W124/W201 hazard lights dead? Check turn signal relay A2018210247
Short answer: If the turn signals and hazard lights stay dead in the Mercedes W201, W124, W126 or W202, or if the wiper interval also fails, the cause is often the combined turn signal and wiper relay. First check bulbs, ground and fuse, then measure at the relay socket. If the defect is confirmed, replace the relay with part number A2018210247 – tested and in stock for 19,00 €.
Anyone searching for “A2018210247” usually already has the old relay in hand: the number is printed on the housing, the turn signals are dead, and the question is whether exactly this component is to blame and which replacement fits. This guide shows how to narrow down the fault properly before you spend money, and what to look out for with the part number. Because in the W201, W124, W126 and W202 model series there are several relays with a similar field of application – closely related is, for example, part number A2018210047, which we cover in a dedicated guide to turn signal relay A2018210047 .
Symptoms
| Symptom | Likely cause |
|---|---|
| Left and right turn signals not working, no clicking | Relay no longer switches – typical failure pattern |
| Hazard lights stay dark, turn signal stalk still works | Single circuit in the relay or contact problem at the socket |
| Turn signals fail only in warm weather or after a longer drive | Hairline cracks in solder joints inside the relay that open when warm |
| Wiper interval failed, constant speeds still work | Interval function of the combined relay affected |
| Not to be confused with: Relay clicks in rhythm, but lights stay dark | Bulbs, sockets or ground – not the relay |
| Not to be confused with: In addition, idle control, injection or other consumers fail | First check the overvoltage protection relay – see Check 7-pin OVP relay |
| Not to be confused with: Same fault pattern in the W140 | A separate control unit works there – see Check W140 turn signal unit |
Causes
A turn signal relay switches a load with every turn and every hazard-light phase – over decades this adds up to an enormous number of switching cycles. The contacts inside slowly burn away from the switching spark, and their contact resistance rises. Heat adds to this: every switching operation warms the connection pins slightly, the solder works, and after thirty years and more fine cracks form. Such faults almost always start sporadically.
The third factor is the environment. Long idle periods, moisture and temperature changes cause the plug contacts in the relay carrier to oxidize. Then it is not the relay itself that is defective but the connection to the socket – that is why cleaning the contacts always belongs in the diagnosis.
Testing it yourself
- Inspect bulbs and sockets. Check all turn signal lights including side markers and the indicator light. Blackened bulbs, loose sockets and corroded (green) bulb holders are the most common and cheapest cause.
- Measure the fuse. Remove the relevant fuse and measure it with a continuity tester – with old torpedo fuses, breaks are often not visible. Clean corroded holders down to bare metal.
- Read the part number and clean the contacts. Pull the relay, note the printed number and treat pins and socket with contact cleaner. Then reinsert firmly and test.
- Measure voltage and ground at the socket. If there is no system voltage with the ignition on, the fault is upstream – in the fuse, ignition positive or wiring harness. A new relay would then be the wrong investment.
- Swap test. If voltage and ground are present, insert a working relay with the same number. If turn signals, hazard lights and interval then work, the diagnosis is complete.
Solution
If the relay is confirmed as the cause, it is replaced – the relays are potted, and a repair is not worthwhile in practice. We supply the original Mercedes relay with part number A2018210247 (also written A 201 821 02 47), which is listed in the product data as a turn signal or wiper relay for W201, W124, W126 and W202. Every unit was tested before shipping and works. Installation is a simple plug connection. Important: if your old relay shows a different number, we will check the fit in advance free of charge.
Mercedes turn signal relay / wiper relay
Part number: A2018210247
Fits: W201 · W124 · W126 · W202 · Condition: tested, working
19,00 €
View productYou will find more tested relays in the category Mercedes relays & control units, the range for the E-Class at W124 and for the 190 at W201.
Compatible vehicles
| Model series | Note |
|---|---|
| W201 (190) | Fits according to product data. |
| W124 (E-Class) | Fits according to product data. |
| W126 (S-Class) | Fits according to product data. |
| W202 (C-Class) | Fits according to product data. |
| Other model series | Not covered – please inquire before ordering. |
The number on your old relay is always decisive. Model year and equipment can require different versions within a model series.
Turn signals dead? The matching relay is ready.
Original relay A2018210247 for W201, W124, W126 and W202 – 19,00 € in stock
View nowFAQ
How do I know that the turn signal relay A2018210247 is defective?
Typically, both turn signal sides and the hazard lights stay dead at the same time and the usual clicking is missing, even though bulbs and fuse are fine. The suspicion can only be confirmed reliably with a voltage measurement at the socket and a swap test with a working relay of the same number.
What is the difference between A2018210247 and A2018210047?
Both numbers are listed in our product data as turn signal or wiper relays for W201, W124, W126 and W202. Which version is installed in your car is printed on the housing of the old relay. Order the number printed there, or let us check the fit in advance using your VIN.
Can I replace the relay myself?
Yes. The relay is plugged in; replacement needs no special tools: pull off the old relay, check the socket contacts for corrosion, insert the new relay firmly and test all turn signal functions as well as the wiper interval. Switch off the ignition beforehand.
Why does the relay click but the turn signals don't light?
If the relay clicks in rhythm, it is being triggered and switching. If the lights stay dark anyway, the cause is usually downstream of the relay: bulbs, sockets, ground points or connectors. Replacing the relay generally does not help in this case.
How much does the turn signal relay A2018210247 cost and is it available?
The tested original relay with part number A2018210247 costs 19,00 € with us and is ready in stock. According to the product description it is tested and works; what is delivered is the scope of delivery as pictured.
KFZTeile-Thot is a specialist business for tested and refurbished Mercedes parts with our own test benches. Every part is personally tested before shipping, and over 1,000 positive eBay reviews show that this standard is appreciated. Unsure about the part number or want to discuss a fault pattern? Call us at +49 179 8991069 (Mon–Fri 8 am–6 pm) or use our contact form – we will check the fit using your VIN free of charge.