PROJEKT36 · WIRING

EWS immobiliser

How the E36 immobiliser checks the key and then releases the starter and the DME, redrawn with the real wire colours. Hover or tap a wire to follow it through every connector; tap a part for what it does.

Standard petrol E36, 316i–328i. EWS II from the 1998 BMW wiring manual (built from 1/1995); EWS I as a signal-flow view. On a phone, scroll the diagram sideways.

projekt36.com/wiring/ews/

SW blackRT redGN greenBL blueGE yellowBR brownWS white GN/SW = green with black stripe supply / ground of a part shown elsewhere colour not given in the source

EWS II immobiliser

X10018 · 2 X10017 · 16 X511 · 5 0.5 BR/SW X511 · 7 X191 to EGS 0.35 WS/VI diagnostic link 0670.5 X10018 · 30 X1660 · 2 X10010 0.35 BL X1660 · 1 X90260 · 1, 3 4 RT X33 · 1 X209 · 5 2.5 SW/GE2.5 GN/SW X209 · 4 X33 · 8 X173 0.5 SW/GN X10182 · 15 0.5 BL/RT/GE X14 · 4 X450 remote ZV/DWA 6610.2 X10102 · 6 X1047 from DME 0.5 GN · SW/VI on 4-cyl X20 · 7 0.35 SW/GN X1071 · 1 2.5 SW/GE X20 · 18 X6810 X6510 P90 Front power distribution box F31 5A terminal 30 · F28 5A terminal 15 · F45 7.5A radio position (R) F31 F28 F45 X2 S3 Gear selector lever switch 0 low (off) · 1 high (on) 5 7 A835 Transmit/receive module talks to the key transponder R 31 S/E 1 3 Antenna Ring antenna around the ignition lock S2 Ignition switch 0 off · 1 radio2 ignition · 3 START 30 50 A836 EWS II immobiliser control unit connector X1659 · starter relay insidechecks the key code, then enables starter and DME 5 9 2 13 3 7 8 14 12 4 15 1 A104 ZKE control unit or A30 ZVM 15 A2w Instrument cluster 20 N4 On-board computer 1 A194y Remote control unit 6 A6000 DME control unit immobilising input 18 / 81 M6510 Starter 50

How it works

Turning the key powers the ring antenna around the ignition lock. The transmit/receive module reads the transponder chip in the key and passes the code to the EWS unit on the S/E line (pin 13).

Only with a valid key does EWS do two things: it closes its internal starter relay, so the START signal from the ignition switch (pin 3) reaches starter terminal 50 (pin 1), and it sends an enable code to the DME (pin 4). Without that code the DME will not run the engine.

EWS also exchanges data with the central locking (pin 8), the remote-control unit (pin 14) and the on-board computer (pin 15), and reads engine speed on pin 12. On automatics it needs the start-enable signal from the gear selector lever switch on pin 9.

Check on your car

  • This is EWS II, fitted from 1/1995. Cars built from 1/1994 to 12/1994 have the first-generation EWS (signal flow below); neither the 1998 BMW manual nor Bentley has a wiring diagram for it.
  • The DME pin numbers here (pin 18 on the M52 six-cylinders, 81 on the 316i/318i, 10 on the 318is) are for the 1998 engines. An M50 DME (M3.1 or M3.3.1) is wired differently; check before an engine swap.

Redrawn from BMW ETM 6135.0-00 and 6135.0-01 (05/99), standard petrol E36 (316i–328i); diesel and M3 parts are left out.

EWS I (built 1/1994–12/1994): signal flow

S2 Ignition switch START signal (terminal 50) GM General module (ZKE) double-lock status OBC On-board computer code function Auto Range switch park / neutral EWS I Starter immobilisation relay left of the steering columnno key transponder DME Engine control blocks injection and ignitionwhen told to M6510 Starter 50

How it works

The first-generation EWS has no key transponder. It is a "smart" starter relay that only passes the START signal to the starter when its inputs allow it, and it tells the DME to block injection and ignition otherwise.

It blocks starting when the car is double-locked from outside (General Module signal), when the on-board computer code function is set, and on automatics when the gearbox is not in park or neutral.

From production 6/94 it also reads the DME engine speed signal and opens the starter contact above 60 Hz, protecting the starter. Cars built before 6/94 do not have this input.

Check on your car

  • This view shows which unit feeds which, not the wiring: pin numbers and wire colours for EWS I are not in the sources used here.

Redrawn from Micro-Tronik, EWS I system components (functional description, no pinout); diesel and M3 parts are left out.

Reading the wire codes

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.