Heated seat wiring and control

[Ross Dunn 2]

I have two smart cars that I have added stock Smart car heated seats to.Of course these cars have none of the smart car wiring for heated seats. I have wired up a fused switch to turn them on and it works fine but the seat gets hot. My problem is how to have a reduced heat setting. I first thought I would separate the backs and seat heaters and do a series/ parallel wiring switch and relay like many aftermarket systems use. You have the heaters in parrallel for high heat and series for low heat. I can't do this however because the heater ressistance is too low, about 2 ohms. I think that I need a Pulse Width Modulate system. Can anyone help me with locating a controler for these heaters? Also does anyone know how Smart Car does it and has wiring diagams? If I got all the wiring ,switches and relays from a wrecked car and installed them would the SAM alow them to work?

Thanks

Ross

[CANMAN 23]

Pretty sure the SAM doesn't have any TAN code for heated seats, once you install the parts it should work.

There are 2 black relays next to the yellow fog light relay at the back of the plastic shell the SAM mounts into, that power the seats.

(Back when you are looking at the SAM from the drivers footwell)

And of course the switches on the centre console.

Did you check to see if there is a thermistor (sensor) in the seats to cycle the heaters on and off?

N11-3 pin 4 and N11-11 pin R9 are involved in the control of the seats.

Here is about the only thing you can get for a wiring diagram.

Canman

http://www.fq101.co.uk/how-to-guides/fortwo-450/electrical/251-sam-wiring.html#topofthepage

[Bessy 16]

The terminals I see from the above link seem to just feed power to heated seat module, looks like you might need a control module from the donor car as well. Factory wiring diagram would be helpful here. Dmoonan has access I think, I only have access to 451 wiring as I use Mitchell ProDemand and it's American.

From Prodemand on a 2008 Passion

The heated seats control unit controls the actuation of the left seat heated cushion (R13/1) and the right seat heated cushion (R13/3). The heat-up time is map-controlled and dependent on the interior temperature and the request from the left seat heater switch (S6/1s3) and the right seat heater switch (S6/1s4).

The interior temperature is determined by the heated seats control unit via an integrated sensor.

Control unit located above acelerator pedal

Edited October 28, 2014 by Bessy

[Bessy 16]

Again 2008 Passion but gives you an idea.

[Ross Dunn 2]

Thanks for your responses. There are no sensors in these 450 seats, just heaters and side airbags. I suspect that the 451 seats are different although there may be a temp sensor in the controls.

[tolsen 630]

Evolution has a guide on how to retrofit seat heating. Note that he never completed the installation. Now is your chance to be remembered for posterity by providing Evolution with the photos he require to complete his guide.

http://www.evilution.co.uk/index.php?menu=Electrical&mod=349

Edited October 30, 2014 by tolsen

[dmoonen 54]

I personally just bought a kit on eBay for less then a hundred bucks and bought one so that the switches match the cars theme so they don't stick out. Installed four heating pads per seat (2 lower and 2 along the back) and installed the switches on the face of the useless drawer under the radio. The wires and connections are all in the drawer.

The switches are high low and off settings.

Edited October 29, 2014 by dmoonen

[Ross Dunn 2]

I too bought an aftermarket kit for the switches and relays. I have good passion seats with factory heaters in them. I didn't want to pull them apart and install the aftermarket heaters when they already had factory heaters. I would if they didn't have heaters in them. I found that I couldn't use the switches and relays for the reasons already given. I will save the aftermarket heaters for when I recover the pure seats. I am almost certain that the stock system uses a pulse width (on/off, on/off) system and I will try to find the stock relays, switches and wires from a wrecked car. If anyone has a wiring diagram for the seat heater system for a 450 that would help.

[tolsen 630]

We have already pointed you towards Evilution. His diagrams may not be perfect but are the best available at this time. You can always contact him if something is unclear.

[Ross Dunn 2]

Evilutions diagrams are no help. I was hoping for an OEM wiring diagram. I guess it will have to wait till I can crack the WIS.

[Heilanpiper 0]

On 10/27/2014 at 8:46 PM, Ross Dunn said:

I have two smart cars that I have added stock Smart car heated seats to.Of course these cars have none of the smart car wiring for heated seats. I have wired up a fused switch to turn them on and it works fine but the seat gets hot. My problem is how to have a reduced heat setting. I first thought I would separate the backs and seat heaters and do a series/ parallel wiring switch and relay like many aftermarket systems use. You have the heaters in parrallel for high heat and series for low heat. I can't do this however because the heater ressistance is too low, about 2 ohms. I think that I need a Pulse Width Modulate system. Can anyone help me with locating a controler for these heaters? Also does anyone know how Smart Car does it and has wiring diagams? If I got all the wiring ,switches and relays from a wrecked car and installed them would the SAM alow them to work?

Thanks

Ross

 

Im pretty sure you need the two relay and matching panel on the end of the SAM. Together with wiring and Safety Island, it will work. I too am interested in retrofitting heated seats. Know where I can get a set up?

 

Cheers,

 

Victoria Chan-Ross (heilanpiper)

[Wild! 118]

If you want to keep it all oem your best route find junker of the same year with heated seats and take it all out from there including the main wire harness so can use all the same colour coded wires with proper gauge thickness to tie into your wire harness. What i did was a little more complicated, I have an 05 and put in 06 heated seats, I had to trace all the wires between both cars to make sure I got it right, there were some changes made in the sam fuse lay out between the 05 and 06. Thats not all the interior seats were different, that means I had to take the seats apart and swap the material. But if your not picky in that department that will save some time. The safety island and it's wire harness, the 2 relays and there sockets, and some add on fuses by the sam you are going to need beside the main wire harness. All in all this isn't as bad as it sounds.