Mercedes turn signal not working

Last updated: October 27, 2026

In this article, we will discuss the most common Mercedes turn signal problems and how to diagnose them yourself. If your left or right turn signals (side mirror, headlight, or tail light) have stopped working, the problem may be caused by a faulty SAM module, combination switch, blown fuse, or bad relay.

Problem

• The left or right Mercedes turn signal is NOT working.
• All Mercedes turn signals don’t work.
• The turn signal doesn’t work after installing a new bulb

In newer Mercedes models, you will get a warning on the instrument cluster stating, “Turn Signal Left / Right / Front / Rear / Side Malfunction.” Depending on the Mercedes model and problem, a warning may or may not show on the dashboard.

Before you start!

Always start by double-checking the turn signal light bulb. Make sure it is installed properly in the turn signal socket. Replace them if they are burned or have corroded contacts. Replacing turn signal bulbs with new ones with the correct wattage is important. Check the recommended turn signal bulb type and wattage in the owner’s manual.

Common Mercedes Turn Signal Problems

1. Front or Rear Mercedes Turn signals not working
2. Left or Right Turn signals are not working
3. Turn Signals and Emergency Hazard Flasher Inoperable

Mercedes turn signal won’t work. First things to check!

1. Check the turn signal fuses in your fuse panel under the dash and engine compartment. Look in the owner’s manual to find the location of the fuse panels for your Mercedes.

2. Test or replace the turn signal relay. Swap the turn signal relay with another relay in the identical fuse box. Does the problem follow the relay?

3. Press the hazard warning switch on and off several times. The switch can get stuck and prohibit the turn signals from operating properly.

1. Left or Right Mercedes Turn signal not working

Problem:

Mercedes’s turn signal is not working. It could be one of the turn signals located in the front, rear, or side mirror housing.

Cause:

Any of the following may cause Mercedes turn signal not working problems:

• a bad headlight/taillight electrical plug/connector/harness
• burned turn signal contact may heat up and melt the plastic that covers the contact points.
• A bad SAM module
• a burned light bulb

Solution:
Replace the light bulb with a new bulb that has the recommended wattage and bulb type.

The electrical plug that plugs into the headlight or taillight assembly may be loose or not making good contact. Remove the electrical plug from the turn signal unit that is not working and inspect it. Clean it electrical contact cleaner if necessary.

We have seen cases where the turn signal stopped working due to inadequate electrical contact between the turn signal bulb socket and the headlamp housing. The socket contact points heat up to the point where they start to melt. If this is your problem, try using sandpaper to clean and reinstall the socket.If the turn signal fails within a few weeks, replace the socket or the turn signal assembly if necessary. If you keep having the problem of the turn signal socket melting, try adding a ground from the tail light to the frame.

Check for power at the turn signal assembly.

1. You need to use a digital multimeter to test for power at the headlight/taillight.
2. Set the meter to DC VOLTS. Not current, not amps.
3. Turn the turn signal switch or hazard lights on.
4. Put the black probe on a good chassis ground and touch the red probe to the power side of the socket. You are looking for roughly 11 to 14 volts, pulsing in time with the flash.

You should get between 11 and 14 volts if you don’t get any power check continuity between the turn signal and the SAM module.

If you don’t get any power, check the continuity between the turn signal and the SAM module. Here is a good article on how to perform this test on a Mercedes-Benz.

Diagnose the SAM module and replace it if necessary. If you are a Mercedes owner trying to troubleshoot the problem yourself, read codes with the YOUCANIC full system scanner. Mercedes-Benz cars have two or more SAM units.

• Left front SAM (N10/6) powers left front lights
• Right front SAM (N10/7) powers right front lights

It is not common for both of these SAM units to fail simultaneously. It’s typically one or the other.

Mercedes (left or right) turn signal constantly ON

A defective SAM module can cause one turn signal to stay on all the time while the rest operate properly.

2. Left or Right Turn signals not working

Problem:

• Turn signals on one side (left or right) of the car are not working. When you press the switch to turn left (or right), none of the turn signals on one side work.
• Turn signal light doesn’t stay on. The turn signal switch doesn’t engage to keep the left or right turn signal on. You can manually hold the turn signal switch pressed to keep the turn signal flashing.

Cause:

In most cases, these turn signal problems are due to a faulty turn signal switch. The turn signal switch is part of the combination switch found in the steering column and is mounted right behind the steering wheel. You may also notice that the wiper switch is not working either. That’s because the turn signal switch and wiper switch are combined.

To replace the combination switch, you will need to remove the steering wheel. This is a very straightforward procedure. Remember to disconnect the negative battery terminal.

