2012 BMW X5 Trailer Wiring | etrailer Call 800-298-8924 to get Expert Service ordering a Trailer Wiring for your 2012 BMW X5. Complete installation instructions and lifetime technical support on all Trailer Wiring purchases. Lowest price guarantee on accessories for your BMW X5 and the fastest shipping available. BMW X5 Trailer Wiring | etrailer Trailer Wiring Harness Installation - 2012 BMW X5. Today on our 2012 BMW X5, we're going to take a look at and show you how to install the Tow Ready Upgraded Heavy-Duty Modulite Circuit-Protected Vehicle Wiring Harness with Install Kit. The part number is 119190KIT. Here's what the alternative mounting solution looks like.