I’ve rigged up a remote car starter that integrates with HA. It’s pretty crude, but it works really well. I started with a Sonoff and a spare remote for my aftermarket remote starter. I started by cutting the trace that runs from the Mains terminal to the relay just before the relay and carved out a spark gap. This allows the Sonoff to still be powered from wall power and keeps the relay isolated. Then did the same thing for the neutral trace. I soldered a jumper from the neutral trace to the old mains leg of the relay to create a switch at the output terminal of the Sonoff. The remote only requres that you hold the button for 3 seconds to trigger the starter. That makes it really easy to rig up the switch. I cracked open the remote and soldered a couple of leads to the button and landed them in the output terminal of the Sonoff. I have Tasmota installed on the Sonoff and have it set up as an MQTT switch in HA. I setup an automation that triggers 15 minutes before I normally leave for work conditioned with the workday sensor, temperature <40 degrees and my day off calendar state = off when it fires it turns on the relay, delays for 4 seconds and turns off it also sends a TTS message to a chromecast speaker that annouces that the car is being warmed up. Like I said it’s crude, but it totally works. Now I’m excited for some cold days to see the magic unfold.
So just out of curiosity if something were to happen during your automation where the starter pretty much keeps cranking what would happen?
The remote shuts off after it sends the start signal and doesn’t reset until you let go of the button.
Most recent cars have controls built into the starting circuit. Even when you turn the key, it’s just like pressing a start button. It will continue to crank for a period of time until the engine actually starts or the time runs out. This keeps the starter from continuing to crank if there is an engine problem.
In my 2006 truck I just turn the key all the way to Start, release it to On, and it cranks until it fires. Most modern cars fire so quick that you don’t even notice that you can let the key turn back.