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King of Smart Gadgetry
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Do any of you have the ELM 327 bluetooth adapter for use in your Smart? If so, do you leave it plugged in all the time or has someone figured out a way power it down with a switch? I've been fighting the "battery drain" problem and I still don't have it completely remedied yet. I just hate the fact of having to unplug the 327 everynight night and remember to plug it back it every day. I thought about putting a switch on fuse number 12 to kill the On board diagnostics, but that fuse also controls turn signal lamps and the transmission control module, so I would have to remember to switch it back on before starting the car and that's as bad as having to remember to plug it back in. I guess I could put it on a relay that is ignition switch controlled, but the SAM fires up the "boot up" pretty quickly before you can get the car to start. So I don't know if using the relay would energize that fuse in time before the system finished boot up. If it didn't there would be a few error codes and a check engine light. So I don't really want to do that. Going to spend today further investigating the battery drain issue that I thought I had fixed. Will report back on that later. DCO
 

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I've gone 3 weeks with one plugged into my Smart and still able to start the car without issue.
I don't remember if it is the ELM or another One of the BT adapters, I've found have an auto-off feature whether it's timer or battery level related I don't know.

Judging by the technical documents the draw of the ELM327 IC and a typical bluetooth IC would the the equivalent of running 1-2 LEDs at all times.

You can also try leaving it in all night and in the morning before starting the car feel how warm it is. Heat = energy used Then judge for yourself if you think it maybe too warm for a standby mode. Mine is cool to the touch.
 

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Do any of you have the ELM 327 bluetooth adapter for use in your Smart? If so, do you leave it plugged in all the time or has someone figured out a way power it down with a switch? I've been fighting the "battery drain" problem and I still don't have it completely remedied yet. I just hate the fact of having to unplug the 327 everynight night and remember to plug it back it every day. I thought about putting a switch on fuse number 12 to kill the On board diagnostics, but that fuse also controls turn signal lamps and the transmission control module, so I would have to remember to switch it back on before starting the car and that's as bad as having to remember to plug it back in. I guess I could put it on a relay that is ignition switch controlled, but the SAM fires up the "boot up" pretty quickly before you can get the car to start. So I don't know if using the relay would energize that fuse in time before the system finished boot up. If it didn't there would be a few error codes and a check engine light. So I don't really want to do that. Going to spend today further investigating the battery drain issue that I thought I had fixed. Will report back on that later. DCO
I thought the OBD II plug was always 'hot' and I'd be a bit hesitant to start messing with the wiring to that socket to kill power to it when the car is off. Reason being it might create other issues with other systems in the car such as keyless entry and security system if equipped.

That ELM unit sounds interesting though, is the one you have the translucent blue version that I see on eBay?
 

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When I shut off the key, my ScangaugeII goes off, but that may be a function of the gauge reading the charging voltage. had a y adapter for power outlet that would shut off if line voltage dropped below 12.8 volts.
 

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King of Smart Gadgetry
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Discussion Starter #5
I thought the OBD II plug was always 'hot' and I'd be a bit hesitant to start messing with the wiring to that socket to kill power to it when the car is off. Reason being it might create other issues with other systems in the car such as keyless entry and security system if equipped.

That ELM unit sounds interesting though, is the one you have the translucent blue version that I see on eBay?
Yes the Elm unit I bought from E-bay is one of the translucent blue ones. DCO
 

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For what it's worth, my ELM unit has been plugged in for months and hasn't affected battery. I'm in eastern Canada, average temps this time of year around 5C.

The unit has been great when paired with the "Piston" app for Android.

Sent from my MI 5s Plus using Tapatalk
 

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Discussion Starter #8
For just a point of reference on the transluscent blue Elm327 ODBII adapter. It doesn't go to sleep ! My smart has sat downstairs in the garage untouched for a couple of days. I am in my living room and I just turned on my bluetooth on my laptop to fire up my bluetooth speakers. As my laptop bluetooth scanned it found OBDII adapter. "Would I like to connect?". So I am sure that it doesn't go to sleep after a peroid of inactivity. DCO
 

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For just a point of reference on the transluscent blue Elm327 ODBII adapter. It doesn't go to sleep ! My smart has sat downstairs in the garage untouched for a couple of days. I am in my living room and I just turned on my bluetooth on my laptop to fire up my bluetooth speakers. As my laptop bluetooth scanned it found OBDII adapter. "Would I like to connect?". So I am sure that it doesn't go to sleep after a peroid of inactivity. DCO
Interesting, do you think this is somehow connected to your battery draining issues? Not the Elm327 per se but perhaps something else that is keeping your electrical system 'live' when the key is off?

This goes back to my comment about solar chargers when I discovered that hooking one up somehow caused our Dodge truck to think that the key was in the acc position. Problem with that was once the sun went down the battery would discharge and the solar charger obviously didn't have enough power to undo this process once the sun came back out resulting in a dead battery.

