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So you say your heated seats don't get hot enough?

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118K views 184 replies 91 participants last post by  Red Wing One  
#1 ·
First off, let me say that if you are satisfied with the way your heated seats work, LEAVE THEM ALONE and please SKIP THIS THREAD.

WARNING: DO NOT ATTEMPT IF YOU ARE ELECTRICALLY CHALLANGED. CUTTING INTO YOUR BIKES WIRE HARNESS CAN RESULT IN BAD THINGS IF YOU AREN'T 100% CERTAIN OF WHAT YOU ARE DOING.

IF YOU DO THIS MODIFICATION IT IS AT YOUR OWN RISK


However, if you are one of those that feels your seats don't get hot enough, I may have a way to help you, but it will require you make a modification to the wire harness.

Before I get into the actual mod, let me tell you the results of my measurements. I took a cold seat at about 55 degrees and measured the thermistor values in it. They are all around 67K to 69K ohms. I then put it back on the bike and ran the seat heater on high and remeasured them. They were around 35K ohms after few minutes. Unfortunatly, it doesn't get that cold here in Texas, so I was unable to measure the thermistors at any temp lower than about 55 degrees, but I suspect the thermistors would probably rise another 20K ohms or more when really cold soaked around freezing.

If you look close at the circuit for the front seat, you will see it has two thermistors connected to a common ground. So to raise the seat temperature, all you have to do is add resistance, and the best place to do this is on the common ground line.

I began with 10K ohms, then tried 20K ohms and 30K ohms. 30K ohms was WAY TOO MUCH, and got the seats too hot. I measured seat temps both with an infarred temp gun, and by the seat of my pants, so to speak. What I thought felt about right in the garage was 20K ohms, so I put that in and went for a ride. I found that with a 20K ohm resistor in, even on the lowest setting, I couldn't get the seat temp low enough for it to be comfortable in 55 degree weather. So it seems like the trick is finding the very lowest value of resistor you can that will still let you use the low setting when you want, but slightly increasing the heat out of the seat on all settings. I went back and put in the 10K resistor and went for a ride. For me, this is perfect. It has about the same effect as turning up the dial one notch at all settings, and I couldn't stand having it all the way on high at the current ambient temp of about 55 degrees.

Also, be aware, there are TWO green/black ground wires in the harness for the grounds to the thermistors. One is for the rear passengar elements and one is for the riders. You have to make sure you cut the right one. On the 2009, it is in the center position of the connector. If you are unsure, leave it alone.

Also, be aware that some of the color codes have on the seat heater wires have change since 2006, but the grounds are still green with a black stripe.

And please, whatever you do, don't use a resistor larger than 20K ohms. You'll be sorry if you do.

Also, be warned that I have not tested this mod in colder temps. It is very possible that the seats could end up getting TOO HOT when the temp drops further. This is another reason why I suggest you use the smallest value resistance possible.

Schematic
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This is the common ground for the riders thermistor circuit
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OH MY GOD!!!
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Resistor installed (I later changed this 20K to a 10K)
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All covered up with heat shrink
Image
 
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#2 ·
Thanks Fred for the info. On my 08 the heater on high is just noticeable on high so this is going to be a big help. I haven't looked yet ( will be with all my other winter projects) but I suspect that the 08 wiring will be the same as your 09
 
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#4 ·
The way this works is that it increases the resistance of the thermistor value that the control unit reads to determine how much current to apply to the seat elements. By increasing the amount of resistance, it makes the controller think that the seat is colder than it really is. So all you do is add resistance in series with the thermistor. This basically shifts the entire heating curve up higher on all settings. The trick is to only shift it enough to make it warmer, but not so much that you can't run it on the lowest setting on a mildly cool day with it not getting too hot. This is why I choose 10K ohms, as it changes it enough to make it warmer, but not so much that you can't turn it down and run it on low on a 58 degree day and just get a very low level of heat. Also be aware that increasing the resistor means the controller is putting more current into the seat and making your alternator and electrical system work harder. This is another reason to use the lowest value resistor you can. And if you use too large of a resistor, you also run the chance of burning out the heater element or maybe even melting your seat or causing a fire.

And in case you are worried about the wattage of the resistor, I put an ammeter on it, and it hardly even registered. There is very little current that goes through the thermistor circuit, it is just enough to read the value of it. A 1/4 watt resistor is plenty large enough.

By the way, if you want to turn up the heat on the passengers seat too, just add the same size resistor to the other green and black striped ground wire.
 
#5 ·
I can see it now...someone will make this mod with bad eyesight and put a 100K resistor inline instead of a 10K resistor and being riding down the highway with their seat on fire! :shock:

Be sure you know the correct color code in case you pull one out of your stash. If you're not sure, go to Radio Shack and buy one or look up the correct color code on the internet.
 
