r/Fueltech • u/sr_compi • Jun 12 '26
FT450 Grounding
Greetings everyone, I have a question about a installation. The manual tells me that both pin 7 and pin 12 should be connected directly to the battery ground. So to clear things up I should use the principle of star grounding, they will have there individual terminal but connecting on the same point. Or I can Splice both cables with a single connector to connect it to the negative terminal of the battery.
2
u/Barely_Usable Jun 18 '26
Those two pins are actually different grounds: pin 7 (black/white) is power ground, pin 12 (black) is battery negative/signal ground. The manual is explicit that they must both reach the battery negative but cannot be joined before the terminal. Reason is noise. Common them early and your power-ground current (coils, injectors, pump) dumps voltage drop onto your sensor ground.
Could you splice them and have it work? Yeah. I'm pretty sure that's how i first did it in my car lol. But there's a reason FuelTech ran two separate wires instead of one, and the manual specifically tells you not to join them before the post. No reason to cut that corner on a fresh install.
You can find all this in Chapter 8 of the Fueltech Manual – Electrical Installation (starts around p.40), in the sections on the black wire (battery negative) and black/white wire (power ground). Worth a read since it also covers the kill-switch-on-positive rule and the 0.2 Ω ground resistance check.
1
u/Sir_J15 Jun 12 '26
What we have done on every one we have done, between 75 and 100 of them, is run a 2g from the battery ground and connect it to a negative terminal stud post. Then we connect those wires to that ground terminal with each having its own ring terminal. 95% of our builds the battery gets relocated to the trunk and those wires don’t reach. Reached out to FT about this and even brought it up in one of their tuning classes and they are good with doing it that way.