So my question would be is the car plugged into a battery maintainer? And if so could this be the same type of symptom my Dodge had where power in the battery circuit caused the car to think it was 'on'? Or perhaps something else in the smart is causing the car to be 'live' all the time such as an aftermarket radio or amplifier or perhaps alarm system?
 

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Just saw this thread just this morning for the first time. DCO, you've got so many "surprise" electrical devices connected to Max, I'm not sure if we can keep up!!!! The only time I've even seen something connected to the OBDII port on mine was when Huronlad tried to help me turn on the DRL function....

Looking forward to another interesting find/solution!!!
 

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Discussion Starter #11
Interesting, do you think this is somehow connected to your battery draining issues? Not the Elm327 per se but perhaps something else that is keeping your electrical system 'live' when the key is off?

This goes back to my comment about solar chargers when I discovered that hooking one up somehow caused our Dodge truck to think that the key was in the acc position. Problem with that was once the sun went down the battery would discharge and the solar charger obviously didn't have enough power to undo this process once the sun came back out resulting in a dead battery.

So my question would be is the car plugged into a battery maintainer? And if so could this be the same type of symptom my Dodge had where power in the battery circuit caused the car to think it was 'on'? Or perhaps something else in the smart is causing the car to be 'live' all the time such as an aftermarket radio or amplifier or perhaps alarm system?
I played the Moose Lodge tonight and I hauled my guitar (Les Paul) and my amp (Fender Mustang III) and took a shoulder bag with cords in it. I have to fold the passenger seat down and the guitar lays there and the amp in the cargo area. When I take my long keyboard (M-Audio pro-SX88) it's case just sits on the ledge of the dash and I can just close the tailgate. Talk about a perfect equipment hauler. It's like the car was custom designed to carry my band stuff and the dimensions fit to a tee. But I came out tonight to go home and I noticed the DVD player that was an option for my Atoto Mark 4 head unit was on. The light for the eject button was on and it had to be getting power from the Battery wire on the radio. So I ejected the DVD that was in the player and the light went out, so I presume it went to sleep.
Now for the radio the Battery wire goes to the fusebox to a terminal that powers it all the time. The Accessory wire goes to a fusebox terminal that is only hot when the key is turned on. So I tried rigging up a toggle switch from the radio battery wire to the radio accessory wire so that I could play the radio without turning on the key. But I found when I flipped the toggle switch on, the dash and everything came alive just as if I had turned on the key. So I'm thinking the only way out to fix this and still turn the radio on with the toggle switch is to put a diode on the accessory wire between the fuse box connect and where I spliced in the toggle switch on that wire. That way the diode will allow power to flow from the fuse box to energize the radio when the key is on. Then when the key isn't on and I use the toggle switch the diode won't let voltage backfeed through the accessory wire to energize the dash lights through the fusebox. I would be curious if the backfeeding to the igntion circuit would allow a person to start the Smart if I had a jumper switch connected to the starter solenoid? That would bypass the need for a key, but I figure the immobilizer wouldn't let the car start. But it was an interesting thought. So I hope I have the battery drain issue solved. I'm paranoid about leaving the car in the garage without plugging in the battery tender. When I do put it in the garage and I hook up the tender it is a red LED and after about 30 to 45 minutes the LED changes green which means the battery is fully charged. But I ran a socket connector out of the corner of the service flap up by the driver wiper. It sticks out in plain sight and looks bad, but it reminds me to plug in that tender just in case. The car starts well after 3 days, but hopefully when I get my other car back from my son I can let the Smart sit dormant for 2 or 3 weeks and I will see if he starts up. DCO
 

