I've really enjoyed the last year of programming arduino and completed a few nice projects. Programming skills are improving however my electronic circuit skills are lacking. On this project I have an existing OEM circuit with two push button switches that I would like to tap into and control from an arduino. Programming side is easy. I've made a transistor switch in the past for an LED but where I'm a little stumped on this one is the conditions. I've measured the voltage across the botton and it's 3v, when I try measure the current when the button is closed it does not measure anything and the electronic circuit does not register a button push at all due to my tester. I left this till the last part of the project and up until now I've just controlled them with a relay module. Understanding this is an overkill and not wanting to avoid my electronic skills shortfall could someone assist me in the correct transistor circuit and the calcs to correctly size the transistor and resistors. I assume this has almost no current one the button is pushed so how does this affect the calculations. I understand that there will be a certain current flow from the arduino to the circuit with a transistor, can I minimize this or avoid it with low side transistor switch?