Last update: May 30 2015

Motor Controller

The motor controller is an Evnetics Soliton1.



The controller is mounted on a bridge over the motor that is attached to the frame rails. The top of the structure is 3/16in aluminum angle, with 1/8in aluminum angle legs. The bottom of the bridge is bolted to M8 rivet nuts installed in the frame rails. The top is connected to some existing M6 threaded holes on the shock towers.

Mount Mount Mount Mount Rivet nut Rivet nut Rivet nut Mount Mount

Liquid Cooling

A Flex-a-lite 4110 TransLife Transmission Oil Cooler is mounted under the front bumper. Just above it is a Laing Thermotech DD12V-D5 Pump.

Radiator Pump Radiator Radiator

The reservoir bottle is a Vestil BTL-SW-8 with 3/8 hose fittings added. Each fitting is composed of a Summit Racing AN to Nipple Twist-Tite Fitting SUM-220756B, a Fragola Performance Systems Bulkhead Nut 492406-BL and a neoprene washer with 7/16in hole from the hardware store.

Bottle Bottle Bottle

The 3/8in hose connects to the controller with two Gardner-Westcott Hose Barb to Pipe Fittings J9032.

Controller Fitting Controller Fitting


The existing OEM throttle pedal is connected to the controller throttle input. The throttle has two sensors but the controller has just one throttle input, so the one sensor is unused. The original wiring between the pedal and the ECU has shielding on the main sensor wire alone. No other wires are shielded. The shield is grounded but not used as a ground conductor. Each sensor has its own dedicated ground wire. The OEM wire size is approximately 20 AWG.

Throttle Cable Shielding

I copied the OEM design as reasonably as I could. The best source for shielded multi-conductor cable I could find is the local hardware store, where such cable is sold as "security wire." I used 22 AWG 4 conductor cable which has the shield around all four wires. Since I only need three conductors, I joined two of the wires together at both ends so that no unconnected wires exist to act as an antenna for noise.

Throttle Plug

The Subaru accelerator pedal position sensor connector wires are identified below.

TerminalWire ColorDescription
B315-1red blueSub sensor power supply 5V
B315-2reg greenSub sensor ground
B315-3blueSub sensor signal 1-3.5V
B315-4light greenMain sensor power supply 5V
B315-5yellowMain sensor ground
B315-6redMain sensor signal 1-3.5V

Power Connections

The input power terminals of the controller are always energized, so it is important to cover them. The power terminals on the Soliton1 are very tall. To cover them completely I used the VTE 415 series battery terminal insulators - 415N0V02 (red) and 415N0V14 (black) from VTE Warehouse. I also covered the output terminals even though they are only energized when the motor is turning. The cable lugs are Genuinedealz Heavy Duty Cable Lug 4/0 AWG 1/2 in Stud.




Wireless Access

Controller settings and error messages are accessible to a Wi-Fi capable device such as a smartphone with the help of a small wireless access point. The access point can be connected under the hood temporarily. It is not connected when the car is moving; I keep it in the trunk.

Mobile Phone Access

The access point connects to the controller via an ethernet cable and is powered by a USB adapter clipped to the 12V battery. The access point is the TP-LINK TL-WR702N.

Wireless Access Point USB Adapter Power Socket

Ready Light

The controller requires a few seconds to become ready. The controller's ready status output is connected to the check engine light so that the light goes out when the controller is ready.

Check Engine Light Check Engine Light

The driver needs this information because if the throttle is pressed before the controller is ready, it interprets that condition as a faulty throttle input and refuses to operate, requiring a power cycle. A relay is used to invert the signal. The relay coil is connected to the Soliton1 programmable output named "Run indicator."