Got an Erratic W221 S320 CDI, need help!

AliZafar5

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Gents,


I recently brought home a 2008 57000 kms driven W221 320 CDI which has was parked for a long time in pretty muddy conditions. The car had snails and other insects infestation and the engine bay was full of dirt till about had of the engines height.


After replacing the main as well as the auxiliary batteries, removing the under shields and a thorough underside wash, I drove it for two days. The car drives fine and shifts well but keeps doing these erratic things, like the speedo maxing out while the vehicle is parked, the tail lights flicking/flashing and the air con blower turning on and off on its own and doesn't respond when the blower speed is increased or decreased.


I decoded the VIN and the car does have K11 option Adaptive Stop Light Flashing, not sure what that is but as far as I understand its part of the Presafe system where tail lights flash under emergency braking but not sure what triggers it as its doing that while parked.


Any suggestions/comments are welcome!
 

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Hello and welcome

Water / mud in the electrics - corrosion in the connectors and SAM’s

You could be chasing that for a long while
 

bembo449

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Start with a star sesh but as botus says you may be on a looooooong road, unless you can find a ginormous bag of rice to put it in for a couple of days to dry it out
 
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AliZafar5

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Thanks for the replies!

So what are SAM Units? Where should I be looking for them? I got it hooked to an advanced diagnostic (not Star) while it had many stored codes which were cleared, it only had one current code related to blower regulator.

Can some one kindly share the part number for it? or an excerpt from parts catalog? I tried looking for it and was only able to find it for vehicles till 2007.
 

Botus

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SIGNAL AQUISTION MODULE = SAM its a fuse, relay and programmable control box of tricks, that links up systems in the car and can be coded to turn toys on and off.

There are coded ONLINE to Mercedes Benz servers to get the specific toys and set up for each car.... so not plug and play at all

There are two, one beside the rear battery you say you changed.... and another under the bonnet opposite side the small battery

I think I'd disconnect the batteries and start remaking every multiplug connection you can find spraying ACF50 on anything electrical (its magic developed to stop / remove corrosion in the aircraft industry and perfectly safe on electrics)

then connect it all back up with a big power supply and just wipe any fault code, then go for a 5 mile drive any real one will come straight back and you can see what mess u r facing

this could be a very labour intensive and financially costly exercise that gets you nowhere. It would probably be kinder to kill it for all concerned
 

Wighty

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When you say drove it for 2 days , do you mean pottered to the shops or big motorway run ?
Maybe leave the bonnet up and disconnect all electrical connections and box covers on a nice sunny day ?
 
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AliZafar5

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Thanks for the reply.

Is ACF 50 a contact cleaner? We don’t have this here so I will have to find a substitute.

The batteries I replaced are the front one in the engine bay 95AH AGM and a tiny 1.2 AH next to the steering column. I am not sure if I have a third one, I have seen contradictory info online, in places it says it has three and other places say that it has two. MY of my car is 11/2008 would any one here be able to confirm?

It was city driving taking it to shops and car wash. Nothing on the motorway yet.

The car is beautiful and low mileage and is in good shape otherwise, so I’m gonna try out both of the suggestions and hope for the best.

Would you know know what K11 option is? In the vin decode, it says that it has DPFs but I Inspected the exhaust tips and they have soot in them. Is that normal? My land cruiser with DPFs has 0 soot and the exhaust tip is silver but that’s a 2016 car.

People here tend to get rid of dpfs as we have bad high sulphur diesel and they usually don’t use the correct engine oil. So I suspect that either the car doesn’t have it and has been removed.

Also, what engine oil is the correct spec for this OM642.930 engine? Should I be looking for spec 229.3 or 229.31 or 229.5 or 229.51?
Please advise.
 

Botus

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as far as I know the higher the number the better.... 5 is long service life posh oil (3 is cheap nasty) spec 229.51 I'm guessing would be C4 in the real world. You want one that's suitable for decent diesels.... the numbering system most oils use was updated in modern parlance outside Mercedes ideas see here: https://www.oilspecifications.org/acea.php

you should be looking to change the gearbox oil if the cars a good one...

ACF50 is a thick purple weird concoction and definitely not contact cleaner.... it makes stuff look like new, if you wipe on plastic it makes it look good as well. BMW bike dealers use when washing the bike after servicing the bike (don't get it on brake discs takes 6 months for them to work again and no amount of rubbing or thinners gets it off....) a bit of a stupid test as this is not exactly what its for.... its designed to seep in to seams between aircraft skin, to solve issues with corrosion but might give you ideas about other products https://www.bennetts.co.uk/bikesoci...nts/tested-acf-50-corrosion-protectant-review

battery wise you are at the cross over of small front, large back battery - to just having the main front one - behind the rear seats, accessed by pulling out the trim cover in the back of the boot, you may find a huge 25kg battery... or may not. But you'll find lots of electrical stuff anyway
 
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AliZafar5

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So I removed and dismantled the front and the rear sams and fuse boxes and cleaned all contacts including fuses and relays with and contact cleaner and it fixed all the issues!
 

Botus

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So I removed and dismantled the front and the rear sams and fuse boxes and cleaned all contacts including fuses and relays with and contact cleaner and it fixed all the issues!


if you had corrosion visible I'd buy in some ACF 50 and spray it all over the circuit boards. It really is magic and safe on electrics.

if you have the RFK (rear camera) on the boot made of aluminum as they were up to 2007.... I'd strip that down and without getting on the sensor or lenses dry out the water and remove the white powder, then carefully apply some ACF50 inside that too.... later ones got a plastic camera that's much cheaper and a bit better. Its a shocker inside, more like a swiss watch than a 10p sensor from china. No wonder they used to charge £750 for it.... and the rudimentary night vision stops if you fit the iPod interface kit. An extremely rare later model interface 2 kit with a different loom re enables it (I just did it on mine...) I've only ever located 1 worldwide !
 
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