The centre console switches on my 2012 Mercedes SLK200 are all inoperative, seat heating, hazard lights and auto stop/start. Is there a common fix?

Question edited for clarity and add maker.
Question moved to model category.

You need a mobile auto electrician. Diagnosis can only be done with a pro grade scan tool computer, the $3.5k to $5k type.

https://www.google.com/search?q=mobile+auto+electrician+near+me

Mercedes SAM - Signal Acquisition Module Explained

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SAM stands for Signal Acquisition Module. A SAM module (also called Signal Actuation Module) receives data from sensors, switches, and controllers, ...

The heated seats are powered by two fuses in the TIPM module under the hood. Fuse 31 & Fuse 33. The hazards are on a separate fuse

check your child lock circuit for failure

A electronic control module ,BCM body control module or a SJB - smart junction box ford calls their body control module .
Principles of Operation
The smart junction box (SJB) monitors the multifunction switch position by sending multiple voltage reference signals to the multifunction switch. When the multifunction switch is in the LH or RH TURN positions, or the hazard lamp switch is engaged, that input signal is routed to ground.
When the SJB receives a request for a turn signal or hazard lamps, the SJB supplies voltage to the appropriate turn lamps.

• The hazard lamps are inoperative/always on

• Circuitry
• Hazard lamp switch
• SJB

• Go To Pinpoint Test O

Pinpoint Test O: The Hazard Lamps Are Inoperative/Always On
Refer to Wiring Diagrams Cell 90 , Turn Signal/Stop/Hazard Lamps for schematic and connector information.
Normal Operation The smart junction box (SJB) sends a voltage reference signal to the hazard lamp switch through circuit CLS32 (BN/YE). When the hazard switch is engaged, the voltage signal is routed to ground through circuit GD116 (BK/VT). When the SJB detects a request for the hazard lamps, the SJB sends voltage to the appropriate turn lamps.
DTC B1875 - is an on-demand code that sets when the SJB detects a short to ground from the hazard lamp switch input circuit.

Possible Causes
• Circuit CLS32 (BN/YE) open or short to ground
• Circuit GD116 (BK/VT) open
• Hazard lamp switch
• SJB

Check the fuses first. If that's ok, it can be the sensor built into the mirror on the windshield, or the headlight switch itself.

probably have a look under passenger seat make sure all is conected

Check all.fuses and relays associated with your seats locations will be in owners manual.

I have a 2007 SLK200 can you tell me where and how to adjust the handbrake cables

Find out in your manual where your blinker switch is located, it is a cheap part. It is just a flasher, most likely that is what went out.

are you saying neither the heated seat cushion nor heated seated back on either seat works? But the light or lights does work?

Please rate as solved if this helps you. It took some time to dig all this stuff up. Please report progress.

Here's some info to start you off:

• The heated seat is inoperative — seat does not heat but the heated seat switch illuminates when pressed

• Circuitry.
• Heated seat module.
• Seat heater and temperature sensor.
• Seat back heater.
• Heated seat switch.