One of the key pieces in the Unleash system is the throttle interceptor. This device intercepts the connection from the onboard vehicle computer (powertrain control module or PCM) and the throttle pedal. It needs to intercept this so that the electric assist can be given priority over gas operation. There are several ways the electric assist can be proportioned, but the way our system is usually set up to operation is to have the first 0-10% of the throttle movement command 0-100% of the electric system and the remaining 11-100% of pedal travel to command 0-100% of the gas system. This way, when you’re cruising down the road at 50 mph and the pedal might be at 8% (for example), the electric motor is doing all the work moving the vehicle down the road and the gas engine is simply idling.

There is a cable that connects to the vehicle high speed CAN bus to get several important pieces of information such as shift selector position, rpm, and vehicle speed. It also is able to relay to the throttle interceptor information about button presses in the vehicle which allows us to use the volume control buttons on the steering wheel to adjust the electric assist level (when the radio is off). Feedback can be provided by a speaker on the throttle interceptor that can make various sounds/pitches.

Here’s a view of the latest revision of throttle interceptor. Normally, the unit would have epoxy potting compound covering the circuitry. But this view shows the various components. This device mounts under the dash just above the throttle pedal. It uses cable assemblies that use stock vehicle connectors so no modification is required to the vehicle wiring making it easy to both install and remove and eliminating the chance for installer error.

Another important piece of the system is what we call the alternator interceptor. This device intercepts the connection going from the PCM to the alternator. It has another CAN bus connector that ties into the Unleash system. The alternator interceptor’s job is to trick the onboard computer into thinking that the alternator is functioning correctly when the Unleash system takes over powering of the 12 volt system. The alternator interceptor sends the correct signals to the alternator to shut if off when this is taking place. This is one of the nifty ways that the Unleash system is able to maximize fuel efficiency by removing every possible load from the internal combustion engine (ICE).