2ZR Turbo Yaris

[CrankyOldMan]

Originally Posted by 06YarisRS

Wow! Thanks Sam! If I'm understanding correctly, then grounding the "signal ground" from the F/IC at the battery would be ideal. However, would that long a run (probably about 3.5') pick up interference and cause faulty voltage readings? I could run the "signal ground" to the battery. I have tons of wire and conduit. Thoughts?

I have the Scion xD engine control diagrams if you don't. I'd be happy to send that to you if you wanted to let me know if my switched power is actually switched.

Thanks again!

In a perfect world, yes, but only if everything else in the vehicle was able to do that. There's probably a closer ground that's used by the ECU. You'd want to try and use that instead since you're connecting to that part of the electrical system. The other thing you risk doing by running a separate conductor back to the battery is called a ground loop. Basically you're making a new path for electrons to flow between the two ground reference points and causing one of them to be above zero. Here's an article with some examples of automotive grounds.

I should have a copy at home but might not have time to review it tonight.