Vantage dead on start button press up, Engine fuse box?

[Mish 80]

Hello, another month, another problem...

Got in car. Put keys in ignition.
Detached trickle charger while fuel pumps charged. A warning about no rear lights(one wasn't connected while drying out).

Foot on clutch and also fully down on the accelerator.(Trying to build oil pressure after 6weeks no usage). Red light on start button pressed it...
Everything went black, no interior lights, no red alarm blinking light, no central locking, no electric window, no window drop, no boot release. No sure if there a click or anything mechanical as had my noise cancelling headphones on.


Battery is 12.7v. Fitted Oct 2024.
Disconnected battery and left off 10mins, reconnected and repeated a few times. No change.
Pressed the Battery disconnected yellow button behind the drivers seat(BDS).

No fuses blown in the boot, engine or passenger side box.

Voltage is showing on both sides of the BDS.

Connected the Ctek to the battery directly, no change.
Connected Ctek to the engine connection points and dome lights and red light returned. Put keys in dash and it was really faint but it said 'HW P/N:
4G431 0849CB'
Seats move and windows make twitching noises on their own. Hazard light switch results in no external blinkers but the button blinks and the dome lights dim in sequence.

13.3v charging on battery terminals with the engine Ctek mounted to the engine.
Both sides of the BDS have+ voltage with the battery attached. So it's not the BDS.

Boot fuse box is getting 14.1v when charger attached. 1.92v when no charger connected and no key.
No fuses seem to have voltage in the boot or engine bay.


Engine bay, all fuses are okay using a MM. No voltage on any when the ignition is off. Including the 60amp and the 40amp that sits separately nearby under its own cover.

I'm worried about low voltages effecting the other electronics so have not done much testing with the ignition key in.

At this stage I think it's the engine fuse box has completely failed when under heavy starting load. How do I test this theory? Under neath is there a good feed input to test that it's getting 12-14v.
I can't seem to see much info on the relays and what they do.

Ideas?

Edited by Mish 80 on Sunday 30th March 15:48

[LTP]

Try putting a decent-sized jump lead between one of the underbonnet body castings and somewhere on the engine block. Make sure you have good connections, then try again.

[Vsix and Vtec]

It could be the main fuse. They don't go very often, but when they do, it's the last place anyone looks.

[Mish 80]

Vsix and Vtec said:

It could be the main fuse. They don't go very often, but when they do, it's the last place anyone looks.

Where is this beast in the Vantage??

It's Ford transit part apparently.

Feels like a fuse as it was sudden at the point of high load, cranking the engine

[kabman]

That doesn't look like a fuse. The diagram on it suggests a flip-flop relay.

[Mish 80]

So I traced the live power from the battery under the carpet to a bolt roughly where your heels are in the drivers seat. It is getting 12v+. Smaller guage wire appears go to the boot fuse box, which has 12v.

I was looking for a relay or fuse or anything near the BDS, couldn't find anything. Rang a dealer, said my car, an early 2005 example might have some differences to 06+ cars but I should still have some basic electrics working. I did see a thread about a DBS with that 190amp fomoco relay, but can't see it in my car near the battery, could it be further into the engine bay?

Next I'll see if the live from the interior by the pedals, actually makes it further into the engine bay, see if I can find the exterior exit point of this behind the wheel arch.
A side from the battery jump point in the engine bay, where else should I find a permanent 12v?

Anything to check in the CEM cabin fuse box?

[TR-Spider]

Did you try to jump start?

[Mish 80]

Thanks for the help!

Sooo.

I checked the 12v feed through cabin, under the pedals and the live bolts under the wheel arch and then the engine bay jump mount and it's showing 12+.

I then connected a battery to the engine bay battery points in addition with car battery also connected and it was came alive! (No need to worry about CEMs, trackers etc)

I then connected just the negative jump lead from the engine block to the negative terminal on the interior battery. And it came alive again...

So, a bad earth...
Still confused why it happened on the literal engine start.

So where do I go from here? Engine block earth?

[LTP]

Mish 80 said:

Thanks for the help!

Sooo.

I checked the 12v feed through cabin, under the pedals and the live bolts under the wheel arch and then the engine bay jump mount and it's showing 12+.

I then connected a battery to the engine bay battery points in addition with car battery also connected and it was came alive! (No need to worry about CEMs, trackers etc)

I then connected just the negative jump lead from the engine block to the negative terminal on the interior battery. And it came alive again...

