Hi
I'm posting this on behalf of my son and wonder if anyone can help us please?
We have a 2005 JCW R53 which has been fine until yesterday when it completely refused to start.
All the normal ignition lights etc illuminate and the engine turns over but will not fire.
It feels like fuel starvation but we have been unable to trace any faults. Even though we hooked it up to a mate's Snap-On Ethos diagnostic tool, it was unable to establish a connection to the ECU, even though it would read the ABS unit.
We eventually checked ALL the fuses and discovered that Fuse 1 (5amp) in the engine bay had blown.
Unfortunately every time we replace it, it continues to blow.
Can anyone shed any light on this or point us in the right direction to obtain a cure?
Thanks in advance
Tel

Hi

F01 in the engine bay is for the ECM (DME) memory so you are looking in the right place.
I would disconnect the small plug on the DME (X60004) that's the one right at the back.
The plug has two lugs on it under the loom that comes into it, push it towards the bulk head the plug should start to lift up the more you push the lugs the higher it should lift till you can lift it off.
If you put a fuse back in F01 and turn the ignition on with it unplugged it should do one of two things
1 if the fuse blows you have a short in the wire belween the fuse and the plug you will need to find that it's a red wire with white line on it going to pin 40 of that plug
2 it does nothing which could mean your DME has a short in it

When you get the plug off you may find it is has corrosion on the pins so have a good look it might be worth pulling the other plug off and take the DME out just to make shore it's not corroded as well

Also with the ignition on, plug X60004 you should have no power on pins 33,34.
and on plug X6000 larger plug of the two pins 61,62,80 and 81 should have no power these are earths so check to ground as well as for power.

Also check F34 in the fuse box in the car passengers foot well this is the on off signal to DME
Hope this is a start hope it works out

Thanks for the pointer.
I removed the small ECU plug and the fuse blew as soon as it touched the contacts and without the ignition on.
I also removed the larger ECU lug and the fuse still blew.
So the good news would appear to be that the ECU is OK.
The bad news is trying to trace the wire to find the fault :rolleyes:
Firstly I've disconnected the battery in the boot.
Then removed the securing bolts to the fuse holder and the main 12v feed.
There is very little room to see what is going on under there and it's difficult to see where the sire heads off to.
Is there a schematic diagram of the wiring anywhere that may give us more clues?

Hi

i don't know if you have done it but remove the airbox it will give you just that little extra movement. your going to have to remove it any way to trace the wiring.
the wiring diagrams are very basic pin to pin and plug to plug stuff no routing.
i have attached some diagrams for you but it will not give you much info.

but before you dismantle the car lets try this first
at the front of that fuse box as you look down on it as it would normally be in the car, there is a connector X4013 disconnect it. you will see in pin 6 forward right hand pin location thats as you look at it, there is a red wire with a white strip thats the power wire to the DME to plug X60004 pin 40.
do this check first to rule out fuse box make shore everything is connected and safe.
make shore the plug X4013 at the front of fuse box is not connected put a fuse in turn on ignition and see if it blows.
if it blows you need to look at the fuse box and relays incase there is a short internally.

if it does not you need to basically start to trace the wire, i would put a multi meter on X4013 pin 6 and go to ground and then X60004 pin 40 see it it is shorting to ground.
if it is i would have a good look around where the wires come out of X4013 and run down past the engine/gearbox mount.
if you have to start to trace the wire damage start at the DME plug end and un wrap the loom and trace the wire as you go. just run a rings of tape around the loom as you go to keep it in place or it will be a nightmare to get back right.
the trouble is if you have one damaged wire there will be at least one more thats the way it goes unless your very lucky.
when you repair the wire make shore it is done correctly or it will lead to more problems.