sam_unit_removal_and_repair_3_lines_fault_smart_fortwo_451¶

4 excerpts.

Excerpt¶

youtube.com/auto_knight/sam_unit_removal_and_repair_3_lines_fault_smart_fortwo_451 · p. 1 · Applies to: 450, 451, 452, 453, 454, #1, ebike

in today's video I'm going to be removing the Sam unit from this smart and dismantling it and inspecting it for poor solder joints before we get started I'd just like to say a massive thank you to all of you who've bought me a coffee all generous donations through buy me a coffee do get fed back into the channel to buy tools and equipment and to keep this channel going it's greatly appreciated and thank you those of you who follow my channel will know that this car has been a little bit of a lately on two occasions I've gone to start this car in the morning and I've had the three lines on the dashboard the dreaded three lines indicating some form of transmission issue in terms of actuators and Communications I ran a scan on this car and there were some fa codes related to implausible signals and communication between the transmission module and the Sam unit something I've had problems with in the past on these cars uh is the Sam unit uh the Sam unit which is the signal acquisition module unit uh lives under the dashboard on the left hand side it's uh it's in just the worst place to be destroyed by water from any windscreen leak you may ever have uh and they also are quite prone to having poor solder joints I've actually repaired one on the previous car it was a 450 quite a late one uh 700cc the earlier 600 CC cars had what's known as a zunit which stands for centrala in electric these uh also had their issues but back to the 451 Sam units do have problems and they can cause all manner of issues in terms of coms the Sam unit is essentially a communication Hub it contains fuses it contains relays a micro processor and all the other control units communicate with it it's crucial that it's in good condition and that there are no defects within it's a terrible night out there there's a storm there's hurcan winds uh and it's it's really horrendous so it's a great time to be doing this the absolute beauty of these little cars is that you can actually work around them even in a single garage this is quite a large single garage but even so it's it's great to be able to do this now the only downside really is is lighting it's not the brightest in here but we'll do the best we can first thing we need to do is to get the carpet up cuz we need to disconnect the battery and once we have the carpet out the way we remove this poyene wedge we can now see the battery and we could just disconnect this negative terminal here just leave that wire there and then uh crack on removing the Sam unit but I'm not going to do that because I want to get the battery right out never had this battery out of this car and I want to clean it underneath also just by disconnecting this and leaving it here there is a risk that it could make contact again unless I really tied it up around around the back here and that really mustn't happen for reasons that you will find out very shortly and disconnect the battery terminal this 10 mm nut is loosened this little clip can be disconnected and this is the retaining bracket for the battery disconnect this battery vent pipe and it's now a case of removing this battery little bit of a bugger to get out just due to the limited space we've got and then this is a bit of a pain as well we can remove this from here which makes it marginally easier I'll be removing this battery off camera because I need all my hands well all two of them the battery is out you can see just general dust and dirt and leaves and things I'll be giving that clean [Applause] [Music] out it has all been hoovered out I'll probably just give that a wipe with the wet wipe before it goes back together the Sam lives under the dashboard on the left hand side by pulling a lever here at the back it hinges down and it simply pushes up disconnects it from the bracket it can then be lowered at this point you will see all the connections on the back it's a good idea to take a photograph of this although most of the connectors I think are pretty much only able to be fitted in one place due to cutouts I'm going to start disconnecting things as you will see progress can be Swift and you can get this thing disconnected very quickly the only thing thing left now is

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youtube.com/auto_knight/sam_unit_removal_and_repair_3_lines_fault_smart_fortwo_451 · p. 2 · Applies to: 450, 451, 452, 453, 454, #1, ebike

the positive terminal from the battery it's underneath this red cover this little cover is prized off with the screwdriver it's very important not to break it but if you look at it here you can see where the little Clips are now this little cover has been removed this reveals the positive terminal from the battery this is a little 10 mil nut a lock nut that needs to be undone uh now the reason I said the battery needed to be disconnected and it was really important is because if it was still connected this would be live and in undoing this if the tool that you're using was to touch any point on the car that's ground it could cause well it would cause life to ground situation and it could potentially light this cable up like a Christmas tree and uh cause a fire so really important don't get near this until the battery's disconnected we're going to loosen this now and remove it this is removed and the nut stays with the cable it's important to state that I did once actually find one of these slightly loose on a car that was displaying all sorts of electrical Oddities so um if you ever do have some really random electrical FS do check that that is tight to the Sam obviously battery disconnected first and the Sam unit is free to leave the car and as you can see that's all there is to removing a Sam unit certainly nothing to fear unfortunately what lies within it is rather more complicated and here is the Samu in more detail part numbers an array of fuses they're all facing different ways that plays up with my OCD how sad is that I'll be putting those all the same way around and on the other side more fuses heavy duty ones here and you can see all the connections here now I can't stress this enough this is an expensive component and the best thing to do is to take it somewhere clean and dry um I'm in my kitchen this is my kitchen table got an old tablecloth down and this is not something to be rushed we don't want to break anything we don't want to damage anything we need to get this open and then we can examine the circuitry and see if we've got any dry joints in here which I've had in the past on a 450 700c uh this is a well trodden path I've already uh done one of these in exactly the same location um I wonder if I'll find exactly the same uh issues um whether there'll be differences inside in terms of the actual Sam unit but I wonder if I'll find the same sort of problems with the dry solder joints that are fractured so to take this apart we have a series of clips that need to be released again gently I don't want to break them now it's a good idea to not create any static which could potentially damage this circuitry so no nylon knickers or polyester now this does open up further so you can access the circuit boards beneath remove these large fuses and note the order of where they were and with these outer tabs press in and these little plastic tabs released from here on both circuit boards you begin to see how it all comes apart as I say proceed really slowly there's no way we want to rush this or this damaging anything after some careful manipulation taking care not to damage any of the pins the entire inner structure will come free leaving just the empty case it is then a case of very carefully opening the unit up it does have this flexible ribbon type connector here and they're actually quite stiff but with care it is possible to open this up by removing some tabs some further tabs around the outside and a couple one in there and one in there can also release this section here which

