LS1 2 Speed Electric Dual Fan Harness Relay Retrofit Upgrade LSX Radiator Fans

Description

Pictured fans are not included. Each purchase will receive 1 harness. Look at the second picture for feedback on this item. This harness is made with thick 10 AWG wire and the heavy duty relays will run the fans in low and high speed. Detailed instructions are included. The harness comes with preinstalled connectors for fans from 85-04 Corvettes or 85-02 V8 F-Bodies. That includes fans from the LS1, LT1, 350 TPI. Look at the picture to compare to your fan connector. We also have another fan harness with no fan connectors so you can connect to Flex-a-Lite, SPAL, etc.
This harness will work if you are EFI or carb. You can use the ECU/ECM to turn the fans on or run them to a simple switch if you prefer. This harness installs easily via power and ground, and when the blue/green wires get ground via a switch or your ECM, it will turn the fans on. The red power wire runs straight to the battery (or a red plastic junction box near the alternator on some GMs). The black ground wires can go to a clean grounding point. This harness can be used via a GM ECM, an aftermarket standalone ECM, or another car manufacturer ECM. The harness just needs power and ground to run the fans, and then a ground signal for the blue/green wires (which is what most ECMs use) will set the fan speed. If using a GM ECM, the green and blue wires are precrimped for a GM ECM connector and will go to the factory spot on the ECM connector to control the fan speeds.  When the blue wire is grounded via ECM or switch, it will turn the fans on low speed and the blue/green wires grounded together will turn the fans on high speed. You can control the fans via simple switch or program the ECM to do it for you with coolant temp and AC compressor or line pressure if your vehicle is equipped with AC. Many modern factory ECMs turn on the fans under these conditions already.
The harness will ship ASAP with tracking.
**If your 99-06 GM Truck ECM does not have factory electric fan control, it will need to be turned on via a tuner shop with access to ECM controls, typically via HPTuners or EFILive. They can tell the fans to turn on with coolant temp and AC line pressure / AC Compressor.