The Baja Designs 640127 is an automotive-specific RTL wiring harness that connects a Baja Designs RTL rear light bar to a vehicle's electrical system. Despite the "turn signal" wording in the product name, the manufacturer's spec lists this harness as without turn signal function. Its built-in relay powers the running light, brake, and cargo/reverse light functions, and its lead runs far enough to reach the rear of a car or truck. The buying case is a matched, relay-based harness for those three functions, not a splice-it-yourself kit. Anyone who wants amber turn signal action from an RTL-S bar needs a separate turn signal harness, so check the part number before you order.
Fitment is listed as universal rather than model-specific, so match the harness to your light bar and your vehicle's tail-light wiring before installing. The manufacturer's install sheet calls for disconnecting the battery ground first, then routing the four-wire lead by color: black to ground, yellow to brake, blue to reverse, and red to running light. Plan to drill a 3/4-inch hole for the reverse switch in the cab and mount the relay away from heat and moving parts. Owners on user forums note that a trailer-plug tap can combine the turn and brake signals, so verify circuits with a multimeter before tapping.
No. The manufacturer lists it without turn signal function and points RTL-S buyers to a separate turn signal harness. Confirm the correct part number with the manufacturer before ordering, because its literature gives different numbers.
No. The manufacturer states the RTL bar ships without a wiring harness and that the automotive application requires part 640127.
Yes. The manufacturer's instructions call for a 3/4-inch hole to mount the reverse light switch in the cab.
This is a moderate electrical install. The manufacturer's instructions list a 10mm or 1/2-inch socket for the battery terminals and a 3/4-inch drill. Start by placing the vehicle in park, turning it off, and disconnecting the battery ground. Route the brake and running light leads to the matching trigger wires, using the included extension if needed. Mount the relay away from hot, sharp, or rotating components. Finish by attaching the positive and negative battery leads to their matching terminals and then reconnecting the battery ground cable.
