I've done this to a couple of my
bikes and it's nice to be able to fine-tune the heated grips
to just the right heat level for the weather you're riding
in. What I use is a 12 volt 8 amp PWM (pulse width
modulator) "LED Dimmer" that can be had on eBay for about
$3 shipped. (Search for "12V Led Dimmer")
When you take the box apart
you'll find that the potentiometer under the knob is
separate from the PWM printed circuit board. What I did was
lengthen those wires so that I could install the
potentiometer and knob in the dash pad and hid the rest of
it in the fairing. I also coated the potentiometer in
five minute epoxy to waterproof it. I
installed a 3mm 12V LED, wired to the output, right
above the control knob for visual verification that the
heated grips are getting power and to make it easier to find
the knob at night.
Heated Grips: The factory main wiring harness for
K bikes has a connector for heated grips. It is a "T"
connector which has short leads and can be found under the
tank on the left side about two thirds of the way back. It
has two wires. The green/black wire is switched power from
Fuse 1. The brown wire is a ground. Use the green/black wire
as the positive input and the black wires from the old white
connector as the positive
output to the heated grips.
Heated Grips: (More info on Symtec grips
here.) Get the positive input power from
the OEM heated grips connector described in the prior
paragraph. This is a fused, switched power source.
(Fuse 1) Use
the white wires from the heating elements as the positive
output from the PWM. Ground the red wires. (You could try
running both the white and blue wires to the positive output
but you may run the risk of getting too much heat and
melting the plastic throttle tube.)
On my K1100RS I drilled a hole in
the dash pad and installed the potentiometer and knob.
On my K1100LT I used a smaller
PWM that I was able to build into the back of a switch
blank. Since the bike is green, I used a green LED.
Having gotten spoiled by having
variable heated grips on my K1100s, I decided my K75 needed
them too. I built a hybrid of the two prior designs where I
took the potentiometer from one of the PWM controllers at
the top of the page and installed it in a BMW switch blank.
I had to cut down the sides of the switch blank a bit to get
the potentiometer to fit. When I was finished, I
wrapped some electrical tape around it.
Since I planned to put it under
the tank, I put the circuit board in a 2 3/4" x 1 5/8" x
7/8" project box that takes up much less room.
Here's the finished product,
ready to be installed.
One of the nice parts of having
an LED hooked up to the output near the knob is that it
allows you to easily bench test it with a 12V battery before
installing it. (If you bench test it make sure that the
output wires that will attach to the heated are grips are
not touching each other,)
My first two variable heated grip
projects were on bikes that had BMW heated grips from the
factory. My K75 has Symtec heated grip elements. Each
side has two heating elements, one for the high setting and
one for the low setting. I hooked both elements up on each
side to the output from the PWM so now I can get my grips as
hot (or cool) as I want.
The BMW part number for a switch
blank is 32711459318 - about $2.
By the way, if you're not into
doing projects like this but still want variable heated
grips then you can plop down $70 for a Heat-Troller from
Warm-n-Safe to get variable heated grips.
© 2013 Drake Smith - Please do
not use or reproduce this elsewhere. Feel free to link
to it though.