So, a bad earth...
Still confused why it happened on the literal engine start.

So where do I go from here? Engine block earth?

This is why I suggested you put a jump lead between the engine block and one of the underbonnet castings earlier in the thread.

The engine earth on the VH cars is underneath, between the torque tube and the body, see pic



I have no idea why Scuderia shows two - as far as I know there's only one, and both parts in the diagram are showing the same part number. You could find that the braid is fraying and may need replacing, but more likely all you'll need to do is to undo the bolts from the rivnuts, give everything a damn good clean with some wet-or-dry and a wire brush, and refit. Then coat the joint with a waterproof grease of some sort to keep everything dry.

The reason it happened is simple - good old Ohm's Law. When you're measuring voltage you're drawing virtually no current, so even with a high-resistance, corroded joint you'll see (almost) battery voltage. Try to crank and pull 100A through that high-resistance connection and the voltage drops like a stone; which is why everything goes black.

Before you climb underneath it'd be worth checking all of the connections to the battery - not only the actual terminal connections, but also the lead to earth from the negative terminal where it bolts to the body, because that could give the same symptoms if it's a poor connection. Connecting a second battery directly to the engine avoids your main battery having to supply massive amounts of current, so it can keep the car alive, even through the high-resistance connection

[Percy Penguin]

When I had a similar issue last year, I seem to remember that the engine earth cables are actually at the back of the car on the gearbox, one on each side, rather than on the engine itself.

Mine were found to be fine, and the issue was (I was told) the positive connector on the body behind the driver's side wheel liner - i.e. the other side of where the pedals are.

I'm not sure how that gives an earth fault, but might be worth checking out - apparently mine was very crusty, and once cleaned up fixed the fault.

[Mish 80]

Thanks both!

I checked the negative stud and that seems pretty solid but brushed it anyway.

Very interestingly I jacked the car up on one corner and power was restored...

So the ground is via gearbox...well that has been out recently.

Is it reachable with just a trolly jack on the drive? or does the mid section exhaust, then sheilds needs removing?

A little scared to drive it though if it's that sensitive

Edited by Mish 80 on Saturday 5th April 18:04

[Percy Penguin]

So, from memory, on my 2006 V8V the R/H one is easy enough to see if you can get under the car but the L/H one is a bit further forward and not so obvious (I missed it, thinking there was only one earth). However, once you know it's there you'll see it.

[LTP]

Mish 80 said:

Thanks both!

I checked the negative stud and that seems pretty solid but brushed it anyway.

Very interestingly I jacked the car up on one corner and power was restored...

So the ground is via gearbox...well that has been out recently.

Is it reachable with just a trolly jack on the drive? or does the mid section exhaust, then sheilds needs removing?

A little scared to drive it though if it's that sensitive

Edited by Mish 80 on Saturday 5th April 18:04

I've not done this, but I'd always recommend ramps rather than a trolley jack, if you have them. The Vantage rear departure angle is pretty big, so you should (?) be able to get ramps to the rear tyres, then drive up - clutch torture accepted! If you get it up (oooh, eerr, missus!)
then you can crawl around underneath to your heart's content.

@Percy - so the Vantage does have two earth straps? Interesting - I didn't know that, so that's filed away for future reference. It also explains why Scuderia lists two identical part numbers in different physical configurations on one car.

[Percy Penguin]

LTP said:

@Percy - so the Vantage does have two earth straps? Interesting - I didn't know that, so that's filed away for future reference. It also explains why Scuderia lists two identical part numbers in different physical configurations on one car.

Yes, mine certainly does.

[Mish 80]

To be clear, I pressed the start button and it blacked out and stayed permanently blacked out.
That is the odd part to me. Perhaps the spark load did something. When lifting the car it did restore power so the twisting force or the tilt re-aligned it.



I've put together some photos and can see there is two grounds on the grazianio trans in some examples. One around 2pm if facing the trans from the engine, another on the shorter engine mount on the opposite side.

[Mish 80]

Vsix and Vtec said:

It could be the main fuse. They don't go very often, but when they do, it's the last place anyone looks.

So I've since found that is a relay just below the battery and is also known as the battery disconnect switch. I have inspected it and mine encased with no markings but the grey cable is the same. I can assume they are the same on other AMs.
They are prone to fail. To trouble shoot that you check that you have 12v on both bolts either side of the black box with the yellow button that have red cables connected top and bottom.