Chassis lighting problems (1 Viewer)

[Popty]

Hi all, can anyone help me.
I have a 2005 Fiat Ducato, Swift Sundance 590RS motorhome, I have now experienced a lighting fault with the chassis electrics, as it will be going for MOT soon I decided to check all the lights, if I switch on all the lights, side/tail, hazards, rear fog, reverse & brake lights the problem occurs, the lights go dim/bright & alternate, as a retired motor engineer I thought "easy" bad earth lol, not so easy as I ran a separate cable from the battery earth to the rear light cluster & this did not help, next I checked the voltage at the rear lights, on tail lights I only get 9.2volts, indicator voltage is slightly less, so I thought it will be corrosion in the Fiat/Swift junction causing high resistance, found the rear light wiring loom & it disappears into the chassis box section, however I can't find out where it comes out of the chassis to connect to the Fiat chassis wiring (if it does) , if I can find out where the Swift wiring connects to the Fiat wiring I can test it and if need be run a new 5 core cable to the rear left & right lights, can any one offer any help or assistance please

 

[David and Sally]

 

[HugoBNB]

Welcome Sounds like a Job for a pro. You could be on forever trying to track it down. Good luck.

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[Speve]

Welcome Sounds like a Job for a pro. You could be on forever trying to track it down. Good luck.

He was a pro

 

[HugoBNB]

Perhaps a clairvoyant then?

 

[Popty]

Just need to find the Fiat/Swift chassis wiring interface is, then the rest is easy, new 5 core cable & rewire the rear lights

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[ambulancekidd]

I think I'd go for the option of running new cable, the old cables sound a bit dodgy & I know I'd rather be safe than sorry.
Good luck & please can you keep us posted with how you get on?

 

[pappajohn]

Waterproof junction box attached to rear chassis rail.

 

[TheBig1]

chassis front junction is just behind the uk drivers seat under the van

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[PeteH]

Just a thought. Is it not "new" enough to be a Canbus system. They are in my experience, prone to even the smallest degradation of the earthing?.

 

[Spriddler]

Ask Swift for the location of the interface? I assume they added the hab wiring.

 

[Popty]

Hi all, no junction box at rear chassis rail, cable from rear lights goes into chassis box section about a meter from the rear lights, no junction box under cab just behind driver seat, its not can bus, everything is hard wired, and I have sent a message to Swift but due to covid-19 they are closed till September, that is why I need to try and get a resolve soon as we are away for 3 weeks soon and mot just after we return

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[Popty]

Morning all, after a restless sleep last night, I have had another look this morning & I have found some wiring looms, that I think may be for the rear lights ,I removed the plastic footwell covers in drivers side & passengers side & found looms going through the footwell into the chassis, both looms have 5 wires in & am now going to check what these wires do, does anyone have a wiring diagram for this vehicle or know the wire colour codes please