Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
9. System interconnections
Various functions in the central body electrics, the anti-theft alarm system (DWA) and the electronic immobiliser (EWS) can be activated or deactivated by means of the radio transmitters.
During vehicle diagnosis, it is important to know how the radio transmitter influences the total system.
| Component | Designation |
|---|---|
| Z | Ignition lock, electromechanical part |
| EWSIII | Electronic immobiliser, control unit |
| EWSIII/1 | Output - starter signal (X1659) |
| EWSIII/3 | Input - ignition/starter switch signal (X1659) |
| EWSIII/4 | Output - engine control unit signal, uni-directional (X1659) |
| EWSIII/5 | Output - ring coil signal (X1659) |
| EWSIII/6 | Input - transmission control unit switch signal (X1659) |
| EWSIII/9 | Ground/earth (X1659) |
| EWSIII/10 | Input - terminal 30 of fuse F67 (X1659) |
| EWSIII/11 | Input - terminal R from ignition lock via fuse F14 (X1659) |
| EWSIII/12 | Output - ring coil signal (X1659) |
| EWSIII/13 | Input/output - K bus signal (X1659) |
| F9 | Terminal 30/5A fuse |
| F46 | Terminal 30/30A fuse |
| F49 | Terminal 30/5A fuse |
| F67 | Terminal 30/5A fuse |
| LSZ | Central light switch |
| LSZ/21 | Input/output K bus (X12) |
| LSZ/31 | Ground/earth (X12) |
| LSZ/47 | Output - search light signal (58g) (X12) |
| ILV | Interior lighting, front |
| ACS | Automatic transmission control unit |
| DME/DDE | Digital Engine Electronics/Digital Diesel Electronics |
| DME/33 | Input - EWS release signal (X6004) |
| CAN | Controller Area Network (CAN bus) |
| K-Bus | Bodyshell bus |
| FH | Window lift (stands for all window lifts in vehicle) |
| SHDM | Sunroof module |
| SMT | Lock module (stands for all doors) |
| HK | Luggage compartment lid motor |
| TK | Fuel filler cap drive |
| USIS | Ultrasonic interior protection |
| NG | Tilt sensor |
| FZV | Radio central locking receiver |
| FZV/1 | Input - terminal 30 signal of fuse F49 (X1143) |
| FZV/2 | Ground/earth - (X1143) |
| FVZ/3 | Input/output - radio transmitter signal (X1153) |
| GM | General module V |
| GM/3 | Output - electric consumer cut-out signal (X332) |
| GM/5 | Output - tilt sensor monitoring signal (X254) |
| GM/6 | Input - tilt sensor monitoring, immobiliser signal (X254) |
| GM/8 | Input - interior lighting switch signal, front, continuous operation (X253) |
| GM/8 | Output - control signal, DWA emergency power siren alarm (X254) |
| GM/9 | Input/output - K bus signal (X253) |
| GM/10 | Ground/earth (X253) |
| GM/17 | Output - luggage compartment lid unlocking motor signal to luggage compartment lid drive (X253) |
| GM/18 | Input - interior lighting signal (X253) |
| GM/23 | Output - DWA light emitting diode signal (X254) |
| GM/24 | Input - passenger-compartment sensor signal (USIS) (X254) |
| GM/27 | Input - terminal R of fuse F9 (X253) |
| GM/35 | Output - fuel filler cap unlocking signal (X253) |
| GM/42 | Input - luggage compartment lid contact signal from luggage compartment lid drive (X253) |
| GM/47 | Input - terminal 30 signal of fuse F49 (X253) |
| GM/49 | Input/output - radio remote control data line signal (X253) |
| GM/50 | Output - fuel filler cap locking signal (X253) |
| TXD | Diagnostic bus to diagnostic connector |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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