#6 ·
Bartman said:
I can see it now...someone will make this mod with bad eyesight and put a 100K resistor inline instead of a 10K resistor and being riding down the highway with their seat on fire! :shock:

Be sure you know the correct color code in case you pull one out of your stash. If you're not sure, go to Radio Shack and buy one or look up the correct color code on the internet.
Click to expand...
If you smell smoke coming up from between your legs then you know you messed up.

:crew:
 
#8 ·
Bartman said:
I can see it now...someone will make this mod with bad eyesight and put a 100K resistor inline instead of a 10K resistor and being riding down the highway with their seat on fire! :shock:

Be sure you know the correct color code in case you pull one out of your stash. If you're not sure, go to Radio Shack and buy one or look up the correct color code on the internet.
Click to expand...
Image
 
#12 ·
Increased heat

I live in central Illinois with a 2007 Trike. I can assure you, that it gets cold enough here (32 this morning with 1" of snow) the seat gets warm enough that I have to turn it down. My problem is the handlebar grips with the Kuryakyn grips. I do get heat, but would like to have more. Fred, do you see a way to increase the heat in them without creating too much heat on the inside of the grips?

Thanks, Dick
 
#13 ·
Gwingbuzz said:
Fred, Great info. You are not responsible for this info,but is the harness the same on the 06 Wing? Are the color codes the same but in different locations? Thanks Buzz
Click to expand...
The color codes on the 2006 schematic I have show that the wire colors on the seat side of the connector have changed some, but the color code on the BIKE side of the connector for the thermistor ground circuit is still shown to be GREEN with a BLACK STRIPE.

If you are unsure, pull up the page in your manual that shows this schematic, and follow the RIDERS thermistors over to the COMMON GROUND that they share and check the color code of it.

However, be warned, I have not done this modification on any model year other than the 2009. You might want to put an ohmeter on the thermistors and see what they measure to make sure they haven't been changed. I got about 67K ohms at 55 degrees. They should be somewhere close to that.





Image
 
#15 ·
dgamage said:
I live in central Illinois with a 2007 Trike. I can assure you, that it gets cold enough here (32 this morning with 1" of snow) the seat gets warm enough that I have to turn it down. My problem is the handlebar grips with the Kuryakyn grips. I do get heat, but would like to have more. Fred, do you see a way to increase the heat in them without creating too much heat on the inside of the grips?

Thanks, Dick
Click to expand...
There are no thermistors in the grips, so this trick won't work with the heated grips.
 
#17 ·
itsapitty said:
Fred, could you use a poteniometer to vary the resistance to simulate different temp conditions?
Click to expand...
Yes if it was the right size, but I wouldn't advise it. The danger would be that if the POT's wiper arm opened up (as they frequently do) the seat heater might go into a thermal runaway condition. I don't know if the system shuts itself down if it senses an open on the thermistors or not, but if it doesn't auto shut down, and the thermistor circuit is open, the heater would run wide open with no regulation.

Personally, I think you are better off just putting in a standard 10K ohm resistor and using the dial adjuster on the bike to control the heat level.

It is also worth mentioning, that this modification will probably be of more use to folks who ride in milder temps, where the seat heater doesn't come on as much, than it will for folks in colder climates. When the seats are really cold (say below 35 degrees) there probably is no need for this modification.
 
#19 ·
Fred H. said:
It is also worth mentioning, that this modification will probably be of more use to folks who ride in milder temps, where the seat heater doesn't come on as much, than it will for folks in colder climates. When the seats are really cold (say below 35 degrees) there probably is no need for this modification.
Click to expand...
:agree:
 
#22 ·
Seat heat

Fred,
Are you doing the bike plug or the seat plug. I guess I'm asking are you doing this at the plug that the seat plugs into, or are you doing this on the plug that is on the seat itself? I know it's confusing, because I'm confused..............
 
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#23 ·
Seat Heat Mod

wingnut6670 said:
Fred,
Are you doing the bike plug or the seat plug. I guess I'm asking are you doing this at the plug that the seat plugs into, or are you doing this on the plug that is on the seat itself? I know it's confusing, because I'm confused..............
Click to expand...
From the pics he posted, the bike side of the harness.
 
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#24 ·
wingnut6670 said:
Fred,
Are you doing the bike plug or the seat plug. I guess I'm asking are you doing this at the plug that the seat plugs into, or are you doing this on the plug that is on the seat itself? I know it's confusing, because I'm confused..............
Click to expand...
Read post number 14:

Fred H. said:
Here is the 2006 schematic I have. Note that on the BIKE side of the connector, the common ground is still shown as GREEN with a BLACK STRIPE.
Click to expand...
I'd recommend reading all of Fred's posts thoroughly. You don't want any doubt if/when you cut that wire. ;)
 
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