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I played the Moose Lodge tonight and I hauled my guitar (Les Paul) and my amp (Fender Mustang III) and took a shoulder bag with cords in it. I have to fold the passenger seat down and the guitar lays there and the amp in the cargo area. When I take my long keyboard (M-Audio pro-SX88) it's case just sits on the ledge of the dash and I can just close the tailgate. Talk about a perfect equipment hauler. It's like the car was custom designed to carry my band stuff and the dimensions fit to a tee. But I came out tonight to go home and I noticed the DVD player that was an option for my Atoto Mark 4 head unit was on. The light for the eject button was on and it had to be getting power from the Battery wire on the radio. So I ejected the DVD that was in the player and the light went out, so I presume it went to sleep.
Now for the radio the Battery wire goes to the fusebox to a terminal that powers it all the time. The Accessory wire goes to a fusebox terminal that is only hot when the key is turned on. So I tried rigging up a toggle switch from the radio battery wire to the radio accessory wire so that I could play the radio without turning on the key. But I found when I flipped the toggle switch on, the dash and everything came alive just as if I had turned on the key. So I'm thinking the only way out to fix this and still turn the radio on with the toggle switch is to put a diode on the accessory wire between the fuse box connect and where I spliced in the toggle switch on that wire. That way the diode will allow power to flow from the fuse box to energize the radio when the key is on. Then when the key isn't on and I use the toggle switch the diode won't let voltage backfeed through the accessory wire to energize the dash lights through the fusebox. I would be curious if the backfeeding to the igntion circuit would allow a person to start the Smart if I had a jumper switch connected to the starter solenoid? That would bypass the need for a key, but I figure the immobilizer wouldn't let the car start. But it was an interesting thought. So I hope I have the battery drain issue solved. I'm paranoid about leaving the car in the garage without plugging in the battery tender. When I do put it in the garage and I hook up the tender it is a red LED and after about 30 to 45 minutes the LED changes green which means the battery is fully charged. But I ran a socket connector out of the corner of the service flap up by the driver wiper. It sticks out in plain sight and looks bad, but it reminds me to plug in that tender just in case. The car starts well after 3 days, but hopefully when I get my other car back from my son I can let the Smart sit dormant for 2 or 3 weeks and I will see if he starts up. DCO
A quick thought about this, does your radio have a separate feed for the dash dimmer system? In other words is there a second 'hot' lead to that circuit so that when you dim the dash it dims the display on the radio? Is so that might be the source of the leak? Long shot though.

I wonder what it is with tenders causing cars to go 'live' it's odd since I use solar battery tenders on our Saturns and have no problems with them draining the battery. But put one on the Dodge, the exact same one's we use on the Saturns, T-Bird and Jeep and it goes dead after a few days. I put an AC tender on it and it's fine, well other than the radio comes on without a key. The Dodge is weird in that it's radio stays live after the key is removed for a minute or until a door is opened so it almost sounds like it has a capacitor in it that keeps it live until it's dumped. That I did not notice on my smart. Hope you can finally track down this problem!

Once we are done with winter I'm going to install my 2 way gear and I'm driving myself nuts trying to figure out a decent location for an antenna. Because it's a cabrio my options are really limited so it's looking like the tow bolt holes except that my cover being form fitting won't fit at that point or my mount will wind up punching a hole through the cover.

Best not tell the wife her Strat case and amp will fit in 'my' smart with the seat down! But good to know. :D
 

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Was thinking a bit more about the dash dimmer circuit. On my Saturn I disabled it on my aftermarket CD/DVD unit because it would dim the display when I turned on the headlights. Wasn't that bad at night but if I drove with my lights on during the day it dimmed the display enough that it was impossible to see. I remember it being a separate lead into the wiring harness when I did the installation. Same with the aftermarket radio I installed in the Jeep and in my wife's Saturn. Come to think of it I stopped hooking up that dimmer wire in our cars though I think on one I just wired it into the 'hot' lead that the main power lead from the radio was wired into and the more I think of it I suspect I did that with all the other radios so that it stayed bright all the time. So if you put that lead on the same switched power lead as the radio it might solve the problem. The dimmer is a rheostat come to think of it so it would be switched via the key. On the Dodge I swapped in a higher end factory Nav system so it used the same wiring.....and it has the draining problem with the solar tender.
 

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Discussion Starter #14
When I installed my Atoto radio the wire for the dimming of the radio was uncorprated in the Metra wiring harness I bought that matched the Fortwo. But as usual the Fortwo is a horse of a different color and Smart does alot of things different. The dash illumination is lighted with LED's and they are a lower voltage than a standard T10 automotive bulb. Can bus controls the lighting and the ciip that controls the dash lights wouldn't supply the 12 volts that my radio needed to dim itself when I turned on the headlights. I ended up cutting the wire out of the Metra connector and I ran a wire from the parking light in the headlight assembly clear inside the car and spliced it to the illumination wire on the radio. That way the radio got the full 12 volts and when I turned on the parking lights the radio dimmed as it should. If I would have applied 12 volts to the illiumination wire and had NOT disconnected it from the harness I would have undoubtedly blown out the chip that supplies low voltage to the dash cluster.
I learned the Can bus system early on. When I bought my Fortwo it did not have the dash pod clock or tach. I bought them used off from ebay. But when I got them they were missing the wire that connects them both to the dash cluster for them to work. So in my zeal to install them and my ignorance of Can Bus, I thought I would go ahead and hook up the clock. The clock had 3 wires coming from it so I surmized that there was a Hot wire for power to the clock, a ground wire for the clock, and a Illumination wire to light it up at night. I went to my work bench and got out my 12 volt power supply and in shooting 12 volts to the clock I ruined it. So I ended up buying another clock and it was from a 2005 Fortwo, so I had to make a change of 2 of the wires to make it work. But the pods run off of Can bus and they never recieve 12 volts, analog wiring does not apply to the Fortwo. Disconnect your battery for a few seconds and then reconnect it and you will hear your tach and clock spin up. So I learned the hard way that NOTHING is conventional on the Smart.
Try to find your switch that turns the dome lights on and off when you open or close the door. They are integrated into the door latch mechanism. When you flip a switch it doesn't necessarily mean you switched on or off 12 volts. You're sending a low voltage signal to the SAM to switch something on or off. So tread lightly whenever you add something to the Fortwo because it can cause problems. I have had many problems over my Android radio with the Smart, and Atoto has agreed to replace my radio with a newer version with better WiFi and less voltage drain, so I'm going to take the radio out again, but thank goodness it will be plug and play this time. DCO
 

