OEM Neg battery cable with included pigtail.The small wire bolts to the fender apron & the black tubular plug connects to a matching plug at the end of the main engine harness.This small wire is the EEC ground & if left disconnected,youll have driveability issues or the engine will stall once the key is released to the run position.This is the 3rd most important ground in the circuit and the one that completes the ground loop,so dont forget it.