Mégane II vehicles are equipped with internally ventilated alternators with a built-in voltage regulator and a warning light that comes on and goes out when the ignition is turned on:
If the warning light comes on when the engine is running, there is a fault in the charging circuit.
Fig. Generator parts: 1 - casing, 2 - rear cover, 3 - tie bolt, 4 - connector, 5 - stator, 6 - front cover, 7 - pulley
Stator 5 (Fig. 1) and covers 2 and 6 are tightened with four bolts 3.
The rotor shaft rotates in bearings installed in covers 2 and 6.
Power is supplied to the rotor winding (excitation winding) through brushes and slip rings.
Three-phase alternating current induced in the stator winding is converted to direct current by a rectifier unit attached to rear cover 2.
Voltage for excitation of the generator when the ignition is turned on is supplied to the terminal of the voltage regulator.
Generator operation is monitored by a low battery indicator battery indicator located in the instrument cluster.
When the ignition is turned on, the indicator should light and go out after the engine starts if the alternator is working properly.
A bright or dimly lit indicator indicates a malfunction.
The accessory drive belt is tensioned by an automatic tensioner.
Possible alternator malfunctions and troubleshooting methods
Malfunction Troubleshooting
The low battery indicator does not light when the ignition is turned on:
Broken wire between the alternator, ignition switch (lock), and light - Repair the break
The low battery indicator does not go out after the engine starts:
Loss of tension on the alternator drive belt - Check and tighten the belt
Faulty alternator - Replace or Repair the alternator.
Short to ground in the wire between the alternator and the alarm - Insulate the wire.
The alternator is not charging the battery:
Battery terminals are corroded. - Clean, tighten, and lubricate the battery terminals and connections.
Battery defective - Replace the battery.
Alternator drive belt tension is loose - Check and replace the belt.
Alternator voltage regulator or rectifier unit defective - Replace the voltage regulator or rectifier unit.
Battery is overcharging (starting to boil):
Alternator voltage regulator or rectifier unit defective - Replace the voltage regulator or rectifier unit.
Increased voltage drop in the alternator-battery circuit - Check, clean, tighten, or replace the contact connections in the ignition switch, fuse and relay mounting blocks, connectors, and check the alternator housing ground connection.
Removing and Installing the Alternator.
Disconnecting the negative battery terminal
Pressing the wire connector retainer
Disconnecting the wiring harness
Unscrew the nut securing the red insulated wire tip Colors
Removing the wire end from the alternator stud
Removing the alternator drive belt - Replacing the accessory belt on a Renault Megane 2
Unscrew and remove the bolt securing the bracket to the alternator
Remove the nut securing the bracket to the cylinder block.
Remove the bracket.
Unscrew the upper generator mounting bolt.
Also unscrew the lower generator mounting bolt.
Extend the bolt to distance "A" (the bolt is removed in the picture).
Removing the alternator
Reinstalling the alternator in reverse order.
Tighten the alternator mounting bolts to the specified torque (25 Nm).
