Fuse to Ecu keeps blowing

4.2 V8 40v biturbo - 450 bhp
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G pat
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Fuse to Ecu keeps blowing

Post by G pat » Mon Feb 29, 2016 10:10 pm

Evening all. Does anyone have any pointers as to why the 30amp fuse to the Ecu keeps blowing ?
It's happened twice in the last 3 or 4 weeks, big problem as the car just dies...
No damp carpets or foot wells, no steamy windows etc.
Thanks.

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Re: Fuse to Ecu keeps blowing

Post by Nobby » Mon Feb 29, 2016 10:27 pm

The one in the scuttle?
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Re: Fuse to Ecu keeps blowing

Post by G pat » Mon Feb 29, 2016 11:10 pm

Oh sorry no, the one on the main fuse board. I didn't know about the other one, good to know.

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Re: Fuse to Ecu keeps blowing

Post by Nobby » Tue Mar 01, 2016 8:52 am

Have you checked the scuttle panel for water? Mine was almost full of water (blocked drain hole) and some of the main electrics where submerged. Luckily no fuses went.
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Re: Fuse to Ecu keeps blowing

Post by Shoppinit » Tue Mar 01, 2016 8:55 am

Which number fuse?
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Re: Fuse to Ecu keeps blowing

Post by G pat » Tue Mar 01, 2016 10:40 am

Fuse number 29, I haven't hap a chance to check the scuttle yet

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Re: Fuse to Ecu keeps blowing

Post by Shoppinit » Tue Mar 01, 2016 10:50 am

Lots of stuff coming off that fuse. It could be a short somewhere, or a fault in one of the following:

Ignition coils
Engine mounts
Camshaft timing valves

Not easy to determine which. You got any logged fault codes? Might help narrow it down.

My gut says a dodgy ignition coil.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuse to Ecu keeps blowing

Post by G pat » Tue Mar 01, 2016 5:45 pm

Thanks for the help so far :thumbs:
I haven't had chance to check for codes yet today, but I do get the usual engine mount one.
I'll do a scan later today or tomorrow, although I don't have VCDS so how would I check the coil packs if no misfire shows up which it didn't the last time number 29 showed me the middle finger?
Cheese.

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Re: Fuse to Ecu keeps blowing

Post by Shoppinit » Tue Mar 01, 2016 6:23 pm

Problem is that fuse 29 takes the ECU out before it can store a fault, possibly. If you've got a faulty mount then I'd start by sorting that since it's on fuse 29 also. Maybe just unplug it for a while to see if that stops the fuse blowing.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuse to Ecu keeps blowing

Post by G pat » Wed Mar 02, 2016 12:32 pm

The matter has been taken out of my hands now as the car left me stranded this morning, grrr, has anyone ever tried pushing one of these things!.
It blew the fuse every time the engine was started, four times, I had to pinch them from non essential items.
So just waiting for the car to be recovered by a local garage who I think might have difficulty in finding the cause.....
We shall see..
:audibash:

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Re: Fuse to Ecu keeps blowing

Post by Shoppinit » Wed Mar 02, 2016 12:43 pm

It's good that it's now doing it consistently. Will make trouble shooting much easier.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuse to Ecu keeps blowing

Post by G pat » Wed Mar 02, 2016 1:19 pm

Agreed, I was kind of glad to be honest as it's the sort of problem you never know for sure if you've sorted or not.
Thanks for the help thus far although there may be a few more questions to come if the garage draws a blank.

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Re: Fuse to Ecu keeps blowing

Post by G pat » Mon Mar 07, 2016 9:47 pm

Got the car back today, the problem turned out to be the wiring loom, not sure which part, had been tampered with and attached with cable ties allowing movement causing the wiring to rub through the covering and shorting to the bodywork.
Only cost a very reasonable £170 including recovery, so not too unhappy, could have been much worse.
Mind you spending the last couple of days driving around in the old Quattro ur was nice.
Thanks for the help and suggestions gents.

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Re: Fuse to Ecu keeps blowing

Post by mavada » Mon Mar 07, 2016 9:57 pm

Nice you got it sorted :thumbs:
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Re: Fuse to Ecu keeps blowing

Post by Shoppinit » Mon Mar 07, 2016 10:13 pm

Cool. Glad it was relatively painless. :thumbs:

How about a gratuitous UrCuntro pic? Any seconders?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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