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post #1 of 43 (permalink) Old 01-03-2017, 12:27 AM Thread Starter
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Button bank & Latch relays

This idea for using unused switches from my button bank originally came from Limoak and the thread for that article can be found:
451 Button Bank Mod

I give him full credit for the idea and mine is just an embellishment of using more than one switch.

Latching relays like the type we used can be found for under $3 each on Ebay.
1 Channel Latching Relay Module 12V with Touch Bistable Switch



There are 6 buttons total that one would think would be a candidate for modifying. To make any of the buttons usable you must disassemble the button bank and snip off the 4 locating tabs on a button to enable it to be pressed (more on that at the end). But buttons 1 & 6 are used for the heated seat option. If you have that option you're not going to use those buttons for this mod. If you don't have heated seats you don't want to use those 2 buttons even though they are a momentary switch, one push is for low and the next press is for high and the switching is done via transistors so they can't be used for our purpose. Lastly along that note is I went ahead and snipped the tabs from these buttons and when they were reassembled they would not press anyway, so I don't know if non heated seat cars use a different button bank than the heated seat ones or not, but anyway they don't push, just leave 1 & 6 alone.

Now I presume that all the Fortwos use button 5 for the TMPS tire pressure monitor, so that one isn't a candidate either. If you have a factory alarm 4 isn't available for you to use. If you have factory fog lights then 2 isn't usable for you. If you have a rear fog light option as in the U.K then you can't use button 3. If you have a US Pure then you likely have 2,3 and 4 open, and that is the option I was working with.

Now I have DRL's and Fog lights that I have on separate switches that I wanted to graft to the button bank.



And also I have a 200 watt power inverter that I have on a separate toggle switch to run my subwoofer/satellite sound system, so I likewise wanted a switch from the button bank to be used for that. So I had 3 available button bank switches, so I ordered 3 latch relays.

Now my DRL paddle switch was mounted right behind my turn signal stock, and my fog light rocker switch was mounted under the dash by my 12 volt cigarette lighter plug( if you want to call it that or a power port). Now both of these items was fed from the same switched power source that I picked up from the SAM and I used a 25 amp circuit breaker on that circuit because my other fog lights were halogens and pulled more amperage than the COBB LEDs in my newer fog lights.So I knew I would be powering my whole latch relay system from the same positive wire and ground wire that I fed my fog's and DRL's. I disconnected both switches and snaked the wires back down under the dash to beside the cigarette lighter.

Now the relays are relatively small and I wanted them all mounted together for simplistic wiring. So I had a piece of plastic panduit like I used to use for surface mounting Cat 5 wires and jacks and also electric receptacles on the wall for computer labs. A piece of heavy plastic, lexan, or even a piece of wood paneling would work. I lined up all 3 latch relays and drilled holes in each of the relays 4 corners through the mounting panduit and orienting them all in the same direction I used plastic wire ties and cinched them down in place.



Now with them oriented the same way and the wire ties tightened I used a black sharpie to mark each relay, one for each application,DRL, FOG and RAD for radio/stereo.
Now the side of the relay with 2 connectors is the side that powers the relay to click on and off. Since I was powering all three relays with the same power source I daisy chained the positives together in series and then series the grounds likewise. So now from the 2 connector side you should have the positives together to a single common wire feeding out and the grounds should be together to a single wire feeding out.



Now the other end of the relay has 3 terminals. One says NC for No Contact, so forget that one. The one marked common is the ground for the output to your devices. Since they are all fed from the same sources, daisy chain the grounds (COM) together and connect it with the grounds from the 2 terminal side you just did. Take those ground wires and connect the ground from each device your running power to. In my case it was the ground from the DRL's, the Fogs, and the stereo. So all your grounds are connected together to one wire in essence. Take that ground wire now and connect it to the vehicle ground. There's not alot of places on the Fortwo that are not good ground candidates. So if you look up beside the SAM on the floor (to the left of where your left foot would sit as you are driving), up in that corner there is a ground post connected to the tridion floor and there is several wires connected to it from various places from under the dash. Get you an alligator clip and solder or crimp your combined ground wires you just did to it and clip the alligator clip to that ground post or the connectors coming out from under it.