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Relay to dimmer wire wouldn't work? (I like to follow the original design as much as possible to prevent strange results from coming about...)
 

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I learned the Can bus system early on. When I bought my Fortwo it did not have the dash pod clock or tach. I bought them used off from ebay. But when I got them they were missing the wire that connects them both to the dash cluster for them to work. So in my zeal to install them and my ignorance of Can Bus, I thought I would go ahead and hook up the clock. The clock had 3 wires coming from it so I surmized that there was a Hot wire for power to the clock, a ground wire for the clock, and a Illumination wire to light it up at night. I went to my work bench and got out my 12 volt power supply and in shooting 12 volts to the clock I ruined it. So I ended up buying another clock and it was from a 2005 Fortwo, so I had to make a change of 2 of the wires to make it work. But the pods run off of Can bus and they never recieve 12 volts, analog wiring does not apply to the Fortwo. Disconnect your battery for a few seconds and then reconnect it and you will hear your tach and clock spin up. So I learned the hard way that NOTHING is conventional on the Smart.
Try to find your switch that turns the dome lights on and off when you open or close the door. They are integrated into the door latch mechanism. When you flip a switch it doesn't necessarily mean you switched on or off 12 volts. You're sending a low voltage signal to the SAM to switch something on or off. So tread lightly whenever you add something to the Fortwo because it can cause problems. I have had many problems over my Android radio with the Smart, and Atoto has agreed to replace my radio with a newer version with better WiFi and less voltage drain, so I'm going to take the radio out again, but thank goodness it will be plug and play this time. DCO
The CAN bus has nothing to do with running the instruments or any other components. It is a high-speed communication link between major control modules. Instruments are typically operated by low-voltage stepper motors. In the case of the smart tach and clock pods, the clock is wired to the tach and the tach is networked to the SAM by way of the LIN bus. That is a Local Interior Network. This is not exclusive to the smart but is fairly common. Some vehicles may have as many as a dozen or more networks.
 

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Discussion Starter #17
The CAN bus has nothing to do with running the instruments or any other components. It is a high-speed communication link between major control modules. Instruments are typically operated by low-voltage stepper motors. In the case of the smart tach and clock pods, the clock is wired to the tach and the tach is networked to the SAM by way of the LIN bus. That is a Local Interior Network. This is not exclusive to the smart but is fairly common. Some vehicles may have as many as a dozen or more networks.
I started typing a reply to this and then I stopped and instead of defending what I said I will say this. When I fried my clock I knew I didn't understand the CanBus system. So here is a link to the Mercedes Benz CanBus explained. This is the article that I read to learn more about CanBus system and you can read it too and draw your own conclusions from it. I did. DCO

https://www.mbca.org/star-article/september-october-2012/modern-tech-concerning-can-bus
 

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I started typing a reply to this and then I stopped and instead of defending what I said I will say this. When I fried my clock I knew I didn't understand the CanBus system. So here is a link to the Mercedes Benz CanBus explained. This is the article that I read to learn more about CanBus system and you can read it too and draw your own conclusions from it. I did. DCO

https://www.mbca.org/star-article/september-october-2012/modern-tech-concerning-can-bus
I have read that info previously and it does not contradict anything I stated, other than I mistakenly wrote Local Interior Network instead of Local Interconnect Network. That article simply goes into greater detail. The CAN bus does not operate devices. The CAN bus just connects the modules so the module processor can tell a driver in the module to actuate a particular device. That is what I was getting at. We are probably only differing in semantics.
 

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Discussion Starter #19
Thanks RustedWrench for helping out with the CanBus thing. I want to get my facts straight and you have helped me understand it even better. I greatly appreciate your help. Hopefully others will benefit from this also. Keep your knowledge coming because I for one appreciate your input always ! DCO
 

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Look up for "OBD2 switch". There are cables with a simple switch. They work just like a lamp switch; turning it on or off. You only have to remember to turn it off everytime you leave the car, and turn it on whenever you want to use it.


A little question. Will all OBD2 bluetooth dongles work with Smart and will Torque app be able to show MPG with any OBD2 bluetooth dongle? If you got a second, any good samaritan could take a quick look at this search on Amazon Spain and gimme your insights. Thank you!!
 
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