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youtube.com/auto_knight/sam_unit_removal_and_repair_3_lines_fault_smart_fortwo_451 · p. 3 · Applies to: 450, 451, 452, 453, 454, #1, ebike

gives further access to even more circuitry and even more joints that could potentially have failed I have immediately spotted some that are not looking too good but it's beyond the scope of this camera to be able to point them out what I think I'm going to do is to is to take a photograph of this and then print it off and then I can actually go over it all in detail I think I'm going to get a magnif F glass as well so I can check every joint but I've definitely spotted a few that look really dodgy so they'll be redone I have identified several barad joints across this Sam unit and to make this process easier I have broken this up into three sections so we've got this horizontal section here and I've taken a photograph of it printed it off and then I can mark the areas here that are there in pink that need to be resolder I have taken some photographs um with my iPhone and zoomed them in which is the easiest way to do it I'll put a couple up on the screen now so you can see just how bad some of these joints are next we've got this surface here and this corresponds to that and we've got a few bad ones on this board as well um this part of the board there's four I think yeah four that need do in on that and then finally this little section here and there's only one that is questionable on that one thing I have found really interesting and it's almost reassuring is that that second one down there just by my fingernail there that's quite a bad joint it's hard to see but it is bad that corresponds to pin number seven on here and guess where that goes to the transmission control module coincidence let's see all the soldering is done and on the whole I'm quite happy with it I'm going to use some electrical contact cleaner now just to clean the board and just a little I'm using a little tiny brush just make sure that there are no little pieces of slda or anything like that that could cause problems with the board clean I'm going to take some pictures just so so I can show you uh my handiwork these don't be too over critical bear in mind I am a ex main Dealer car technician we don't we didn't repair things like this we replaced the Sam unit was defective you put a new one in if the engine ECU is defective you put a new one in we certainly wouldn't be dismantling things like this and my soldering is best described as average I'll let you make up your own mind getting the heat settings right can be difficult cuz you don't want to burn the board but sometimes you can't melt the old solder unless you go up a bit in terms of the temperature but we got there in the end these two here were redone as was this one and also this one one here moving on to the center section there were way more this one was redone this one this one here three down here there there and there and finally on here it was just this one we can now start putting this back together first of all there's the center section you will see that there are lugs that line up with holes in the circuit board and these two little little Clips here pass through those two square holes right there and just check that those two Tabs are through which they are so that is refitted we now need to carefully fold these sections back down and it locks into position with the tabs just there and there and then the same for this one again it locks into position with some tabs that is in place it is now case of fitting the uh the internals to the case can see this uh cutout here

Excerpt¶

youtube.com/auto_knight/sam_unit_removal_and_repair_3_lines_fault_smart_fortwo_451 · p. 4 · Applies to: 450, 451, 452, 453, 454, #1, ebike

that is for the main battery feed and it's now a case of ensuring that the connectors all pass through the back of the unit we can now refit the cover and refit these fuses bonus points if you can remember the order I can't I'm going to have to check my phone okay so here we are that one is vacant and then it's red Amber and green shouldn't be difficult to remember really because it's basically like traffic lights I took out the fuses one at a time and put them all around the same way because I'm me it's difficult being me but I'm happier with it like that this is ready to go back into the car back at the car so it really is now just a case of reconnecting this essentially reverse order of uh disconnecting it we'll start with the uh live terminal and then just get everything plugged back in I need both hands for this it's quite dark under here so I'll be back when this is plugged back in everything's reconnected that positive terminal is tightened don't go crazy with it it's on a circuit board remember you don't want to tear it off the circuit board when you tighten it and the cover is also refitted it's now a case of locating these little clips into this bracket ET they kind of pull down from the top if you see what I mean you got to get it you got to get the Sam unit above it and then pull it down and with the lugs located there we can just lock the Sam into place like that and that's refitted battery tray has been cleaned ready for the battery now you might have heard people talking about the airon drain that can block up and fill this area with water well there it is that's the air con drain if you ever need to clear it out just goes up to the heater box up there there it is unrelated but useful to know the battery is back in place bracket refitted 10 mil nut tightened we refit the wiring up there and we refit this little clip here for the loom and the Breather for the battery to allow the hydrogen gases that they produce to vent to the outside of the vehicle positive terminal is tightened it's just now a case of connecting the negative the negative battery terminal has been reconnected there is no smoke which is always good I am back in the car okay we got to start up reverse neutral and uh drive manual mode auto mode I need to take this car out for a decent drive I'm back from Road testing this thing and it is behaving itself at the moment now as it was an intermittent fault there's no guarantee it's fixed time will turn tell but I'm pretty confident in some of my findings within that Sam that I may have nailed it especially that terminal pin seven solder joint and that after all is one of the communication routes between the Sam and the transmission module and that kind of links into some of the Full codes that I had so hopefully it's fixed I hope you enjoyed the video and I do hope it's been useful if you enjoy content like this please do subscribe to the channel numbers are climbing and it's great thank you very much for watching and goodbye