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HPA's FD Rx7 Cooling Fan Harness Integration

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hey HPA team, wondering if you mind sharing details on the HPA FD project car wiring. There is some good details on the club level course however I am still a little bit unclear on how to exactly interact with the stock cooling fan setup. I am particularly interested in how you handled the cooling fan relay setup. Stock FD's use 4 relays to trigger up too three different fan speeds based on coolant temp sensor, a thermoswitch and air conditioning button.

I am in the power supply design stages of my harness and am having difficulties trying to come up with a good way of interfacing with the stock setup, I would like to keep the 3 fan speed if possible.

So far I am thinking of using two triggers from the ECU (Haltech Elite 2000) and keeping the AC button as the third trigger, this way I can control low and medium speed based off coolant temp with the Elite and if max fan speed is needed I can still trigger with the AC button.

Would appreciate any feedback from the HPA team or anyone who has integrated a standalone wiring harness with the stock FD cooling fan relay setup. Thanks

How about changing up the setup very slightly and introducing a pulse width modulated control that would see your fan run at the correct speed all the time without the driver input?.

Many options on the market. Some do it with the use of a PDM, alternatively you can get a controller just for the fan like this one.


Sorry as far as using the factory 3 relay system I can't help. Gooduck.

Hey Brian, thanks. Definitely had thought about running a SSR and controlling it with one of the DPO outputs of the Elite. However I am concern about the fan motors reliability with being PWM'd as they where not design to be controlled that way, am I overthinking this? Stock FD fans are very good and move a lot of air so I will like to keep the stock fans.

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