What is the relevance of a part called a RELAY on a diesel Volkswagen Lupo?

Question

My son-in-law's car keeps cutting out. He has replaced all the glow plugs and it has been suggested it is the RELAY. He asked me and I don't know what a relay in this context is. Perhaps someone could advise.

Answer 1

there are lots of relays in a car's system. if you have a relay/glow plug problem, there will be a glow plug mil on the dash while driving. it may flash as well. this lite is a curly line like a pig's tail. sorry.. best description i could come up with on a early morn.. heehee. you dont say what model /year /engine you have, so , once again, we all have to guess here.there will also be a dtc in the ecm. alot of bridges go bad. the bridge is the thick black harness that goes to each glow plug. replaced many of these. if it's a tdi, which i suspect it is,(the other engine would be a pd engine, both being diesels) the diesel pump may be bad. it will cause of a big variety of driveability issues, and 99% of all diesel issues are fuel/ fuel filter/ tank pump/ diesel pump related. this is something for an EXPERIENCED tech to handle. not a general shop.

Answer 2

A relay is a device that allows a small current to switch a much larger current. There will be quite a number of relays in a car's electrical system, and they will all operate on a similar principle. I would suggest that the cutting out problem on the car isn't to do with the heater plugs, or the associated relay, as those parts of the car are only in use from a cold start. There are, however, numerous other relays that may cause the problem, and a whole host of other devices, both electrical and mechanical, that could also cause the problem. I would suggest a diagnostic check with a friendly and experienced auto technician.



For Roary 69, 'master mechanic'... the voltage doesn't vary, the current does which is why a relay is used. You lecture, and you tell your students that the voltage changes?? No wonder all the grease monkeys are ignorant these days.

Answer 3

A relay is a device that controls a lot of power with a little power. In most cars there are several relays. When you turn something on you use a little bit of power...1 to 20 amps, to turn on a relay that will transmit the needed power, say 80 to 100 amps, to the device the relay controls.

Glow plugs heat up the cylinders in a diesel engine for easier starting. I doubt that they, or the relay that controls them, would cause an engine to "cut out'

A faulty relay that controls how the engine performs while running would cause one to "cut out".

Security? Fuel? Injectors? Fuel pump?

Answer 4

A relay is a heavy duty switch which uses a light voltage and current to switch on and off a heavier voltage and current, which would burn out other switches, in a car they usually are black or red (sometimes other colours depending on the manufacturer) and are usually located in the engine compartment, they have betweeen 3 -6 metal terminals and they have numbers on the terminals which can be followed in a wiring diagram, if you live in the uk the best thing is to buy a haynes manual which will give you the location of the relays and then change it, dont go to halfords (they are mega expensive) your local parts place should have them in stock

Answer 5

A relay is an electrical switch that opens and closes under control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered, in a broad sense, to be a form of electrical amplifier.

Answer 6

The relay sends electricity to the glow plugs.

Answer 7

Controls the feed to the glow plugs, 'cos it can handle a heavy current while the ignition switch can't. The ignition switch triggers the relay to do the heavy work.