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Discussion Starter #1
A few times the car has said ESP Fault & Brakes when starting, but started anyway, Now it won't start at all and I get those 2 messages. It is a manual V8 BTW

I have 12.16V on the battery according to my multimeter which should turn it over - the car hasn't been used for a week or so but that's usually OK. Got a good run 6 days ago - 2x 40 minute motorway / highway runs - I don't think it is the battery

I saw on here someone suffered this & it was the 'main supply relay' that needed replacing - I am assuming that is on the main relay board in the assenger footwell

Can anyone tell me which relay it is & what type I need to swap it for - as something to try before getting it trailered away :(

I am hoping it isn't a bad ECU...
 

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Discussion Starter #3
IMG_3639.jpg

The recovery guy got this off diagnostics
He advised swapping main relay & going from there but he didn't have the correct type of relay on his van to test so I can try tomorrow morning
I hope this rules out the actual ECU being faulty as that is expensive
 

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Discussion Starter #4



The recovery guy got this off diagnostics
He advised swapping main relay & going from there but he didn't have the correct type of relay on his van to test so I can try tomorrow morning
I hope this rules out the actual ECU being faulty as that is expensive
 

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Discussion Starter #5



The recovery guy got this off diagnostics
He advised swapping main relay & going from there but he didn't have the correct type of relay on his van to test so I can try tomorrow morning
I hope this rules out the actual ECU being faulty as that is expensive
 

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I recently had a similar situation with symptoms and diagnostic readings like these, which turned out to be an earth bonding wire where the nut had vibrated loose causing arcing. This plastic unit holds relays and is located behind the rear shelf panel.

1BD40323-A00E-43C6-B876-B3F382B740B1.jpg

The replacement relay cradle was £20 plus an hours labour to fit.
 

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I recently had a similar situation with symptoms and diagnostic readings like these, which turned out to be an earth bonding wire where the nut had vibrated loose causing arcing. This plastic unit holds relays and is located behind the rear shelf panel.

View attachment 235390

The replacement relay cradle was £20 plus an hours labour to fit.
An interesting observation for potential future problems,
 

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Discussion Starter #8
It was all OK this morning after refitting the old relay. I bought a new relay anyway and replaced it due to low price & ease.
Car is in the shop now for a new front lid
When I get it back I'll get the rear bench off and check out that earthing point looks like an easy fix if that's it
 

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Discussion Starter #9
So this problem again... I think I have identified it as I can now replicate the fault at will but it is a weird one

If I remove the fuel pump relay, the very top of 2 of the pins (close to the relay, not the tips), are a little discoloured & it has a very slight slight electrical burning whiff about it. With this relay removed, the fault (ESP Fault & Brakes, car not starting) occurs every time I turn ignition on.

But now that I have ferreted about with it, the car is perfectly fine anyway, as though there was a loose connection or something

I have tried swapping it with the other relay on the same tray & it seems to be working perfectly with both relays.

So either the relay is on its way out & the discoloration on the pin and slight smell point to this - or there is a fault in the wiring to or around the relay - I've had a really good look and can't see anything though.

All I can think of is to replace both relays (they are a very common VAG part for about $8 each) and see how it goes from there as I want to avoid spending on hours of diagnostics if possible and I have use of another car.

Any thoughts appreciated!
 

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Discussion Starter #10
Singed relay terminals - this isn't normal is it!?



Relay board - if I remove the one on the left completely the fault occurs 100% of the time.
BEEP - ESP fault
BEEP BEEP BEEP - Brakes

If I replace the relay the fault completely disappears

It's the one on the left. Removing the one on the right or swapping them makes no difference



And every now and again I get the fault with the relay in place
 

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Difficult one. Clearly there shouldn't be any signs of discolouration to the relay pins so something is amiss. If it were me, I would replace the 'faulty' relay with new and monitor it regularly. If it shows the slightest signs of discolouring, you may possibly have a relay carrier or wiring fault.
 

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Discussion Starter #12
Thanks... it's not a coincidence is it that the relay pins are burned and then when I remove it I get the intermittent fault 100% of the time
 

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Discussion Starter #14
Ricky just said to swap the relay, keep an eye on it, if the scorching comes back then we know which circuit has got high resistance on, making the relay overheat. I'm guessing it is an issue with the circuit as it's happened to 2 relays on that board. Can't see any evidence of a bad earth anywhere but I guess it could be anywhere on the circuit
 
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