Is there a way to have the OBD connector provide power to a connected device when the engine is off?

Question

I want to connect a device to the OBD connector (it draws less than 100mA) and have that power there even when the engine is off. I have tried on one engine and found that when the engine is off, the power is not passed through. If this is typical, is there a way to enable this? I guess it might be different per vehicle then? If you could enable this, would it potentially voice engine warranties?

Answer 1

If you need to run electirc devices from your vehicle while it is not running, then look into buying a power inverter, they are designed just for this purpose. They range in ampergae capabilities and most will accomodate either a household type plug or a cigarette lighter type adapter. Your OBD port is not a power plug and should not try and be used as such, since you run the risk of damaging your vehicle's computer system, which is not a good thing.