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Thread: Output harness for dual electric fans.

  1. #1

    Default Output harness for dual electric fans.

    So I upgraded my original Terminator system to a MPFI. The 558-104 harness has a output plug (8-pin) that's completely different than the 3-pin output plug I used to run my fans with the original harness. Which output harness do I need and any advice on wiring this up correctly?

  2. #2
    Join Date
    Dec 2009


    Originally Posted by Danny Cabral
    Dominator Auxiliary Harnesses:

    To connect up to 4 Inputs & 4 Outputs to the EFI Main Harness, use I/O Auxiliary Harness 558-400.
    Eight Wire I/O Auxiliary Harness Connector Pin-Out (also in the Holley EFI Wiring Manual - LINK):
    Pin A...A12...White/Blue (Input #1) F,5,2,T,H,G
    Pin B...A3....White/Red (Input #2) F,5,2,T,H,G
    Pin C...A13...White/Black (Input #3) F,5,G
    Pin D...A4....White/Green (Input #4) F,5,G
    Pin E...B12...Gray/Yellow (Output #1) H,P+
    Pin F...B11...Gray/Red (Output #2) H,P+
    Pin G...B10...Gray/Black (Output #3) G,P−
    Pin H...B3....Gray/Green (Output #4) G,P− (Holley 558-400 I/O Auxiliary Harness Instructions)

    The 558-400 I/O Auxiliary Harness is 20 feet long.
    It's "plug & play" into the main harness, and an easy way to connect common things like an electric cooling fan (LINK).
    This I/O Auxiliary Harness isn't required for the optional oil & fuel pressure transducers, which are also "plug & play" into the main harness.
    The oil & fuel pressure transducers are used for Data Monitoring, Data Logging and setup Outputs based on oil & fuel pressure.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, 36-1 crank trigger, 1x cam sync, 200A 3G alternator, Optima Red battery, R134a A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM converter, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  3. #3


    Thanks for the quick reply Danny. I’m very close to having it up & running after almost two years!

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