The E36 starter and alternator circuits, redrawn with the real wire colours. Hover or tap a wire to follow it through every connector; tap a part for what it does.
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Turning the key to START (position 3) sends battery voltage from ignition switch terminal 50 to the EWS II unit, not straight to the starter.
The starter relay sits inside EWS II. It only closes when the key code is accepted. On automatics, EWS also takes a start-enable signal from the gear selector lever switch S3.
With the relay closed, the black/yellow wire energises the starter solenoid (terminal 50), which connects the 25 mm² battery cable (terminal 30) to the starter motor.
While the starter turns, terminal 30h signals the body electronics, climate control and on-board computer.
Redrawn from BMW ETM 1240.0-00 and 1240.0-01 (05/99), standard petrol E36 (316i–328i); diesel and M3 parts are left out. Not covered: cars built before 1/1995, which have the first-generation EWS instead of EWS II.
With the ignition on, terminal 15 feeds the charge warning lamp in the cluster. The lamp's other side runs to alternator D+, so current through the lamp excites the regulator and the lamp lights.
Once the engine runs and the alternator charges, D+ rises to system voltage. Both sides of the lamp are then at the same voltage, so it goes out.
The charging current itself leaves through B+ to the starter's terminal 30 stud and from there into the battery cable.
If the lamp never lights with the ignition on, the alternator may not be excited at all: check the bulb and this D+ wire. If it stays on with the engine running, the alternator is not charging.
Redrawn from BMW ETM 1230.0-01 (05/99), standard petrol E36 (316i–328i); diesel and M3 parts are left out.
BMW labels every wire with its size and colour, for example 2.5 SW/GE: 2.5 mm², black (schwarz) with a yellow (gelb) stripe. Connectors are numbered X…, followed by the pin. The wires in these diagrams are drawn at relative thickness, so the 25 mm² battery cable stands out from a 0.35 mm² signal wire.
Codes used here: SW = black, RT = red, GN = green, BL = blue, GE = yellow, BR = brown, WS = white.