Mercedes-Benz Electrical Diagnostics
Mercedes-Benz uses Signal Acquisition Modules (SAM — front and rear) for body control, the Electronic Ignition Switch (EIS/EZS) for immobiliser and drive-authorisation, and a Central Gateway (CGW) for network communication. COMAND/NTG infotainment, ESP stability and Keyless-Go all run on this architecture. Common faults include SAM body and power-supply faults, EIS/keyless issues, and battery/charging warnings. Diagnostics use XENTRY/DAS.
Mercedes-Benz Control Modules & Electronics
Key modules and electronic systems used across Mercedes-Benz vehicles. Correct identification of the module is the first step in proper diagnosis.
SAM — Signal Acquisition Module
Front and rear SAMs handle body electronics and power distribution.
EIS / EZS — Electronic Ignition Switch
Immobiliser and drive-authorisation; key and no-start faults.
CGW — Central Gateway
Network gateway; communication faults cause multiple warnings.
ME — Motor Electronics
Engine management ECU.
ESP — Stability Program
ABS, traction and stability control.
COMAND / NTG Infotainment
Head unit and connectivity faults.
Keyless-Go
Keyless entry and start.
Common Mercedes-Benz Electrical Faults
Faults we frequently see on Mercedes-Benz vehicles. Each links to a detailed, all-makes guide covering symptoms, causes and our diagnostic approach.
Body Control Module (BCM) Faults
Central body electronics controlling locking, lighting, wipers and comfort.
READ GUIDEKey Not Detected
Vehicle doesn't recognise the key — won't start or unlock.
READ GUIDEABS Warning Light
ABS warning on — stability and braking-system fault.
READ GUIDEBattery Warning Light & Vehicle Not Charging
Charging-system fault — battery warning or vehicle not charging.
READ GUIDEParking Assist Unavailable
Parking sensors or park assist not working.
READ GUIDEAirbag / SRS Warning Light
Airbag or SRS warning light on — restraint-system fault.
READ GUIDEElectric Power Steering Fault
EPS warning — steering assistance reduced or unavailable.
READ GUIDEAir Suspension Faults
Air-suspension warning — ride-height or compressor fault.
READ GUIDECAN Bus / Network Communication Faults
Network communication fault affecting multiple modules.
READ GUIDEMercedes-Benz Models We Cover
Mercedes-Benz Electrical Fault?.
Tell us about your Mercedes-Benz, the symptoms and any warning messages. OBD_PAL diagnoses the complete system before recommending any repair — don't guess, diagnose it properly.