General No power to ecu or double relay 2004 jtd

[Bambo]

Anybody know the wiring diagram from ignition to double relay then to ecu. When I turn on the ignition the relays not getting power nether is ecu. Relay is fine. Engine turns but no start.
I've opened up the relay and there are two coils inside if I make contact with the one on the left side the ecu powers up and will start but if I let it go ecu turns off and engine cuts out. No fault codes on ecu. Also when I turn on ignition the temp gauge flicks hot to cold

 

[Bambo]

Any ideas still can't work it out

 

[bigdong]

I had this same problem a few weeks ago, The code reader could not find the ecu to give any codes. (if your code reader can find the ecu and shows no faults then this is not the problem. If you cannot find the ecu with the code reader then it probably is). I had to replace the ecu, got one off ebay for £275. If you need to do this make sure of the following. The part No on the new ecu is the same as the old one, The kit you buy is complete as follows-- ECU, SMALL BLACK BOX, BLACK SHROUD FOR IGNITION SWITCH, IGNITION KEY. The whole job takes about half an hour as it is all plug and play but you must replace the whole lot as it is all married together. The shroud with the new key I just taped it up inside the dash but the key that comes with the kit MUST be secured inside the the shroud or the van will not start. After fitting I just turned key and bingo no further problems. Beware if you do this, replacing the ecu on its own will not work!! Make sure you get the whole kit.

 

[Bambo]

But if I lift the contact on the double relay I can then read the ecu but it comes up with no fault codes.

 

[bigdong]

Unplug the ecu and open it up. Have a look at the circut board, it should be as clean and shiney as the day it was born. On my one there was clearly signs of heating/burning on the board.