Relay to cut power to ElmScan?

**ecrase2500** · 09-25-2005, 09:07 PM

Hi folks,

I searched. Concerns over the 'always-on' LED on the ElmScan interface tend to draw responses that go a little something like this:

This little light of mine,
I'm going to let it shine!

I guess that's fine for some folks, but I'm not really keen on knowingly introducing a constant power drain into my system, no matter how small. Has anyone ever tried to use a relay to cut power to the ElmScan when the car PC is off? I imagine this would involve intercepting the appropriate lead in the supplied cable, but I don't know enough about cable shielding and such to know if this would have any unintended consequences.

Any insight would be appreciated.

**evandude** · 09-25-2005, 09:18 PM

OBDII communication is done at a ridiculously slow data rate and does not involve any large power signals or anything like that, therefore wire shielding is not very important for it. however, it would probably be easiest to simply modify the board itself, by finding the power trace and cutting it, and soldering wires to each piece and then to the relay.

or if you really want to be non-invasive, get a male and a female DB-9 connector from radio shack or somewhere, and build yourself a little short pass-through cable that can be plugged in between the elmscan board and the OBD cable, that passes all the wires straight through pin-for-pin except intercepts the power wire.