My 05 Scania R420 has horn and headlights problems. The horn stops working after the truck has been driven for 30 - 40 miles. Full beam on the headlights stops functioning. I have very little knowledge about truck electrics. Any ideas will be appreciated.
AMX:
My 05 Scania R420 has horn and headlights problems. The horn stops working after the truck has been driven for 30 - 40 miles. Full beam on the headlights stops functioning. I have very little knowledge about truck electrics. Any ideas will be appreciated.
Sounds like the horn ring under the steering wheel boss. Its a brass ring with two contacts which are kept in place under spring pressure. It could either be the contacts have worn away or the ring itself has worn through/ cracked. The steering wheel and air bag will have to be removed to check…
why do you blow the horn for 30 to 40 miles, is your driving that bad you need to warn others, the lights must get fed up by then and think blow this I’m out.
A Scania at that age I would suspect the wiring loom, the flexy section of the loom between the cab and chassis is famous for broken wires.
alfa man:
A Scania at that age I would suspect the wiring loom, the flexy section of the loom between the cab and chassis is famous for broken wires.
Alfaman love your badge and I love its meaning 
…So off topic why are my local alfa dealers totally useless …will say alfa Italy are really helpful
norb:
alfa man:
A Scania at that age I would suspect the wiring loom, the flexy section of the loom between the cab and chassis is famous for broken wires.Alfaman love your badge and I love its meaning
Dealers in the west of Scotland over the last few years have been crap, if I ever needed a dealer only part or some tech info I would use Western in Edinburgh.
Even the Independent sector isn’t up to much, I used a so called specialist in East Kilbride to replace the cambelt and sort the egr on my last 159, the motor was never the same. turns out when he removed the egr to clean it he dropped carbon deposits down into the dpf.
Ended up spending £350 at a tuning specialist to get a remap removing the egr and the dpf, that being said with all that exhaust crap being removed the motor went like a rocket 
A common problem, but luckily there is a cheap solution. All you need is a gallon of petrol and a book of matches…