Illumination for the S2000 Switch
Okay… we had a customer ask us a very good question about wiring into the S2000 switch. We missed the switch illumination in our last app note and this raises an inportant point on how the MASTERCELL inputs work on ISIS.
Remember that all of the inputs are pulled to ground. Also, remember that we build a significant amount of circuit protection into the system. This means that we protect all of the inputs on the MASTERCELL from electrostatic discharge (ESD).
I just happen to know a thing or two about ESD. In a previous life, I managed a piece of business that made suppressors for ESD. Some of these parts were board mounted surface mount components. Other parts were inserted into connectors for high-end aerospace and military applications. I even published a few papers on really esoteric high-bandwidth testing methodologies for transmission line pulse testing.
Anyway, the diode arrays that we use to protect the inputs from ESD are sensitive to DC voltages above 9 volts. This means that you cannot apply the battery voltage to any of the MASTERCELL inputs. When you wire ISIS into your car, you have to take care to make sure that the inputs are only connected to ground.
So, to make the illumination work for the S2000 switch, you need to physically separate the power to the internal light bulb from the contacts for the switch. This is very easy to do and it should take you less than 15 minutes. We added a second S2000 switch app note to our Reference Library.