Now with all the grounds connected and power fed from the SAM (we'll cover that later) to the relays, all that is left is to connect the positive wire from each device your wanting to power to the "on" terminal on the side with 3 sockets. After you do those connections you need to test your relays. Switch on your ignition to power your relays and press the test button on the relay circuit board. You should hear the relay click and the device come on. Press the test button again and the relay should click off and your device be off. If it doesn't work you have either a bad ground or no power to the "2 terminal" side of your relay.

My wiring ended up looking like this:


Now it's on to connecting your button bank: Now the 2 tiny white wires and plug, plugs into the socket on your relay board and touching those two white wires together is the same as pressing the black test button. Now here is where I messed up. Through looking at the posted diagrams on Evilution and what I found on the internet the button bank merely grounds out a wire when you press it. So I thought what the heck if it just grounds when you press a button I'll just ground one of each relays white trigger wires and I'll only have to run one trigger wire from each relay to the button bank. I was wrong on this. If you do it like that, when ever you turn on one relay, they all kick on. You have to have both trigger wires isolated to the button bank for them to work. The other important thing to note on the button bank is where the pins come out of the circuit board to the wiring connector on the button bank there is a tiny #1 by terminal 1 and a 9 at the end of that row. Go by those numbers to get the right wire to splice into. I had the drawn picture from Evilution and I ended up confused. Kayne was diagraming a U.K Smart and I found our US Smarts don't have a wire on pin 9 so I got messed up thinking that wire 8 was wire 9 and wired mine wrong the first time. It's easy to mess up. The button bank diagram looked the same to me and I couldn't tell if I was looking at the plug that plugged into the bank or the back of the button bank itself. So be certain which pin is 1 on the circuit board and then orient it to the connector to cut the right wire.

Now this is the diagram from the Evilution site. It is the property of Kane and I hope that he doesn't mind that I posted it here. If it was wrong for me to do so I will gladly remove it.


Now remember the digram is as thoughyou were looking at the pins coming from the circuit board. Then orient yourself to see which pin plugs into the connector to designate the wires you need to work with. Now the first pin you want to work with is pin 3 because it is ground. Find that wire coming up to the connector and clip it a couple of inches from the connector. Tape up the end that goes into the wiring harness. Now look at your white trigger wires and you will see tiny red dot markings on one of the wires. Just be sure if you use the left wire on the first relay, use the left one on the other two also. If you use the one with the red dots, be sure the other relay wire matches it and connect all three trigger wires to the switch side of the ground wire you just snipped. Now you should have one trigger wire left on each relay. Pick your designated button bank button and snip the designated wire, tape up the end going back into the Smart wiring harness and connect the button side of the wire to your designated trigger wire.
Now you can test your connnections by powering up your relays and using a small metal object to touch the circuit board carefully where the rubber button would touch and it should trip your relay.

Now look at the back side of your plastic buttons and you will see 4 plastic tabs that need to be snipped off with wire cutters or bent over and broke with needlenose pliers or snipped with toenail clippers.


Now use a finger to push the button out the FRONT side of the bank. Now be totally certain that you get the right button back in the same hole. Each button is contoured on the bottom side and also oriented by a knotch on the side as you can see in the pic. Each button will only fit it's original hole. You can force the wrong button in a hole but it will not freely push or rebound correctly. I messed up. I laid my 3 buttons out in order so I could etch an icon on the button and somehow I got them out of order and cut the wrong icon on the wrong button. Now I practiced with a dremel as Limoak had done on other plastic and I was terrible. So I got out my engraver and it did a much finer line. But as I said I cut the wrong icon on the wrong button and the buttons can't be switched around to another slot. So I carefully sanded each button smooth and covered each with black tape, which is the perfect width and texture. Then I used an exacto knife and cut out my icons freehand. A fog light, a halo and a speaker and it turned out pretty good for someone like me with zero artistic ability, and the illiuminating leds shine right through it like factory.



