LSX Fan Control

LSX Engine Swap Fan Control

When swapping your LSX engine into your vintage hot rod, there is often confusion about making the electric fans on our radiators work with the PCM. The PCM is the computer that controls the LSX engine. To make matters more confusing, if you order a custom wiring harness made for your ride along with a custom PCM program, it may be advertised to include fan control which can mean several different things. Regardless of which setup you have, all LSX fan control can be broken down into one of the following:

1) No fan control in the harness at all

In this scenario, the PCM engine harness has no provision of any kind for controlling the fans. For this setup, our standard wiring harness available here is what you need. Since the temperature switch in our harness is 3/8" NPT and the LSX motors have no provisions for accomodating this, we install the temp switch in the radiator for you.

2) The PCM is programmed for fan control and the harness has trigger wires for it, but has no relays, fuses or wiring for deliverying power to the fans.

In this scneario, you need this harness. No temperature switch is required since the PCM is programmed to turn the fans ON/OFF at a preset temperature. This will also force the fans to run if your harness has an A/C request line integrated into it.

3) The PCM has dual speed fan control and has trigger wires integrated into, but no relays, fuses or wiring harness for deliverying power to the fans. 

This is the ideal setup and how the factory fourth generation f-body and C5 Corvette control the fans in the OEM configuration. There are two trigger wires in the PCM harness in this setup that will interface with our harness - a low speed and a high speed trigger. This is a series/parallel setup which allows you to run the fans at a low and high speed . This will also force the fans to run at high speed when the A/C request is made to the PCM. For a detailed explanation of how this harness works, click here. 

4) The wiring harness and PCM has everything need to make the fans work including the fuses, relays and power wires to the fans. 

In this case, you just need the mating connectors for our fans to crimp onto your harness. Just let us know when purchasing your radiator and we will include them for you.

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