Post image for Wiring a Gerbing’s Permanent Dual Temp Controller to SPI Grip Heaters

As I mentioned yesterday, the low circuit on my heated grips stopped working when the ceramic resistor in the circuit gave up the ghost. Some commenters have mentioned using a bracket or silicone to secure the resistor from vibration. As a clarification, yes, I did have the resistor mounted in a bracket, but I probably could have done a better job of wire management to prevent the connections from vibrating off. I also want to point out that the space behind the headlight bucket on a naked SV650 doesn’t leave much room for anything, much less a complicated bracket/wire guide setup. And there’s another problem entirely: sometimes the low setting is too low, but the high setting is too hot for comfort.

The best solution is to use a temperature controller. I chose the Gerbing Permanent Dual Temp Controller kit, which was obtained for $120 at a local shop. Clocking in at 4 times the price of the heated grip kit itself, it’s not much of a stretch to say I have high expectations for this controller.

Gerbing Permanent Dual Temp Controller

Gerbing Permanent Dual Temp Controller (opened box)

The box contained the following items:

  • temperature controller unit with wires to two accessory plugs (coax), wires to the control knobs, negative battery terminal, positive battery terminal (fused)
  • two control knobs with LED indicator lights (connected separately using S-video connectors!)
  • two 18″ power wires, one end male coax and the other end female coax
  • spare control knob

After removing the headlight and turn signal mount and surveying the myriad of wires running hither and yon between the grips, switch, and back toward the battery compartment, I had a moment of despair at ever being able to figure out how to get this thing wired together. Then, I took a deep breath and looked at the wiring diagrams that came with the grip kit and the temperature controller. Here’s what I came up with:

Gerbing Temp Controller to heated grips wiring diagram

The wiring is actually much simpler than you’d think, thanks to the temperature controller. All I needed to keep from the original heated grip kit were the heater elements and their attached wires. Everything else — the switch, high/low wires, and resistor — could be discarded.

The goal is to connect the heater elements to the accessory #1 plug. Take one wire from each heater element and solder them together. On the original kit, this wire went all the way back to the ground side of my distribution block. Instead, “ground” is now the negative wire leading to a male coax power plug. Next, take the remaining wire from each heater element, and solder those together. This connects to the positive wire leading to the same coax power plug. Where’d I get the male coax plug? I cut one of the 18″ wires that came with the controller in half.

You may be wondering why I didn’t just cut the accessory plug and splice the heater wires directly to that. Unfortunately, cutting any of the controller wires voids the 3 year warranty. By cutting the “extra” wire and using it to connect to the controller, I figured I could keep the warranty valid and accessory plugs intact should I ever decide to hook a different accessory up instead of the grips.

Now that I had the heater elements wired up to a male coax plug, the next step was finding a location for the controller box that allowed the control knob wires to reach the handlebars while also letting the shorter battery wires reach the battery and accessory wires to stow someplace under the seat. The only place that worked — and it was a tight fit — was sticking the controller box inside the frame just to the aft of the airbox under the gas tank. Sometime during the search the batteries on my camera crapped out so I only have a picture of things after the fact. The ziptie is where the controller box is tucked against the frame.

ghetto ziptie

The last step was running the wires.

  • two wires from the heater grip elements, terminated with male coax power plug -> routed back to under the seat
  • two wires from controller box, terminated with S-video connectors -> routed up to the headlight
  • two wires from controller box, for battery connections -> routed to battery
  • two wires from controller box, accessory plugs -> routed back under the seat

The downside to not being able to cut any wires connected to the controller was not being able to wire to my distribution block and relay, since the controller comes with fused battery wires and ring terminals. Eventually, I’d like to come up with a clean (i.e. non-destructive) way to connect the ring terminals to the distribution block.

I also wonder about the use of the very chunky S-video type connectors between the actual control knob units and controller box. I’ll have more about this in a later post.

My final gripe is very minor: the control knobs are nice and big, but they turn so smoothly it’s hard to tell if I’m doing anything through thick gloves. The LED indicator lights do flash at different intervals to indicate the current setting, but a few “clicks” or detents would provide tactile feedback.

Other than that, the controller works great. The grips do take a little longer to heat up, but being able to dial-in a happy medium is worth it! One last thing, if you’re wondering how I mounted the control knobs on a naked bike… stick around, because part two of this write-up will cover exactly that.

And here’s part two: HOWTO: Make a Dirt Cheap Handlebar Switch Mount

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