2013 Viano Interior Lights don’t work

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New Member
Feb 23, 2021
Yorkshire, UK
2013 Viano 3.2CDi Ambiente
Hi all, new to this but hoping someone here might be able to help me.
My Viano went into the garage last week for a new alternator belt and pulley. When it came back, the interior lights no longer work and I can’t see why. I have checked the fuse under the passenger seat and the one in the main fuse box under the bonnet and they seem fine. To confirm, the rear lights work from the button on the dash, but nothing happens when you unlock the vehicle or open any doors. Also, and I suspect key, while I have control of the rear heating from the roof console, I have no lights in any of the other switches on that console which control the lights or the alarm sensor bypass switches. This makes me think it is a power issue.
Please does anyone here have any ideas where I should look next? The fuse tables seem quite vague really. I’ve checked the sockets and wiring behind the roof console and they seem fine. Might need to get my multi-meter out next. Thanks ever so much in advance,
Do they switch on individually?

Does it fail to switch them to automatic by the lower section of the dash switch?
The LED on that should be off for automatic switching (doors, and unlock).

Then, in case the SAM has got confused you could try disconnecting the battery for perhaps 30 seconds.

The fuse under the seat won't have any part, although fuse 18 (25A) is for the overhead panel. That's top right.

Fuse 23 on Fuse bank 35 should be the one.


  • Viano Fuse Board.pdf
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If you are going to check at the lights there should be a permanent 12volts +ve, it is the -ve that's switched, for the general lighting, the map lights and the ambient lighting.
Dear M80
Thank you so much for all that. Interesting because my fuse guide has the interior lighting as fuse 23 on bank 34 (which doesn’t exist anyway). I love that fuse chart, have printed a copy for future reference.
So I have now checked the right fuse 23 but still no joy. Will try disconnecting the battery later this afternoon and report back. Will also check voltage at the lights at the same time.
Do they switch on individually?

Does it fail to switch them to automatic by the lower section of the dash switch?
The LED on that should be off for automatic switching (doors, and unlock).

My chart assumes your fuse board to be the same as mine, and the same functions are wired out to .
There were 2 versions on earlier models. It's worth checking that the A639 number is the same, that's embossed into the middle of the board.

The problem with disconnecting the battery is that some functions will require normalising.
Make sure electric sliding doors are closed.
Windows will need to do a full cycle down /up.
Steering may need full travel left /right.

The fuse enclosure can be awkward for some to close properly, be sure on that one if moisture gets in the SAM doesn't last long. And I have seen a fuse enclosure distorted by heat, so doesn't seal. There's just too much electronics in there to be casual with it.
Hi M80.
I’ve tried everything and still no joy. The rear lights can be controlled from the switch above the stereo, and the lights off switch does light up red. The map and door lights at the front do nothing, either when the doors are opened or manually. I’ve found my multimeter and checked for voltage at the bulbs and there is nothing at all. The push buttons for the map lights, light controls and the alarm override are all in darkness and do nothing, which is what makes me think it is power somewhere. There are two thicker wires coming in to the unit (red and brown) and I wondered if I should check the voltage there perhaps?
Just to add to my puzzlement, tonight the two alarm buttons by the mirror appear to be working fine again?!?
I did check the main 10a fuse again yesterday and it is fine, this time I checked that there was actually power to it and coming through it, and there is. Anyone know where this cable goes next? I’m assuming there might be a control box located somewhere which might be my next port of call.
Many thanks.
I can't give a definite answer but only as I would expect.

I would expect the fuse to supply a permanent feed to the lights.
The negative switching to my mind would be via the SAM. On these there is just one SAM in the fuse box at the front.

I would expect the map light switches to not be via the SAM and instead short to chassis.
Other switches would tell the SAM to switch.

The fuse has 2x small areas of conductor exposed, so next time there are no lights you might check both sides to see if the voltage is passing that far at least.
I have seen fuses to look good but be unreliable, maybe a new fuse is worth the effort.
Thanks M80, that gives me some more to think about. I did check the voltage on that little bit of blade, and it is definitely getting through. Since the rear lights all work (except when the doors are opened) that sounds good. The map lights don’t work, so that is strange, might try poking behind the light console again and see what voltage I have there. Is there anything else the SAM would do? Anything else that could have failed? Is the SAM located under the main fusebox? If so, since the work the garage was doing was on the front end, there is a good chance I’ll find the problem there. 🤞
Thanks again for your help with this.
The SAM does a thousand and one things. Anything that isn't engine (that's ECU, same fuse box) isn't transmission (that's TCU, same fuse box) all are switched by the SAM.

In the fuse box, the SAM is screwed into the fuse board plate from underneath. To access the SAM the fuse board needs disconnecting and removing complete with SAM. Not for the faint hearted.

ECU sits toward the front of that, with the 2 black multi plugs into it. They slide lock, unplug and ECU pulls up easily.
TCU below that.

Any moisture in there can be disastrous, if it's raining do it another day.

I've had SAM's do strange things, inside lights being one. But that had another issue also.
I've replaced SAM's and carry a spare for diagnostics, as it has those 2 known faults.

You might try removing all lamps (bulbs if you prefer), or unplug all. Then install a good lamp into main and map. The SAM can self protect and disable if there's a short.
Ok. I’ve watched a quick Youtube clip on removing the SAM and you’re right, it looks interesting. Something is working because I’ve just realised that the blue Ambiente led’s do come on when the door is opened. I think I’ll buy a pack of bulbs to start with and try that first. Thanks for all your support on this one.
You're welcome.
The SAM is only worth removing to get the correct ID for replacing. There is nothing serviceable about them.

I didn't know ambients could be blue, mine are orange.

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