PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Keeping fans on for a set time after car turned off

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Old May 30, 2026 | 07:09 PM
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Default Keeping fans on for a set time after car turned off

I am running a single turbo 5.3 with Holley Terminator X. I have 2 Chevy Volt fans controlled by the Holley with pwm. Like most turbo cars, under hood temps can get hot, especially after the car is parked and there's no air flow. I have hood vents that allow some hot air to flow but not nearly as good if the radiator fans stayed on.

I was wondering if there was any way to keep the radiator fans on for a set time after the car turns off. From what I gather, it doesn't seem like this is possible with the Terminator X. Does anyone have any suggestions on how to do this?

Ideas:
1) Run some sort of timer device that keeps power to the Holley ECU after car turned off
2) Run the same timer device spliced into the fan wiring directly? Not sure how that works with the pwm
3) other??

Let me know any ideas or thoughts

Thanks

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Old Jun 1, 2026 | 06:58 PM
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I’d be curious as well. I used that feature when I was running the stock PCM. I swapped to a dominator last year and I miss that feature!
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Old Yesterday | 10:54 AM
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Other computers like a Haltech or MoTeC have built in functions to hold power after key off, no such thing exists in the Holley. You might be able to run a timer relay to the switched power input on the Holley to simulate something similar but I really don't know how it would behave doing that.
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Old Yesterday | 12:16 PM
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Hella makes a time delay relay I used on my turbo scavenge pump but not sure it had enough amperage to cover a fan but you might have a look..
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Old Yesterday | 12:18 PM
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Originally Posted by JimTA
Hella makes a time delay relay I used on my turbo scavenge pump but not sure it had enough amperage to cover a fan but you might have a look..
Problem being it's a PWM fan and the Holley needs to remain powered on to give it the signal it needs to stay on.
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Old Yesterday | 12:20 PM
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Originally Posted by NicD
Problem being it's a PWM fan and the Holley needs to remain powered on to give it the signal it needs to stay on.
good point.. i missed that..
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Old Yesterday | 10:32 PM
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From: Mefis
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Timed relay and this setup?

https://ls1tech.com/forums/forced-in...-less-diy.html
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