5
Open Circuit In Positive Diode	See Fig 6
Open Circuit In Exciter Diode	See Fig 7