Hard wiring Wet Okole seat heaters: '01-'04 Tacoma

This is my first post but I have been lurking on the site for months, benefiting from lots of great threads and info from other members. Hopefully I can pay some of that back with some helpful info for someone here. This will work for later models and frankly for any vehicle, but I post it here in the 1st gen forum because the diagram and pictures are specific to the console layout in my '03 Tacoma.

One thing I couldn't find on Tacoma World was an adequate description of how to straightforwardly "hard wire" my Wet Okole seat heaters into my electrical system. The seat covers are awesome, but the heater controllers are awkward and enormous. Worse, all the wires make an untidy jumble in the cab. And if, like me, you have both driver and passenger side heaters, the stock power plugs greedily take out both of your auxiliary power ports, which is an unacceptable (and -- as shown here -- unnecessary) sacrifice in my view.

So I searched high and low on other sites and finally got some useful inspiration and information from a Nissan-lover (gasp) at NC4X4. The description I found was helpful (props to OnlyOneDR) but far from complete, and it took quite a bit of trial and error to get it right. So I decided to write up a more complete description and make some wiring diagrams, both so that I could follow what I did later if needed and to provide some help to other like-minded lovers/haters of their Wet Okole seat heaters. I am just finishing everything off today so this thing will poop out over a series of posts in the next few days.

Realistically, you'll need a full day to complete this project, assuming you have all materials in hand and allowing for some head scratching and some beer slurping along the way. For those more experienced with electronics, it's probably more like a half day project.

All in, you'll need to sink somewhere between $40 and $70 into the switches, relays, fuse taps, fuses, wire, and wire connectors depending on where you buy everything, whether you buy things in bulk, and how much bargain hunting you are willing to do.

Let me know if you have questions.

 

Here is the wiring diagram. It includes detailed notes and guidelines on installation of each of the key components.

Again, it is specific to the '01-'04 Tacoma passenger compartment but can be applied with adaptation to any vehicle.

I include screen shots as teasers, but you can download the attached .pdf (at bottom of post) for a higher res version that will let you zoom in and see everything in detail. In later posts I will provide real-life images of completed components and a list of materials.

Important disclaimer: Use at your own risk. I accept no responsibility for any damage you might do to your vehicle, yourself or anything else in implementing all or any part of this modification.

 

Here are some images:

First is the WO controller with back cover off. I hooked the controller up to a test battery and used a multimeter to explore how voltages change at different pins as you change the switch on the front of the controller. This showed which pins I needed to solder to to bypass the switch.



Next is a close up of the controller.



Next is a view of the controller with the leads soldered on to the appropriate pins. (I accidentally nicked the insulation on the blue wire slightly so had to tape it up.) All it took was a $7 soldering iron, some rosin cored solder and a bit of exploring on youtube for how-to tips. I also bought a solder sucker ($6), in case I made a mistake, but I did not need it.

To make solid connections, I found that the following procedure worked pretty well:
* Plug in soldering iron
* Secure the controller to your work surface with tape or a clamp.
* Strip a tiny amount of insulation off the end of the wire
* Tin the wire (look it up on youtube if you do not know what this means)
* Use the soldering iron to heat up the pin
* By touching the solder to the pin and soldering iron, you can apply a tiny drop of fresh solder to the pin.
* Once the molten solder is in place, remove the soldering iron from the pin.
* Put down the solder and pick up the wire.
* Make the solder molten again with the iron and connect the wire to the pin.
* Remove the soldering iron from the pin and allow new connection to cool. (Done!)

In my wiring scheme, the colors correspond to different functions:
Red - always 12 V power.
Black - always ground (earth).
Yellow - bridge that completes pathway to ground when console switch is flipped to "High" setting. When engaged, this energizes high power pathway on circuit board.
Blue - bridge that completes pathway to ground when console switch is flipped to "Low" setting. When engaged, this energizes components needed for low setting on circuit board.

