Diesel Glow Plug Wiring Harness | O'Reilly Auto Parts Order Diesel Glow Plug Wiring Harness for your vehicle and pick it up in store—make your purchase, find a store near you, and get directions. Your order may be eligible for Ship to Home, and shipping is free on all online orders of $35+. Check here for special coupons and promotions.Founded Location: Springfield, MO Power wires to glow plug controller get VERY hot, new Aug 18, 2013The wiring harness I installed only replaces the wires and fuses going from the controller to the glow plugs, nothing else. So the wires getting hot were never changed. Here's some additional info. When i noticed the ground wire for the old controller wasn't hooked up, I also couldn't find where it was supposed to be hooked up.