****Now before you start this project there is one more BIG DISCLAIMER and this might be a deal breaker for some.
When Limoak did his buttom for his wind up key motor he used button 3 and there is no LED light behind that button, so if you have only one thing to pipe through the button bank then use that button. Now button 2 has a green LED behind it and button 4 has a red LED behind it and both of these LED's light up ALL THE TIME when you connect up as I have outlined. Now it's only 2 tiny LED's so I don't know at this point how much both of them draw. I would venture to guess maybe 10 to 12 milliamps each. I have not had a chance to tackle this last problem yet due to the holidays. Worst case scenario I will unsolder the LEDs and remove them if it proves to be too much if a drain on the battery. On the other side of it people might think you have a car alarm and not steal your Fortwo. I will do some testing and try to come up with a solution and I will post it here when I do. I'm sorry for this being the longest SCOA post ever, but I hate incomplete instructions and when I try to post I imagine that I am a person who knows nothing about my car except how to turn the key and drive it. Then I try to lay it out thoroughly so a child could do it. So sorry for the book I just wrote. DCO
NEXT IS WHERE TO HIDE YOUR RELAYS AND THE POWER CONNECTION TO THE FUSE BOX (SAM).
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post #2 of 43 (permalink) Old 01-03-2017, 01:17 AM Thread Starter
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Now as far as hiding the relays, there is space overr the lip of the dash on the passenger side of the console. I was able to slide my relay assembly up in with the wires and it fit perfectly and shouldn't slide out of place unless I roll the car. If that happens I promise not to worry if they slide out or not. Now I snaked the wires through a channel that runs from the driver side above where the cabin filter is and they ran out right by the ledge I put the relays on. Now it is very hard to work under the dash of a Fortwo. Even with the seats clear back the seat track hits me in the ribs and the lip the weatherstripping sits on at the door digs on your back. If you lay your back on a pillow there's no room to work your arms. So I either kneel outside the car on a pillow or lay acrossed the seat of the opposite side I'm trying to work on and lay on my head. Just be sure you remove the ignition key so your body weight doesn't break it off. It's no easy feat for an old man with a hip replacement to do it, but there's no other way. I used a straightened coat hanger with the wires taped to it to snake the wire from driver side to passenger side. A fish tape is just too large. But here's my hiding spot. I took this picture from the passenger seat looking to the 12 volt cigarette lighter plug.



Now as far as finding power from the fuse box (SAM) there is a row of power points down the edge and there are 9 of them. They are actually on 2 groups. Group 1 is power all the time and group 2 is switched power that is only on when the ignition is on. Now you know the Smart ignition only has off, on and start. There is no accesory connection. The factory lowline radio will play without the key being on for like 15 or 20 minutes then it shuts off unless you're there to hit the power button again to keep it playing. I don't know about the highline NAV radio. But I know of you add an aftermarket radio as I did I had no choice but to hook it up to powered all the time because I listen to it alot as I work on the car and I couldn't leave the switch in the on position with it not running because it's not good for the electronics. fuel pump etc,... You can run the battery down quickly. So here is the SAM and you'll see the row of power terminals down the left hand edge.




Now here is a breakdown of those terminals so you can see which ones are switched and which ones are on all the time. Probably some of them have been used from the factory or from other add ons, so you probably won't have them all available.



Here is the legend that corresponds with the pictures.



Now to use these power terminals, what I do is use a blade fuse:



And plug one side of the fuse into the SAM/fuse box power terminal. Then for the other blade of the fuse that protrudes over the edge I use a blade connector on that terminal and crimp a wire to it and use that wire.



I have never had one come loose and fall out of the SAM. Another alterntive I like to use instead of a fuse is a circuit breaker sized to the circuit. If there is a short the circuit breaker will kick and then after it cools inside it will reconnect. I must say that a circuit breaker is risky to use on the SAM becaue it is fairly fragile and if you did get a short and the circuit breaker kept tripping and resetting from a short it may cause damage to the SAM, so use them at your own risk and don't oversize the rating on amps for your circuit draw. Installation for the circuit breaker is the same as for a blade fuse.



