The weather and just being really busy with trying to move house has been taking up my time lately. I ordered a GSM switch some time ago. Today I replaced the single switch GSM switch I had already fitted with the new 4 relay one.
A GSM switch uses mobile phone technology. With a GSM switch and a SIM card, I can control 4 relays from encoded text messages. I have an app that uses simple buttons to generate the messages. The first one I fitted only had 1 relay output. I used this to switch on my ignition for the cooling / heating systems only. I had to remember to press the 'heat' button to bring on the electric heater. The plan was to have another relay to bypass the button, but this also requires that the fan is on or the heater relay won't work. It is do-able with one relay, but since I was doing this I wanted to be able to control more, so I bought another GSM switch that can control 4 relays. I made a small bracket from some L section aluminium and mounted it on the old cruise control module bracket. It was really cold today, so I just wired it the same as before, so I still have to remember to press the 'heat' button when I park so it is ready when I want to come out to a nice warm defrosted car.
I need to run wires to use another relay to bypass the heat button. I also want to bring on the heated rear screen at the same time, but this uses an electronic button so one push sets a timer, second push turns it off again. The relay outputs can be pulsed, so this will be another function. In order to do this I need to get inside the heated rear screen button as the terminal to switch states is not accessible externally, so I need to get in the switch and run a separate wire so I can mimic the button push with a pulse from the relay on the GSM switch. Then I need to run the wires from the heat button and rear screen heater to the GSM switch. Fortunately most of this can be done inside the car, so a bit warmer while I'm working I'm hoping to do this tomorrow.
