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Having a bit of an issue with a battery drain at the moment. When looking in the boot area, drivers side. I noticed 2 relays marked as 643. One of them was very warm. I'll probably just replace it anyway but does anyone know what these two relays do? Nothing in the handbook

A quick search of the relay and they are just normal open and close circuit relays. Very unlikely that changing them will cure your fault. You need to really find out the source of the trigger that is activating the relay. They seem to be 40amp relays so that's a large current user. Unplugging the relay completely will stop your current draw until you fix the problem and whilst it's unplugged go through all your electrics testing everything until something isn't working and that'll be your culprit. I'm guessing heated seat,heated rear screen or even main engine fans.

Ps I don't have an RS6 but I used to work on car elecs.

Eddie555 wrote:A quick search of the relay and they are just normal open and close circuit relays. Very unlikely that changing them will cure your fault. You need to really find out the source of the trigger that is activating the relay. They seem to be 40amp relays so that's a large current user. Unplugging the relay completely will stop your current draw until you fix the problem and whilst it's unplugged go through all your electrics testing everything until something isn't working and that'll be your culprit. I'm guessing heated seat,heated rear screen or even main engine fans.

Ps I don't have an RS6 but I used to work on car elecs.

Thanks for that, battery drain is only actually pulling 2.8A. It's just I noticed this relay was hotter than I would expect it to be. I literally ran engine for 4 minutes and shut off. Noticed abnormally high temp on relay. If I knew what these relays were for, hence the post, I'd have a bit more of a starting point. I may have to give in and send it into main dealers as I hate not having my car

Looking at Etka it's saying that the relay could be one of two things -

"Contact close relay, rear window" if it is the relay in position 1 or "Contact close relay, for vehicles with auxiliary heater" if it is the relay in position 3. There's also a Position 2 relay but there's no info on that one so it's difficult to know what it does, if it is fitted.

Here the page with the very limited info - It's Item 49 & position info is in the Notes column - http://www.realoem.me/Audi/RDW/RS6/2010 ... 937/937000

Thanks Ian. Much appreciated. I think I'll just remove it and see how I get on going by that info