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ECU Grounding at battery or cylinder head?

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Having read and watched dozens of webinars, your course, and installation guides, I'm a bit confused by the advice Shannon Davis (Davis Technologies) gives here - He recommends separating power and ground to clean and dirty busses, connected directly to the battery (to minimize voltage drops from high current devices - ohms law), rather than a star earth at the cylinder head.

Dedicated Power and Ground Clean and Dirty Busses: Make a clean and dirty bus for both power and ground, run directly to the battery (so it can sink any surges and not have high current devices change apparent voltage due to ohms law).

Star: High Performance Academy, other ECU manufacturers: Choose one ground spot for everything, usually a cylinder head. Prevents ground loops. Choose a 12V source (starter solenoid) and power everything from there.

Hybrid: I was thinking of wiring the ECU power and ground directly back to the battery, to keep it clean (using the EFI relay to power D1 & enable the other relays, powered from the dirty bus on the starter solenoid) . High current devices would be grounded to the chassis nearby (dual fans, fuel pumps). Ignition coils would be grounded to the heads, which get grounded to the chassis. Battery is relocated in the rear, grounded to the chassis with a 1' long ground strap.

Any worry about ground loops? My GM coolant and intake temp sensors don't seem to be grounded through the body.

I was planning on connecting the ECU's 4 ground terminals to an 8ga wire, directly to the battery (B9 B34 C1 C26)? (4x15A = 60A max current sink x 10' = .38 volts drop). The ECU supplies it's own clean 0V reference for analog sensors.


i would be happy to see the ecu grounds on the cylinder head fan and fuel pumps to the chassis, in my experience this works perfectly,

all sensors run back to the ecu so no need to worry about them.

Regards Ross


Thanks. That will be my plan!


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