Look at the part inside the turn signal/combination switch that often fails. You can’t replace the internal part. Therefore, the whole turn signal switch needs to be replaced.

Click here to check prices on new & used Mercedes turn signal switches on Amazon

Solution:

Replace the turn signal switch. You can replace it with a used turn signal switch; no programming is required. Ensure the new or used switch you install has the same part number as the existing one. To find the part number for your existing switch, call your Mercedes-Benz dealer parts department, provide them with your Mercedes-Benz’s VIN, and they will identify the compatible part numbers.

Once you have the part number for your turn signal switch, check the following listings to find a replacement turn signal switch for your Mercedes-Benz.

• Check Mercedes turn signal switch prices on Amazon

3. Turn Signals and Emergency Hazard Flasher Inoperable

Problem:

• None of the turn signals work. Left and right turn signals don’t work.

Cause:

1. Burned turn signal fuse.
2. Defective hazard light switch.

Solution:

1. Replace the fuse designated to protect the left and right turn signal fuses.
2. Replace the hazard light switch. For a temporary fix, try pressing the hazard light switch several times. This may unstick the hazard switch button and return your turn signals to normal operation.

4. Blown turn signal fuse

Problem:

• A blown turn signal fuse or turn signal fuse keeps on blowing.

Cause:

Short in the wires that provide 12 volts to the turn signal.

Solution:

You will need to locate the short and repair it. Check the wiring inside the headlight or tail light, as the insulation of the wires may melt over time, causing a short. We have seen this happen on several E and CLK class models. A good technician should be able to help you with this procedure if you get stuck.

Some of the locations where shorts can develop are the following:

• wiring harness
• Inside the headlight assembly
• Inside the tail light assembly
• mirror housing
• Where the door harness goes from the door to the body

You Fitted an LED Bulb and Now the Car Says It Is Out

This is the single most common reason a turn signal that worked perfectly stops working right after somebody changed the bulb, and it catches people out because the new bulb is not faulty at all.

You have three ways out of it:

• Go back to the correct filament bulb. Simplest, and the one that always works.
• Buy LEDs sold as CANbus ready or error free for your specific model, which build the extra load in so the module sees what it expects.
• Fit a load resistor in parallel with each LED so the circuit draws the current the module is looking for.

Check CANbus ready LED turn signal bulbs on Amazon

Frequently Asked Questions

My Mercedes turn signal stops working after driving for a while.

Tracking down intermittent turn signal problems can be challenging. Most shops and sometimes even dealerships may send you home with a repair order that says “can’t track customer complaint.” Often, when you take the car in, it isn’t acting up. All mechanics will have a hard time tracking down intermittent problems. They can’t fix a problem that they can’t duplicate. Our advice would be to find a shop with a scanner that reads the SAM modules, or get one yourself, because an intermittent fault that is not acting up right now still leaves its record in the module or take the car to the Mercedes-Benz dealer and have them complete a full system scan. Hopefully, one of the control units recorded the problem and stored a fault code. If there aren’t any stored fault codes, finding out what is causing your turn signal problem will be extremely difficult.

Can I disconnect or unplug the SAM unit?

No, you can’t. It controls multiple systems. The vehicle may not start.

The LED turn signal light stopped working; what should I do?

LED lights rarely fail. The first test you should perform is to disconnect the LED turn signal light and apply power to the LED bulb. Does the LED light turn on?

• If the LED doesn’t turn on, replace it.
• If the LED turn signal light turns on, the LED light is not the problem. Follow this troubleshooting guide to find out what is causing your turn signal problem.

What are the locations of the turn signal bulbs and sockets?

• E2e2: Right low beam
• E1e1: left high beam
• E1e3: left standing/parking
• E1e4: left front fog
• E1e5: left turning signal

We sell the YOUCANIC UCAN-II Pro. The function comparisons below come from each manufacturer’s own documentation so you can check them yourself.

What Scanner Can I Use to Diagnose the SAM Module?

The bulb, fuse, relay and voltage checks above are free or nearly free, and they catch most turn signal faults. Where a scanner earns its place is the SAM module itself. The turn signal outputs are driven by the SAM, and the SAM keeps its own fault memory including bulb monitoring faults that name the exact circuit. That is what tells you whether the module has deliberately shut an output down because it believes the bulb is dead, which is a completely different problem from a broken wire and looks identical from the socket.

Running those checks tells you what the bulb and the wiring are doing. It does not tell you what the module has decided. A YOUCANIC UCAN-II Pro reads the SAM and body modules, names the circuit that is flagged, and runs the active tests that command a lamp output directly, so you can see whether the SAM is sending current at all before you start pulling trim apart. It covers what Xentry covers apart from online VIN coding, with no subscription and no annual license.

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