Mercedes Relay - Vemo V30-71-0041

Product Information

A multi-purpose relay is an electrical switch that uses a small electrical current to control a larger current electrical circuit. The function of a relay is to activate various systems or functions that use a high electrical current without requiring high-current wiring directly running through the switchgear or ECU. The relay consists of a coil and a set of contacts. When a small current energizes the coil on the low current side, it creates a magnetic field that flips the switch back and forth, closing or opening the contacts and completing or breaking the circuit that powers the high-amperage device.

Multi-purpose relays are generalized relays that can run a number of different types of systems, such as fuel pumps, cooling fans, lighting, HVAC components, and windshield wipers just to name a few. This is why you will notice a multi-purpose relay may be listed for several different applications within a car, or the same application across multiple vehicles.

To diagnose a relay, you can energize the low current side using a basic 12v signal. You will hear the relay clicking. If the click is inconsistent or dulled, it might not be making a good contact. When it clicks, a multimeter should show continuity and near-zero resistance between the high-current contacts. If not, then the relay may be bad. Basic multi-purpose relays are very simple devices, so they don’t usually fail. However, if the relay has been subjected to extreme temperatures, or weather exposure, or is very old, never rule out a bad relay causing problems in your electrical system.

• System Failure: Several systems use multi-purpose relays to power them. When a relay goes bad, those systems will intermittently work or fail. A proper electrical diagnosis with a multimeter, or swapping the relay with a known good one is the best way to fix a failed relay.

About Vemo

The premium brand VEMO is known as a specialist in sensors and exhaust gas recirculation. Besides continuous product development in the field of EGR, VEMO is also a leading manufacturer of sensors, switches, relays and air suspension on the aftermarket. With our VEMO Expert Kits+, we help you carry out fast, cost-effective repairs and save you time and money!

The VEMO range includes high-quality products suitable for European vehicles such as VW, AUDI, BMW, MERCEDES-BENZ and PSA, as well as for those from Asian manufacturers such as TOYOTA, KIA and many more. The premium brand VEMO is characterized by its customers’ continuing trust and the benefits of extensive experience in the automotive industry.