This pass-through harness is for use with our E41 ECM Harness (BF01051) and E98 ECM Harness (BF01012) ONLY when using HP Tuners GM E41 ECM Upgrade Kit (ECM-00-L5P-K) to unlock the ECM on the bench. Simply remove the included fuse from the fuse holder and install the HP Tuners cable being careful to match the red wires and white wires during installation.