An aside: I am no electrical engineer, so I have no idea whether this is common on these kinds of controllers, but it seemed odd to me that the primary function of the stock WO switch is to complete the path to ground, rather than to complete the path to "power." On all toggle switches I am familiar with, including the rocker switches I bought for this project, the function is to complete the path to power. This difference is the reason why the relays need to be employed. OnlyOneDR's build, which inspired my efforts, uses relays, but I was hopeful that this was overkill and that I could dispense with them (because it adds significant complication and cost). But once I hooked up a multimeter to the board and began to understand how the controller works, it became clear that the relays are vital.



Next is an image that shows the controller buttoned back up with electrical tape and the three new leads extending out from it. (You can also see a plug that I was working on but later abandoned due to space constraints under the center console.) I added some velcro to the back of the controller and used it to attach it in a sneaky spot under the center console as shown in a later image. Note that the switch on the front of the controller needs to be locked in the Off position when hidden in the console for this circuit plan to work properly.



Next is one of the two three-position rocker switches I bought from Amazon. It is lighted, with a green LED that turns on in the low setting, and a red LED that turns on in the high setting. The black ground wire came attached to the switch and needs to be attached to the chassis for the LEDs to work. The three pins on the back are explained on the wiring diagram in a previous post.

 

Here I show the hiding spots for the ugly WO controllers.
Here is the center console removed. Note the wire hanging out the back. These are the wires that plug into and energize the seat heaters.



Here is a close up looking down on the back of the console. The controllers are attached to outside of the inner storage container with velcro. It's a perfect fit and therefore perfect hiding place in otherwise wasted space!

 

Another post. Here is how it all fits in the cab.

First, the chaos of clipping and stripping lots of wires. Note that I removed my driver seat to make room for this madness. I recommend you do the same. It's just 4 14 mm bolts and a wiring harness to disconnect. Very easy.



Next, you can see a couple of completed relays.



Next we see the fuse box and one of the fuse taps installed. It turned out, to my chagrin, that only one of the empty sockets was hot in ACC position. I must have screwed up when testing the empty sockets a couple weeks ago. So I had line both the switches and the main power for the heaters into just one fuse tap instead of two separate taps.



Here you can see the position of the newly installed switches and the guts behind them.



Next you can see a close up on one of the relays. The jumpers between prongs that need to be connected to a common ground are easy to see here.



Here you can see all the relays wired up and ready to roll. I added heat shrink to each of the wire connectors to minimize the chance of shorting out the circuit.



Next, finally, you can see all of the relays wired up an tucked into place alongside the cupholders under the center console. The relays are anchored in place by velcro.



Here you can see the trailer harnesses I spliced in to make it easy to quickly disconnect the center console.



Things are starting to look peachy keen now. All the wires fit really nicely under the center console when it is reinstalled in its proper place.



Here is a look at the newly installed switches. As you can see, it turns out I am a bit of a hack with the dremel I used to cut out the holes for the switches. Scratched the panel up more than I would have liked.

 

Thank you for the write up! The switch you tried originally (and I guess the one you went with also) how did you figure out which pin was high and low?

Thanks!

 

Good question. Here is the switch I used:

$9 1 Pair Heated Seat Switch, Universal 12V 3 Pins Car Seat Heater Switch Hi/Low/Off Round Rocker Control

https://www.amazon.com/gp/product/B073CKHWSP/

It did not come with any info on which pin was high or low, which was frustrating. So I tested it with a 12 V hobby battery (the kind people use on train sets). Just hook the middle pin to the (+) terminal and connect either the top or bottom bin to the (-) terminal and use a voltage tester to see if the switch is passing 12 V when rocker position is up or down.

You could also use your car battery, but that would not have been very convenient in my case. I also used the 12 V battery to figure out how the WO switch worked and to map out which pins were energized in different switch positions.

I now think it is generally true on switches like this that the pins on the back are opposite to what you might expect based on the front of the switch -- i.e., top pin is low position and bottom pin is high position. But you shouldn't bank on that. With a battery or really any DC source, it is easy to check.

 

Excellent work, I am planning on doing exactly the same thing! Do you remember what relays you used?

 

Sorry to revive this old thread, but I am wondering what you think would happen if you just bypassed the two-position Wet Okale switch and just wired this directly to a relay and simple on-off switch? Would it only be the "high" setting, would it not work at all, or would it explode?

 

Definitely Explode.