# Group 12 Engine Electrical Index

Alternator - Bearing, replace
Alternator - Carbon brushes, replace
Alternator - Diode plate, replace
Alternator - Disassemble and assemble
Alternator - Voltage regulator, replace

Diagnostic connector - Pin layout

Distributor - Cap and Rotor, remove and install

DME - Engine control unit, remove and install
DME - Engine electronics system description

Ignition Coil - Check or replace

Spark Plug - Wires, repair

Starter Motor - Operating principles
Starter Motor - Remove and Install
Starter Motor - Troubleshooting

### Important information for working on transistorized ignition systems and Digital Motor Electronics (DME)

Always disconnect battery or interrupt power supply to ignition control unit and ignition coil when working on the electrical system (charging battery or welding, etc.) Dangerous primary and secondary voltage can occur, causing injury, or more likely, damage to electronic components.

| Never crank engine with coil lead disconnected unless lead is grounded, or DME is disconnected.
| Never disconnect the battery or alternator leads while the engine is running.
| Never connect wire of ignition coil terminal 1 to ground or B+. Also, never install an anti theft system that breaks the wire to terminal 1 of the coil as a kill switch.
| When performing compression check, disconnect DME or remove Main Relay

The secondary side (high voltage side) of the ignition system must be shielded with at least 4K Ohms. Always use a distributor rotor of original specification of 1 K Ohm. Do not use a higher resistance rotor to solve radio interference. Use suppressers instead.

| Always completely disconnect any component or harness before checking with an Ohm meter, or value will be incorrect.

E30 M3 Repair Manual V2.7. Copyright ©1999-2001 Koala Motorsport & Brett Anderson