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.
Current Consumption
CLK class, E class and SL500 models, disconnect fuel pump relay (K27). Connect DVOM to fuel pump relay socket terminals No. 2 and 8. On CLK class and SL500 models, fuel pump relay (K27) is located in right front corner of trunk. On E class models, fuel pump relay (K27) is located under right side rear seat cushion, near battery. On ML430, disconnect fuel pump relay (k3). Connect DVOM to fuel pump relay socket terminals No. 3 and 5. On ML430, fuel pump relay (k3) is located in fuse and relay module (F1). Fuse and relay module (F1) is located in left rear corner of engine compartment. On all models, turn ignition on. DVOM should indicate 4-9 amps. If amperage is within specification, test is complete. If amperage is not within specification, possible cause is faulty fuel pump. Repair as necessary.
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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.