Due to several long trips planned in the Caterham this summer I decided to install an aftermarket Cruise Control. I used the Rostra 250-1223 all electronic kit as it uses a stepper motor instead of vacuum to pull the throttle open. Much more friendly to a turbo engine which tends to run out of vacuum as the boost comes on on long hills resulting in the car slowing down.
Installation was a PITA due to the lack of space to install the components and then getting my hands in there to wire them up. I've been working on this for almost a week, having to walk away from it several times due to frustration. However, it is now installed and working very well.
Originally I used the sensor on the front wheel that provides the signal to the electronic speedometer. It provides a 7 volt square wave signal just like the cruise control instruction book requires. The cruise control refused to recognize the signal even though I had measured it within their spec of 5 - 12 volts. I had to use a magnet zip tied on the driveshaft with a sensor mounted above it attached to the bracket of the hand brake. A flip of the microswitch from square wave to sine wave and all was well. I forgot to take a picture of it before I put the console cover back on.
The first picture shows the black control module tucked behind the aluminum water tank and the plastic water/methanol tank, the only place I could find under the bonnet to put it.