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Mercedes-Benz C 240 Turn Signal Problems - How To Troubleshoot and Fix

Mercedes-Benz C 240 Turn Signal Symptoms

Your turn signal bulbs are an integral part of your life on the road, allowing you to indicate to fellow riders which direction you wish to turn. With a quick flip of your steering column's lever, the front and rear turn signal bulbs will flash.

With heavy wear and tear or short-circuiting, your turn signal may fail to flash, creating a serious safety hazard and grounds for being stopped by law enforcement. 

Keep reading below to understand how to troubleshoot turn signal problems, your Mercedes-Benz C 240 fuse box location, and instructions on how to replace your turn signal. 

Defective Turn Signal Switch

Your Mercedes-Benz C 240's turn signal switch is the lever on the upper right of the steering column. A faulty switch will not pass back a signal, often resulting from defective wiring or a defective switch mechanism. Sometimes, a broken clock spring may force it to lock into position. 

If you're repairing your Mercedes-Benz C 240's defective turn signal switch, it is very important to consult with your owner's manual's wiring diagrams. The manual will help you determine how to access your signal switch electrical connector. Sometimes, airbag systems need to be disabled before accessing the necessary parts. Accessing your turn signal switch electrical connector may also require removing your under-dash panel.

Dead Light Bulb

One of the most common reasons for defective turn signals on your Mercedes-Benz C 240 is a dead light bulb. With heavy use, turn signals will burn out, requiring a quick replacement. You can test this by turning your turn signal on then walking around the car to see which ones are not flashing. 

Broken Fuse

At times, your turn signal's fuse may blow out, the result of overheating, which can cut the current and short circuit it, preventing power from reading your light system. Like a dead light bulb, replacing a fuse is a relatively straightforward fix. Your fuse box is located under the dashboard on the driver's side, within the engine compartment. You can open its lid by pushing a tab downwards.

Turn Signal Lights Flash Intermittently, Too Fast or Too Slow

Your turn signal's erratic behavior is likely due to an incorrectly installed flasher or bulb, undercharged battery, or a loose turn signal switch connection. A burned-out bulb could also put the indicator light into overdrive. Address this with a quick visual check of the bulb's conditions, looking carefully for signs of damage. Check ground connections as well for possible shortages. 

A similar condition occurs when turn signal lights fail to turn off. Usually, this is a sign of a defective signal switch caused by a broken canceling finger or faulty clock spring, which may require complete reassembly. 

How To Replace Your Mercedes-Benz C 240 Turn Signal Bulb

To replace a defective turn signal bulb on your Mercedes-Benz C 240, perform the following steps. For this procedure, you will need a pair of safety glasses and work gloves.

  1. Park your powered-off vehicle on a flat surface and apply the emergency brake.
  2. Determine which of the turn signals is malfunctioning.
  3. Open your hood, remove your old turn signal bulb's electrical connector by easing down on the locking tab, and turn or pull the bulb socket counterclockwise to remove it. 
  4. Insert your new turn signal bulb by aligning your socket's slots with the bulb's alignment pins.
  5. Reassemble everything, turn on your vehicle, and flip the ignition switch lever to test your turn signal bulb.

If your affected turn signal is in the rear, the only difference in the instructions is to open your trunk or hatch and remove your tail light lens retaining screws. No matter what parts you need, you can get all the OEM Mercedes-Benz turn signal parts here.

This procedure is very easy to complete on your own. As a last resort, we recommend visiting a Mercedes-Benz technician or dealership for assistance.