Amazon: 40 amp wiring harness: Automotive XtremeVision Universal HID Battery Wiring Relay Harness 12V 40 AMP 35W/55W - H1 H3 H7 H8 H9 H10 H11 9005 9006 5202 880 881 9140 9145. 3.5 out of 5 stars 96. $9 $ 9. 99. 5% coupon applied. Save 5% with coupon. Get it as soon as Tue, Jul 9. FREE Shipping on 40 Amp Relay with Harness and Circuit Breaker This single or dual fan wiring kit includes the harness, relay and circuit breaker to wire up one or two fans quickly and reliably. This can easily be installed onto your vehicle over the weekend! Our heavy duty 40-amp relays are the best choice for any type of 12-volt wiring project.