DME relay

[944 man]

Im relatively sure yes. Without intending to sound facetious, it is called 'DME relay', which certainly supports the argument that the relay provides power to the Bosch DME (Digital Motor Electronics / ECU). In earlier models it was referred to as the fuel pump relay, although the part is common and I believe that the function is the same (one internal relay for the DME and one for the fuel pump).

 

[barks944]

You are probably right. The way its wired is just a bit weird. I think then that the First coil provides the positive to the DME and the second coil. This means that the DME grounds the second coil to power the fuel pump.

Here is a well drawn schematic of the DME relay.

http://picasaweb.google.co.uk/tomspics1234/Pictures02#5317083618327607954

The only thing I cant quite explain is why the DME has 3 connections to the relay.

 

[berg944]

Could be a fuel shut off system in case of a crash?

I don't know what the sensor would be, Try putting your car on its roof[]

Mike[:'(]

 

[elvis]

One coil powers the DME and coil. This is switched by the ignition switch.

The other powers the fuel pump. The fuel pump coil is switched by the DME based on whether or not it sees engine rotation from the crank sensor (this is the 'crash sensor': if the engine stops so does the fuel pump)

Not that I spend all my time linking to Clarks garage, but:
http://www.clarks-garage.com/shop-manual/fuel-05.htm

I once spent three days trying to get the ^%$£ thing started after doing something fairly simple, turned out I had a duff DME relay AND I'd disturbed the crank sensor so even when I'd managed to get power to the DME, it still didn't think the engine was turning hence no fuel []

 

[barks944]

Nice one elvis.

 

[ukmastiff]

http://www.clarks-garage.com/pdf-manual/fuel-05.pdf

The above will tell you how to quickly and easily prove or discount that particular problem. If you can use a meter your in !

Regards Mas

 

[neilo]

Mine was about £25 all in (VAT and postage) from Porsche Silverstone a couple of months ago.

 

[sawood12]

Why did you purchase one from Porscheshop? They're cheaper from the OPC.

Anyway, you'd use it if you have starting problems that may be due to starvation of fuel and it goes in the fusebox.

 

[Northern924]

^^ What Scott says pretty much ^^

Depending on the year of your car its either under the glove box above the fuses (pre 85/5) or in by the fuses under the bonnet on a later car.
DME relay controls the supply of fuel and works in conjunction with the ECU, you basically end up stranded unable to start the car when they fail.

My Spare at the moment is from a Nova GTE, same DME replay [8D]

 

[dave364634]

the dme is a common fault.

make a 'thing' out of wire and spade connections, that connects the big three together.

if that sorts your problem it's new relay time.

 

[spooks]

Thanks Dave,

 

[Richair]

For a similar price to the OEM one you could buy a solid-state one from the US and never have to worry about it again... http://www.ftech9.com/new-products/bzmf0lleggf3cio89y8pyf3n9rf4hg

I'm not sure I'd trust a cheap aftermarket one personally.

 

[Craigybaby]

Cheers rich, that looks interesting, have you got one? I note it says fitment in a few minutes...is it just pull out the old one and plug in the new one?

 

[Eldavo]

I have one (as do 2 others as I got 3 whilst in the states a month ago). It's a straight swap, takes 10 seconds - I got the pump-prime version. Not sure that they ship internationally though.

 

[T911UK]

They dont ship, which is a shame because it looks like a great product!

OEM relays are fine, make sure you buy the correct OEM version though, made in Germany, on ebay for £22 delivered!

 

[Craigybaby]

Cheers, placed an order with you

 

[Craigybaby]

double post

 

[Craigybaby]

Received today....super speedy many thanks

 

[944 man]

I have one! Priming type too. Of course, its sat here on my desk - not in my car...

 

[Eldavo]

I'm more impressed that you've picked it up from your brother's so soon!