Trigger wire when key is inserted into ignition

[badufay]

Hi all... trying to find a way/a wire that i can use as a trigger wire, that will power on and stay powered on when the key is inserted into the ignition regardless of key position. I know older VWs had a wire on the ignition switch that served this purpose. Car in question is a NAR 2017 VW GTI S (non Kessy).

Thanks,
Ben

[DV52]

badufay: Hi.

Hmmm......... it helps in answering your question of we understand exactly what you are trying to do

I'm not sure if you are aware that NAR model cars are built different to the mk7/mk7.5 Golfs that are sold on the rest of this fragile blue planet. This said, I'm fairly confident that the set-up for the ignition/starter switch is the same, regardless of country of sale. Below is the set-up for the switch




So, the switch is physically located at the end of the barrel lock mechanism for the ignition key. The part number for the switch is 5Q0-905-849. As is shown, the switch has a 5 x wire loom that is terminated on a 8 x pin connector that plugs into the Steering module. In my diagram, the 8 x pin connector is labelled T8af. I've also shown in the table on my diagram how the contacts in the switch make/break for the various positions of the ignition lock.

In terms of your specific question, the 'S contact" in the switch registers when the shaft of the ignition key is physically inserted in the barrel lock. The "S contact" remains closed (regardless of the ignition position) until the ignition key is physically withdrawn out of the barrel lock.

I have no idea whether the "S switch" contacts are suitable for your purpose because again, I don't know what you are attempting!!

Don

[badufay]

Thanks so much for the detailed information — that wire pinout is incredibly helpful. I noticed there are two pins triggered by the "S" terminal, which is great. I'm planning to use this as a trigger for a relay that supplies 5V power (12 volt down to 5 volt) to a wireless CarPlay adapter.

For a bit more context: due to how the car wakes up the infotainment system (e.g., when doors open or the key is inserted even after the car is turned off), I've run into an issue where the adapter connects automatically — even when I'm just opening the door — and stays connected, sometimes keeping the radio on as well. Right now, I have it triggered off a standard terminal 15 wire, but I’m looking for a solution that’s only active when the key is inserted, to avoid these unintended activations. Do you think pin 3 or 4 would be the better trigger option? Im leaning towards pin 4?

The way i have this setup is I have modified a usb extension cord that i cut the power wire that is powered from the car, and rewired it to this relay, bypassing the power on/off from the car through the USB port.


Thanks again for your help.
Ben