Replacing the voltage regulator (BMW 5 Series E28)

The voltage regulator controls the charging system by limiting the generator's output voltage. The regulator is a sealed unit and is not adjustable.

If the voltmeter shows that charging is not occurring (or if the charge/ignition control lamp is on) and the alternator, battery, belt tension and electrical connections seem OK, have the voltage regulator checked by the dealer or an electrician.

Disconnect the negative battery cable.

If your car radio has an anti-theft system, make sure you know the correct activation code before disconnecting the battery. Refer to Section 1 for information before disconnecting the wire Anti-theft audio system and instrument cluster language.

If a message in another language appears on the instrument panel display after connecting the battery, refer to Section 1 for the language setting procedure Anti-theft audio system and instrument cluster language.

Bosch Generator

The voltage regulator is mounted on the outside of the generator housing. To replace the regulator, unscrew the nuts and remove the small terminal cap from the generator cover, then unscrew the nuts and remove the cover.





On Bosch generators, the voltage regulator is easy to remove. This type of regulator is integrated with the brush assembly.

Installation is the reverse of removal.

Before installing the voltage regulator, check the condition of the collector rings. Using a flashlight, check for grooves and deep wear grooves. Replace the generator if necessary.

Motorola Generator

1. Remove the generator from the engine (see section Removal and installation the generator).

2. Remove the back cover and diode rectifier, unscrew the screws securing the voltage regulator and separate the regulator from the generator body.

3. Installation is the reverse of removal.