06 Vito W369 Strange Light problems

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seanrourke592

New Member
Joined
Jan 8, 2020
Messages
13
Location
diss, norfolk, uk
Car
mercedes vito van 2006
So I thought I had a simple problem with the dashboard not illuminating. However it seems a bit more bizarre than that. Heres what happened today:
went for a drive and dashboard not illuminated. all the warning lights and indicatorlights etc work fine. got home and parked outside my house as usual, got out and blipped the lock. noticed that the front offside side light was on. assumed i had flicked the dial too far and went back, blipped it and opened the door. The dial was in the off position, the dashboard was lit up lovely and the "lights on" warning was buzzing!!. switched it to park lights and they worked and buzzing stopped. back to off position and everything off. shut the door all lights off. blipped the lock and the front offside side light came back on. in the end i left it unlocked and it was fine. went out again just now, came back and switched it all off and blipped the lock and its all ok!!! (except dashboard still in the dark). I hope all this makes sense to someone. Is there some sort of electronic gubbins controlling all the lights that could be having a brainfart?
 
This sounds like your SAM,
and considering your earlier post I would imagine that your fuse box has ingress of water and has caused the SAM further deterioration.
Similar things can happen when water gets to other components, the multi function light switch for example.
Water getting in by the screen seal can cause that.

My first step would be to remove the contents of the fuse box and look for evidence of ingress there.
 
This sounds like your SAM,
and considering your earlier post I would imagine that your fuse box has ingress of water and has caused the SAM further deterioration.
Similar things can happen when water gets to other components, the multi function light switch for example.
Water getting in by the screen seal can cause that.

My first step would be to remove the contents of the fuse box and look for evidence of ingress there.

That all sounds very likely as I have had an occasional leak around the window but only rarely and the cover has been off the fusebox for a while (oops). Think I need to check it out and see if there any water in there. what is the SAM? will it be permanently damaged and need replacing.
 
The drains for the screen are above the fusebox, and often block.
The bonnet seals to cause the water to be directed to the drains often fail.

If your cover has been off I would expect the SAM to be bye bye and the ECU and TCU are also at risk of being affected.

On removing the SAM you can get the number off the front, a replacement is circa £80 - £100 off Ebay, it's plug and play, but some 2nd hand SAM's have their own issues.
The ID number needs to be the same.

Hopefully you're ECU and TCU have escaped. I tried a replacement TCU some years back and as much as the seller believed it was plug and play my experience was that it isn't.

The ECU is married to other components, so here you would need keys, steering lock, and others might enlighten as to other associated controllers, a bit more complicated.
If you can get this lot for £550 you're doing well.

In the short term I would get the electronics out of the fuse box and into a warm dry environment.
I would remove the fuse tray and get below all that to ensure it's dried out. It's a nice reservior down there.

On re assembly of the box ensure the cover fits well, the front o/s corner can drop. I used a heat gun on the earlier Viano to reform it, as I believe it's critical for the box to have integrity, there's too much water swilling about above it.

There was other evidence of heat abuse on that Viano though, prior to my ownership.

As for the screen, if that's passing water into the cab, it'll need to be removed and reset. A good screen fitter would be ok with that, but there is risk of losing the screen if it has any weakness.

I'm hoping you won't need as much luck with this lot as it sounds like you might need.

Sorry nearly forgot,
the SAM is the Signal Aquisition Module. Your switches (for instance) tell it what you want, side lights perhaps, it will then switch them on for you (ideally). It is underside of the fusetray, with a screw down through the tray to hold it. Screw out and then the SAM rotates some for removal. First the tray needs lifting out and the many plugs into the tray and SAM need unplugging, carefully one or two are delicate.

This isn't a job that can be done half hearted, you've to get right in there. If you're worried about the complexity you might be better passing to another, but it isn't as bad as it sounds.
 
Last edited:
The drains for the screen are above the fusebox, and often block.
The bonnet seals to cause the water to be directed to the drains often fail.

If your cover has been off I would expect the SAM to be bye bye and the ECU and TCU are also at risk of being affected.

On removing the SAM you can get the number off the front, a replacement is circa £80 - £100 off Ebay, it's plug and play, but some 2nd hand SAM's have their own issues.
The ID number needs to be the same.

Hopefully you're ECU and TCU have escaped. I tried a replacement TCU some years back and as much as the seller believed it was plug and play my experience was that it isn't.

The ECU is married to other components, so here you would need keys, steering lock, and others might enlighten as to other associated controllers, a bit more complicated.
If you can get this lot for £550 you're doing well.

In the short term I would get the electronics out of the fuse box and into a warm dry environment.
I would remove the fuse tray and get below all that to ensure it's dried out. It's a nice reservior down there.

On re assembly of the box ensure the cover fits well, the front o/s corner can drop. I used a heat gun on the earlier Viano to reform it, as I believe it's critical for the box to have integrity, there's too much water swilling about above it.

There was other evidence of heat abuse on that Viano though, prior to my ownership.

As for the screen, if that's passing water into the cab, it'll need to be removed and reset. A good screen fitter would be ok with that, but there is risk of losing the screen if it has any weakness.

