Hi I have an R470 Scania with a fault on the wiring ,First thing in a morning or after it has been stood for a while everything is ok , but run it for an hour so and the horn doesn’t work ,spots ,front fogs and rear fogs cotro; does work ,neither does the washers , Stop turn the ignition off and the everything is fine again for a while thought it might be the aux light switch , changed that still the same , Could any one shed some light this for me
Someone else might know more but I have a feeling with those symptoms an ECU may be stuffed.
Yep, stinks of a cold ECU fault. Mine is the same, throws up one dashboard fault after another first thing in the morning, if I let it warm up, then turn it off and on again it will behave perfectly for the rest of the day.
ecu all day long, been there and got the t/shirt 
I was hoping it wasn’t but does throw some dash faults up ,
Bad copper track in main fuse box/distribution board or a bad cab earth.
Horn, and fog lights, sounds like it is the loom which runs next to the O/S front cab airbag, split open the protective ■■■■■■, and check the wires, it is a common fault, water ingress and the constant flexing of the loom in that area causes wires to split, and rust away.
jimmy2loads:
Horn, and fog lights, sounds like it is the loom which runs next to the O/S front cab airbag, split open the protective ■■■■■■, and check the wires, it is a common fault, water ingress and the constant flexing of the loom in that area causes wires to split, and rust away.
This is correct ,I’ve seen lots of these .
I hope it is but this wouldn’t cure by switching it off and on again unless somehow by being stationary it’s allowing the connection to be made again.
Washers and horn are not ECU controlled as they have to work without going through protocol
(asking other ECUs if they have priority)They are fed constant live and the switch just earths them.
Pointless pressing the horn or washers and having a second delay before it operates.
Own Account Driver:
I hope it is but this wouldn’t cure by switching it off and on again unless somehow by being stationary it’s allowing the connection to be made again.
I would check it, just to rule it out, but i am guessing i will correct in my diagnosis. 
Dan Punchard:
jimmy2loads:
Horn, and fog lights, sounds like it is the loom which runs next to the O/S front cab airbag, split open the protective ■■■■■■, and check the wires, it is a common fault, water ingress and the constant flexing of the loom in that area causes wires to split, and rust away.This is correct ,I’ve seen lots of these .
Its has happened on the first three Scania’s i’ve owned Dan, touch wood my current one is ok, for now, lol.
Right we have an update , My mechanic has put it on the computer and found 10 or 11 faults he has reset it and i am running for a day and plugging again see what brings up ,