What is the reason why the Mercedes-Benz car does not power on when the key is inserted?
2 Answers
Failure to power on when the key is inserted may be due to a dead key battery or wiring issues. Relevant knowledge is as follows: Specific reasons: First, check whether the live wire entering the ignition switch has power. If it does, the part before the ignition switch is normal; if not, there is a fault before the ignition switch. Check whether the wire connections are loose, detached, corroded, or poorly connected. Then, insert the key and turn it to the ignition position without moving it, and check whether the live wire of the starter motor solenoid has power. If not, the ignition switch is faulty; if it does, continue to check whether the solenoid is faulty—check whether the solenoid coil is open, and whether the wires and connections are loose, corroded, or poorly connected. Inspection steps: Check whether the dashboard and indicator lights, especially the detection switches on the machine, respond when the power is turned on. If not, inspect the switches, battery, wiring harness, etc. If they do, proceed to the next step. When attempting to start the engine, check whether the starter makes a clicking sound. If it does, inspect the starter and power supply; if not, check the wiring harness, fuses, key switch, etc. If the starter rotates normally, inspect the fuel system, high-voltage circuit, fuses, spark plugs, timing components (including the distributor, etc.), or even consider whether the engine requires an overhaul.
I've been running a Mercedes repair shop for nearly twenty years, and there are several common issues when the key doesn't power on. The key battery is depleted—Mercedes smart keys use button batteries, and when the charge is low, the signal can't be transmitted. Simply use the spare key or replace the battery. A faulty main vehicle battery is more serious, possibly due to aging, loose connections, or excessive discharge. If a multimeter shows voltage below 12V, it's dangerous. Next, check the fuse box—the ignition system fuse is under the dashboard, and a blown fuse often causes no power. Additionally, a damaged ignition switch or activated anti-theft system can lock the system due to module errors. In such cases, visit a dealership for computer diagnostics and reset. Avoid DIY fixes—safety first. Visit a professional shop early to prevent further damage, especially since Mercedes high-end cars have complex wiring prone to major issues. Regular maintenance checks on the battery and key lifespan are crucial.
