Mercedes atego 815 2006 having problems with constant power to ignition and starting issues

Clarky39

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Mercedes atego 815 2006
Hi guys I’ve recently brought a Mercedes atego 815 sleeper cab hiab lorry all has been well until I was in the garage one night and out of the blue all the relays and modules randomly powered up. The lorry was parked on the drive locked no keys near by. It’s does this when the keys are put into the ignition and turned to the third click usually but now all of a sudden since it has done this the dash is constantly live as if the keys are already in the ignition and turned to the third click before starting. Upon finding this fault mr code 9964 and 9963 were present on the dash and charge battery fault. I charged the batterys and tried to start it and it just winds over and over no start, if I pull the flasher stalk the power is cut to the dash with the keys out the ignition like it should be and the minute I let go it returns to being permanently live again. If I pull the flasher stalk prior to turning the key in the ignition the dash powers down aswell as all the relays and modules if I turn the key while holding the flash on the relays power up on the third turn of the key and the lorry fires straight up but the minute you turn it off with the key and take the key out the ignition it stays running until you pull the flasher stalk again to cut the power.
At first I assumed it was a ignition fault I have disconnected this out of the equation and it makes no difference dash is still permanently live with everything constantly powered up, ive also disconnected the stalks no different, I also thought maybe it’s a earthing fault and it’s pulling a earth from the headlights when I pull the flasher stalk so I ran a direct earth from the battery to the cab no different. I have to disconnect the battery to cut all power and the minute I put the terminals back on the relays and modules power straight back up. If I put the left or right indicator on with the keys out the dash goes on of on of on of aswell as the modules and relays clicking on and off really fast
I’ve had it plugged in on Delphi diagnostics and nothing showed at fault, forgot to mention if I pull the flasher stalk the mr code fault disappears ive looked into the mr fault code key transponder fault but all must be well as it starts and fault code goes away upon pulling the flasher
No aftermarket immobiliser or alarm fitted
And no additional wires are connected to the battery just the original battery terminals, only aftermarket part fitted to the lorry is a 12v dropper next to the fuse box for the radio. I’m stressed and confused and lost for ideas any help and advice is much appreciated D24E42A4-FF97-4146-AD23-7BE965EF5EC2.jpeg
 

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clarkmichigan55b

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Mercedes 208D T1 van 1989
Hello,

I just looked up on an old thread on this forum of the same vehicle it may be of help.
also have you checked for any chafed wires etc.

 
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Clarky39

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Hello,

I just looked up on an old thread on this forum of the same vehicle it may be of help.
also have you checked for any chafed wires etc.

Thanks mate I’ve been going through the wiring loom that runs under the sump up to the starter motor thismorning and I’ve found water inside the plastic conduit were the loom is ive drained it and dried it all out and found a corroded red wire and a yellow shorting across each other, I have repaired these and everything is now back to normal thanks for the help
 

mattkh

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A160 W168 1999 1.6
Well done.
Any idea how the water got in there..?
 
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Clarky39

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The plastic conduit had a split in it further up and several of the wires had gone brittle and was causing it to short across
 


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