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Thread: RS6 down for the count.... Main Fuse block corrosion

  1. #1
    Registered User Kgnast's Avatar
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    RS6 down for the count.... Main Fuse block corrosion

    The car was being driven, coasting to red light. It shuts down and has ZERO power to anything. I mean ZERO. Bad thoughts are going through my mind and my wallet went and hid from me. So I was relieved to open up the cowl, and pull out the fuse block to find it totally corroded and the main power lead being totally disconnected from it. This is on the 150amp side of the two blocks.

    The drain was jammed up with debris and pine needles, etc which led to the corrosion. Anyway, could someone point me in the right direction for the fuse#/part# for the 150amp? Also, that block that it is mounted in? The mount and hardware are totally corroded too. It would be great to hear from someone who has had to replace that 150amp, the block, and the hardware, regarding part #'s, etc...... Thanks in advance.

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    Can you post a picture of where this fuse is ? I'd like to check mine out and see if the drain is in need of some servicing.

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    Registered User Kgnast's Avatar
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    I'll take some pics and post em up. For reference, its under the coolant reservoir. It's the only thing down under the coolant reservoir (to the right of the cabin filter located under the windshield on the passenger side of the car). Right smack in the middle of what would be the "bottom" of that area is a drain hole. Mine was completely jammed up with crud. If you have any water on the bottom area, this is what causes the wires to the main fuses to crap out.

    I'm shit out of luck though. The nuts are completely seized with rust. And the bolt head on the back is encased in plastic - it strips from this encasing easily. I still can't get the nut off the bolt using a 13mm crescent wrench on the nut and a 13mm socket on the bolt head on the other side.

    Ughhhh... This should be a 5 minute fix flat out.

  4. #4
    Registered User Kgnast's Avatar
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    Ok, the parts are "interlocking", meaning there are two blocks, one for the 200amp and one for the 150amp. Part numbers are 4B3 937 505 C and 4B3 937 505 D, C is the upper which holds the 200amp, D is the bottom which holds the 150amp.

    My car had both units with VW/Audi logos and the part numbers. They are both from MEGA but have the Brand logo on them. The 200 and the 150 amp fuses are from MEGA as well.

    I have order two new blocks and new fuses, I am replacing all the corroded shit, putting new terminal lugs on the wiring, and that should clear things up proper. I no doubt saved a truckload of cashflow from this, and not having to drop battery and alternator cash. Whew. Both fuse holders 4B3 937 505C and D, are $42 total at my local Audi dealership connect.

    Anyway, I hope this helps others who find themselves with ZERO power to anything in an instant... Check the firewall main fuses first!!!!!!! AND clear out those cowl drains!!!!!! (dead smack in the middle of the cowl pan, literally middle of the car).

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