I'm hoping you won't need as much luck with this lot as it sounds like you might need.

Sorry nearly forgot,
the SAM is the Signal Aquisition Module. Your switches (for instance) tell it what you want, side lights perhaps, it will then switch them on for you (ideally). It is underside of the fusetray, with a screw down through the tray to hold it. Screw out and then the SAM rotates some for removal. First the tray needs lifting out and the many plugs into the tray and SAM need unplugging, carefully one or two are delicate.

This isn't a job that can be done half hearted, you've to get right in there. If you're worried about the complexity you might be better passing to another, but it isn't as bad as it sounds.




Cheers M80,

Thanks for your help and advice, can I pick your brains some more

I have had the fuses out... took a bit of wiggling. Fuse box looks fine and dry, no evidence of water. they all look ok?

I have narrowed the symptoms down to this:

dashboard not illuminating ( I can live with that)
Side lights stay on when light switch in off position. I cant turn the side lights off (well i can switch one side off when i move switch all way over to park lights). Unfortunately this drains my battery.

as a side issue i have had problems with my bonnet release cable sticking (cable snapped and I am useing mole grips to open it), i can sort it but that wouldnt affect the lights in any way ie. van thinks bonnet is not shut properly. I cant see a sensor on the bonnet but just in case/

also the nearside sidelight bulb blew a long time ago. (this helps at the moment when parked, i put nearside park lights on and only the rear lights up so it drains tha battery slower). that wouldnt affect this situation would it?

Still not sure its the sam but I am going to but one on ebay anyway because if it works its a cheaper fix than my local garage... lol.

Cheers. Sean
 
I would need to check on mine, but think there is a bonnet switch that prevents front wiper / washer use while the bonnet is open. Of course it would also be used for the alarm. This is the case with most other MB models, just not sure about the more basic Vito. In any case it wouldn't affect the lights.

That's good news relating to the fuse box not being a reservior. But I've seen SAM's go down in dry enclosures.
I'm still thinking this is SAM or multi function light switch (if that's seen some moisture).
See how you go with your eBay SAM. I have a 639 545 03 01 [03] SAM (not sure the [03] bit is over important). It has known faults on interior lights, but I use this for diagnostics in that if I instal and it solves (whatever) issues but introduces the known fault then the SAM is the problem.
You may find the eBay SAM has its own issues?? I can always send this one to you for diagnosis if the eBay situation fails, but I would like it back.
 
Extra thought,
when buying the SAM for a few extra quids you might consider buying one still attached to the fuse board, along with the clip on fuse carriers.
If you decide to add extras these clip on fuses can be worth their weight.

If your fuse board is the A639 545 0401 I have created a much more user friendly reference chart for fuse identification. Trying to use the manual on a dark rainy night is near impossible.
 
Extra thought,
when buying the SAM for a few extra quids you might consider buying one still attached to the fuse board, along with the clip on fuse carriers.
If you decide to add extras these clip on fuses can be worth their weight.

If your fuse board is the A639 545 0401 I have created a much more user friendly reference chart for fuse identification. Trying to use the manual on a dark rainy night is near impossible.


Yep, thats my fuse board too so the reference chart would be useful, especially as i dont have a manual. I have ordered a new sam 639 545 03 01, the same as mine and it has the fuseboard attached. Will let you know how it goes..
 
I have the chart on XL, the forum doesn't allow this to be uploaded.
I can photograph it and upload that,
but if anyone can suggest a way to pass the info in a form that still allows editing I'm all ears. My chart is from my Viano days so has more fuseways used than most so a Vito owner might wish to amend, as I have, and again when I added my electric seats (from the clip on fuses that I've now used up).
 
I have the chart on XL, the forum doesn't allow this to be uploaded.
I can photograph it and upload that,
but if anyone can suggest a way to pass the info in a form that still allows editing I'm all ears. My chart is from my Viano days so has more fuseways used than most so a Vito owner might wish to amend, as I have, and again when I added my electric seats (from the clip on fuses that I've now used up).


do they not allow email addresses to be posted here?
 
email sent, you can delete from here if you like.
 
After days of faffing about with the electrics and ordering a replacement sam unit the van has decided to work... properly and completely. Even the dash board is lighting up.. Ha ha. I have the new sam coming anyway so i will see how it goes. It is probably going to go wrong again but I wil lbe ready for it. Now if it can just self fix its other problems I will be happy.
 
Could this be that moisture around the light switch has dried out?
Have you had less rain, or parked at a different angle?

I think there is value in holding a SAM that's good, or at least with known faults, like my original SAM.
When the van is behaving I would instal the replacement SAM and return if it isn't all good.
 
Could this be that moisture around the light switch has dried out?
Have you had less rain, or parked at a different angle?

I think there is value in holding a SAM that's good, or at least with known faults, like my original SAM.
When the van is behaving I would instal the replacement SAM and return if it isn't all good.

Funny enough its the opposite. Its been lashing down here, but maybe its just dried out? either way i have a replacement coming so i will kep it in reserve. I dont trust the van for it not to happen again.

Thanks for all your help and advice, probably saved me a fortune in garage fees.
 

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