70A Dual Fan Relay Kit – EFI Applications, Negative Trigger

(1 customer review)


This kit is for vehicles with Electronic Fuel Injection (EFI) with negative (-) fan triggering, which includes most of the aftermarket EFI offerings from all of the major manufacturers.  This completely waterproof kit installs easily and plugs directly into your electric fans via standard fan plugs – of which most of the major fan manufacturers use.  Harnesses dressed in Split Braided Tubing for that show car look!

Triggering is fully automatic (see specifications below for specifics).  Powers fans requiring up to 35A continuously with minimal voltage drop!

Includes full color step-by-step instructions and all hardware shown.

Full specifications outlined below.



Wiring to Battery: Dual 10 AWG TXL, terminated with a 5/16″ eyelet
Wiring to Fans: Dual 10 AWG TXL pairs, terminated with OEM style fan plugs
Maximum Current Capability: 35A per fan for a total of 70A
Typical Voltage Drop through wiring when driving a pair of 16″ fans requiring 25A continuous each with 13.8 VDC of input:

  • Immediately after power up: 380mV or 2.8%
  • After 30 minutes of continuous operation: 430mV or 3.1%
  • After 1 hour of continuous operation:  440mV or 3.2%

Triggering is as follows:

  • Fully automatic via low current fan outputs from EFI ECU
  • Compatible with ECUs outputting a Negative (-) trigger for the fan circuits
  • Fans can be set to come on at different temperature settings, assuming the ECU has dual fan outputs that can be programmed to activate at different temp settings

Dimensions of Relay Module with mounting bracket installed:  3″ x 3 1/8″ x 2″ (76.2mm x 79.38mm x 50.8mm)

Harness Lengths:

  • Power Harness to Battery:  3ft
  • Output Harness to Fans:  3ft
  • Trigger Inputs from ECU:  2ft
  • Switched Power Harness:  6ft

1 review for 70A Dual Fan Relay Kit – EFI Applications, Negative Trigger

  1. Les Bowles (verified owner)

    Wowzer! After I started up the 442, I swear I could have put it in neutral and the two 13″ fans would have slowly sucked it forward when they were both running. What a difference in fan speed, to say the least! Another high quality and purpose-built solution from Tony. This kit effectively and correctly replaced the two relays and a lot of unnecessary wiring for my dual 13” fans in a properly designed, durable, and quality constructed solution. I’ve used several of his products and his publications for the electrical system on my custom build in the past and I’ve never been disappointed. Thank you, Tony!

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