TL;DR

  • E36 wiring diagrams come in two forms: BMW’s own ETM (German colour abbreviations such as SW, BR, RT) and the redrawn diagrams in the Bentley manual (English abbreviations such as BLK, BRN, RED). Both show the same circuits.
  • Learn the terminal numbers: 30 (battery, always live), 15 (ignition on), 31 (ground), 50 (starter), 85/86/87 (relays).
  • Trace a circuit from power, through fuse, switch and load, to ground, then test it with a digital multimeter or LED test light, never a bulb test lamp.

What’s in the diagrams

Bentley’s Electrical Wiring Diagrams section covers the 1992–1998 E36 by system, for example: Power Distribution, Ground Distribution, Starting, Charging System, Engine Management, Exterior Lights, Headlights/Foglights, Instrument Panel, Power Windows, Power Door Locks, Anti-Theft (EWS II), ABS and many more. Many systems have several versions by model and year: first find the diagram that matches your car’s model, engine and build date.

Fuse, relay and ground locations are in a separate part of the manual (610 Electrical Component Locations), not on the diagrams themselves.

Wire colours

A combined code means a coloured wire with a stripe: Bentley’s example is BLU/RED, a blue wire with a red stripe. BMW’s own ETM uses German abbreviations and often adds the cross-section in mm² before the colour (for example 0.75 BL/RT).

ColourBMW (German)Bentley
BlackSW (schwarz)BLK
BrownBR (braun)BRN
RedRT (rot)RED
YellowGE (gelb)YEL
GreenGN (grün)GRN
BlueBL (blau)BLU
VioletVI (violett)VIO
GreyGR (grau)GRY
WhiteWS (weiß)WHT
OrangeOR (orange)ORG
PinkRS (rosa)PNK

On BMWs, brown wires are normally grounds. Bentley also notes that a wire in the car can be a different colour from the diagram: what matters is that it connects the right terminals.

Terminal numbers (Bentley Table a)

TerminalMeaning
1Low-voltage switched terminal of the ignition coil
4High-voltage centre terminal of the coil
15From the ignition switch: live in RUN and START
30Battery positive: live whenever the battery is connected, independent of the ignition switch
31Ground, battery negative
50Starter solenoid feed, START position only
85Relay coil, ground side
86Relay coil, power-in side
87Relay switched contact
D+Alternator warning light and field energising circuit

These are the standard German (DIN) terminal designations: you’ll see “Kl. 30”, “Kl. 15” (Klemme, terminal) in German sources.

A switched circuit and a relay with their terminal numbers Left: battery positive, terminal 30, feeds a fuse, a switch and a load, which returns to ground, terminal 31. Right: a relay. The coil sits between terminal 86, power in, and 85, ground side. When the coil is energised, the contact connects terminal 30 to 87, which feeds the load. Simple circuit Battery + 30 fuse switch load ground 31 Relay power in (+) 86 coil 85 ground side supply 30 87 to load Terminal numbers per Bentley 600, Table a (DIN). 15 is the ignition-switched feed (RUN and START).
How terminal numbers appear in a circuit: 30 always live, through fuse, switch and load to 31 ground. A relay's coil (86, 85) switches the heavy contact from 30 to 87.

Numbers on the diagram

Components, connectors, fuses and ground points each have their own identification number, which corresponds to that part throughout the diagrams. Ground points are numbered G100, G101, G102…, and their locations are listed in the ground distribution guide. Fuses are numbered as in the fuse and relay reference.

Most component terminals are also numbered on the part and on its connector, so the pin on the diagram is the pin you probe.

Tracing a circuit, step by step

  1. Pick the right diagram for the system, your model and build date.
  2. Start at the fuse feeding the circuit: is it fed from 30 (always live) or 15 (ignition on)?
  3. Follow the wire through switches, relays and connectors to the load (bulb, motor, module), noting colours and connector numbers.
  4. Follow it to ground: which G-number, and where is it in the car?
  5. Test with the circuit live: voltage at the load’s supply, then a voltage drop test across switches, connectors and the ground. A good ground side reads close to 0 V.
  6. Test with the circuit dead: continuity only with the battery disconnected.

Bentley’s tool rules: use a digital multimeter with at least 10 MΩ input impedance or an LED test light. A bulb test lamp or an old analogue meter can draw enough current to damage control modules, and an ohmmeter must never be used on solid-state components such as control units.

Safety

  • Disconnect the battery before removing electrical components. That can erase stored fault codes, so read them first.
  • Airbag cars: follow the airbag precautions before any electrical work near the system.
  • Connect and disconnect connectors and test leads only with the ignition off.
  • Use jumper wires with flat-blade ends of the right size, so you don’t spread the terminals and create a new intermittent fault.