I’m revisiting an old project and need some advice. I’ve acquired a new LC-2 wideband to use as a portable tuning tool for various vehicles. My goal is to power this wideband controller using the OBDII port for convenience when tuning with my HPTuners MPVI interface. I want to avoid running separate power wires if possible and keep everything neat and portable.
The challenge I’m facing is finding a switched 12V ignition source at the OBDII port to power the wideband controller and its O2 sensor. Is it feasible to tap into the HPTuners OBDII/interface cable and utilize the 12V B+ pin on the OBDII connector? My idea is to run this 12V source to a small relay, and then trigger the relay to switch on with the ignition.
My main question is: which wire on the OBDII port can I use as a reliable ignition-switched trigger for this relay? Ideally, I’d like to find a trigger source directly at the OBDII connector itself. Alternatively, is there a suitable trigger wire on the HPTuners MPVI interface connector that could be used? (Using the MPVI connector would be a last resort due to potential software configuration). While a 12V trigger is preferred, would a 5V trigger signal from the OBDII port also work reliably for a standard automotive relay?
As a less desirable option, I could wire a manual switch into the 12V B+ wire to manually turn the wideband on and off with the ignition, but this seems less elegant. Any advice on the best approach to wiring my wideband to the OBDII port for power and ignition trigger would be greatly appreciated.
