The first problem I ran into was that of controlling the 3-tier heat and ventilation functions on the new seats. On the "Exclaim" Soul in the junkyard, the seats were controlled by 2 momentary rocker switches, with 6 LEDs to indicate the level of heat/ventilation (Circled to left). My first thought was to simply take those switches and install them somewhere in my car. However, further investigation showed they are not removable switches, but rather are buttons which are integrated into the overall AC Control Module (Shown to left).

So, if the controls are integrated into the module, can I just swap the entire module? Of course not, that would be too easy! The wiring, connectors, and functionality for this module are completely different between the Base and Exclaim models, making that idea also dead-end. Not ready to throw in the towel quite yet, I bought 7 days of the online Kia wiring schematics and did some digging.

In the wiring schematics, I found some good news - it appeared the heated/ventilated seat switches were just that - analog switches. Kia had simply integrated the heated/ventilated seat switches into the AC Control Module. This meant that all I needed was a switch of the same functionality and a power source in order to control the heat and ventilation functions in the seats.

Since I purchased the online Kia wiring schematics, I searched the other Kia models to see if any others had a similar switch for their heated/ventilated seats. While most had only 2-tier seat switches, the 2014-2015 Kia Forte happened to have the switch I needed (to the left, P/N: 93340-A7100AK5). As a bonus, the Forte switch has a similar OEM appearance and fits the interior aesthetic in the 2nd Gen Soul.

The wiring diagrams proved that this Forte switch is functionally identical to the buttons in the Soul, however in the Forte it is not integrated into another module: Perfect! This independent Forte switch can transmit the required signal to the seat to activate the ventilation or heat functions.

While I could now see a viable path forward for seat control, the fun was far from over. The next step is to assess the wiring pinouts to see how a custom wiring harness needs to be made.

There are three main functions within the upgraded seats: Heat/Ventilation, Powered Adjustment, and Airbags. Airbags, fortunately, have their own small connector which does not need to be touched for this project. Both Heat/Ventilation and Powered Adjustment wiring is inside the large, main connector to which a custom harness will need to be made

Each seat has heating elements and fans which are controlled by individual control modules, 1 for each seat (P/N: 88995-B2000). These modules are integral to the seat and were attached to the bottom of my Junkyard seats. As shown in the diagram to the left, the "DRIV. SIDE HEAT/VENT CONTROL MODULE" receives signals and power through the main seat harness connector. This means, all you must do is create a wiring harness that ends at the main seat harness connector, and you don't have to do any modification to the wiring within the seat, which is a huge plus!

The general scope therefore is:

1. Run signal wires from the Forte seat control switches to the seat harness connectors

2. Run power wires from the proper power sources to the Forte seat control switches and the seat harness connectors (RED WIRES ON DIAGRAM)

The heat/ventilation control modules require 3 different types of power sources: HOT ALL TIME, HOT IN ON, and HOT IN ON AND START.

-> HOT ALL TIME provides power constantly, even when the car is off. I sourced this power directly from the battery by running a 10AWG power wire through the firewall, then adding a custom fused power distribution panel in the cabin. This allowed me to have 2, 20A-fused, 16AWG, HOT ALL TIME power wires, one for the driver seat and one for the passenger seat. These wires have substantial power requirements, providing power to the seat heating elements, seat adjustment motors, and the ventilation fans. It is because of these substantial power requirements that I ran direct power from the battery and did not use fuse taps. The creation of this custom fuse panel will be discussed in the next section.

-> HOT IN ON provides power only when the key is in the ON position. I sourced this power from the fuse box, utilizing fuse 12, "A/CON 1" which is a 7.5A-Fused HOT IN ON power source.

-> HOT IN ON AND START provides power when the key is in the ON and START positions. The difference is power is provided when the car is being started. I sourced this power from the fuse box, utilizing fuse 25, "MODULE 1" which is a 10A-Fused HOT IN ON AND START power source.

To tap into A/CON 1 and MODULE 1 fuses, I used generic fuse taps, available on Amazon (Pictured to Left). I labeled the tapped wires accordingly so I could remember where they went.

To safely distribute multiple fused power wires from one thick battery wire requires a fuse panel. I purchased this small, 6-fuse, 5" x 5" x 1.5" box on Amazon, and wired it up as shown in the pictures to the left. The thick cable coming from the left is the power from the battery through the firewall. The thick cable coming in from the right is a ground, which utilized an eyelet to be bolted on a piece of the dashboard's frame. Both thick cables are 10AWG. Then, the three smaller wires coming out the side are my 20A fused power sources (NOTE: only 2 fused wires are required for this project, the third one is for an unrelated modification to this particular car).

To mount this small fuse panel, I utilized 2 small Velcro strips placed on some foam insulation under the dashboard HVAC assembly and to the right of the gas pedal (Pictured to left with trim panel removed). With the lower trim panel in place, it is entirely invisible, and the wires just tuck in behind the trim panel and carpet.

The length of the power wires running from the fuse box to the seat control switches will depend on the locations of the switches in the cabin. There are a number of locations these switches could be mounted, but I chose the removable trim panel at the front of the center console. As pictured, I chose to place the switches to either side of the shifter. This spot was not perfect, as some people may hit the switch with their knee when driving.

I used a drill and a Dremel to carefully trim the correct-sized holes into the trim piece. I used JB-Weld to mount the switches to the trim piece, using aggressive sandpaper to scuff up the plastic prior to application. This scuffing was key to a strong bond.

A 3D-printer would greatly expand your options for switch mounting location, as it would allow custom plastic brackets to be made. Iteration 2 of this setup design will include 3D-printed mounting brackets as I now have a 3D-printer and did not during iteration 1.