So I still have to tackle the 2 lit up led's. It's probably just fantom power like when you put LED's in your dome light and you see it glow, but can't say for sure until I troubleshoot it. I know the dash light LED's on the button bank work as before. So I will do some more investigating and report back. DCO

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post #3 of 43 (permalink) Old 01-03-2017, 03:17 AM
 
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There are rear fogs available in other countries! I've got to figure out how to get that....
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post #4 of 43 (permalink) Old 01-03-2017, 04:35 AM
 
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Thanks for the great detail!
I'm going to use one of the buttons for the 1/2 speed fan setting in my ED.
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post #5 of 43 (permalink) Old 01-03-2017, 11:26 AM Thread Starter
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JZ if you've ever changed one of your tailight bulbs, you know there is an extra "3rd socket" for a bulb in the middle of the other two. That's for the rear fog light, so the wiring is in place, but I don't know if the tailight lense is somehow different in that there might be a focused or reflected surface on the inside of it to highlight that bulb if you know what I mean.
I've already done a version of the rear fog light and I don't know if it's legal to do here in the United States, but I did it anyway. I bought one of these and wired it in with my fog lamps so this it does it's thing only when I turn on the fog lights. And what's $2. But it will be much more if I get a ticket finding out ! But I want to be seen so nobody runs over me. I have it angled down close to the ground so it only shines to maybe 15 or 20 feet behind me, but if someone pulls in close behind me they'll get a laser pattern on their hood! It really shows up in fog.

Car Auto Vehicle LED Laser Fog Light Anti-Collision Taillight Brake Warning Lamp

It's very tiny, about the same diameter as a pack of rolaids and maybe an inch long. I'll take a picture of it later today and post it mounted on my tailgate. The only drawback to this light (LED) is that the tiny power cord has a black box right in the middle of the length of the cord, so to keep the wire hole tiny I had to cut the cord and run it through the hole and then splice the box back on it inside the tailgate. DCO
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post #6 of 43 (permalink) Old 01-03-2017, 01:16 PM
 
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I looked over the many many many different button banks on EPC in the middle of the night last night, as well as the lamps and associated stuff in the back area, and kind of gave up. I couldn't find the appropriate button bank, and I couldn't figure out the diagram for the lamps. Mercedes has had rear fog lights for some time, so I would hope they are legal. Actually researching front fog lights, I found that there may be a significant importance in rear fog lights vs. questionable utility of the front ones! Great idea!

So far I've only had to replace a burned out CHMSL bulb. Huge deposits on the bottom of the bulb, probably not getting hot enough for the halogen cycle to work. I requested advice on the Candlepowerforums and got a recommendation for LL bulb. I'm now looking at possibly getting the Brabus LED replacement A 451 906 49 00 if I can find a decent price...


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I have a 453 Proxy and it came with rear fog lights. On the light stock the inner part has a SPRING loaded switch that you click UP to turn on the front fog lights. To turn off the fogs click it UP again. Using the same switch click it DOWN. The rear fog lights come on. Click it DOWN again to turn off the rear fog lights. This only works when the LOW beam head lights are on. It must be legal as the smart came with this.
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post #8 of 43 (permalink) Old 01-03-2017, 01:32 PM
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Rear fogs have been legal in the US for decades.
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Originally Posted by Worker Not View Post
I have a 453 Proxy and it came with rear fog lights. On the light stock the inner part has a SPRING loaded switch that you click UP to turn on the front fog lights. To turn off the fogs click it UP again. Using the same switch click it DOWN. The rear fog lights come on. Click it DOWN again to turn off the rear fog lights. This only works when the LOW beam head lights are on. It must be legal as the smart came with this.


Try them with just the parking lights on. The OE front fogs on my 451, rears not included/available, will come on without the low beams.

Going to have to check on that open bulb socket! Thank you so much DCO!


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post #10 of 43 (permalink) Old 01-03-2017, 02:52 PM
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The tail lamp lenses are different on the Euro market & most of the rest of the world 451 smart cars. I believe they have 1 back-up light on one side & the rear fog light on the other side.
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