Electrical
Wiring harnesses are very important to the modern automotive engine. Most modern engines have a computer controlling every aspect of the engine, ranging from air intake, engine temperature, to the back pressure produced in the exhaust system. The computer mounted on an engine is able to control it with the help of a wiring harness, which allows sensors to communicate its readings back to the computer. Wiring harnesses are responsible for assisting powerful responsive engines by quickly relaying information from sensors to the computer of an engine, so proper changes to the engine conditions can be made. My personal experience with engine wiring harnesses came this spring. It began when our team acquired an engine from a wrecked 2005 Yamaha R1 motorcycle for our senior project of building a belly tank lakester. The engine came without a wiring harness, so our team acquired a used wiring harness for the engine at a later date. I was given the task to make sure the wiring harness was “good”, meaning all the fuses and relays were working properly and there was continuity between all of the connections. I quickly learned that having a colored diagram of the wiring for the exact year, make, and model was a must.
It is very over whelming when you get a wiring harness in front of you and you have to check it. It looks like a pile of wires with fuses and relays. Also not being the one to take the wiring harness off the engine did not help, because you do not know what fuse came from where and which relay is responsible for which instrument. This is where having a colored diagram of the wiring harness you’re working with comes in handy.
I have a few suggestions that will help when working with engine wiring harnesses. The first thing would be to follow the wiring diagram and label each fuse and relay. After establishing each component on the wiring harness, use a service manual to properly diagnose the component to make sure it is working. A service manual is great because it will indicate what proper ohm reading a relay should have and which connecting pin to test for. This was a big obstacle for me because I initially assumed all relays were working properly – never assume anything in working, check everything. Also, always double check the color of connecting pins, a wire can be green going into a harness and come out brown through the sub-harness. The color wiring harness diagram will indicate all of this. Another tip is to double check all the pins in every harness connection. Yes, they can all be there, but check continuity through the fuse and relay connections. Sometimes the pins in these connections do not fully reach the fuse or relay. This is another problem I learned with the help of Kayvon, my team mate.
An engine wiring harness will keep track of air flow, engine temperature, engine speed, engine rpm, oil level, oil pressure, alternator, and the fuel injection system. There are a few added components on a motorcycle engine wiring harness which increases its complexity, such as the kick stand check, tilt sensor, engine on/off, and engine start. Most of these are safety checks and decrease the danger in operating a motorcycle.
If you follow these few tips and have lots of patience, you’ll be able to properly attach a wiring harness to an engine or at least find out you need another one.
2005 Yamaha R1 Wiring Diagram
2005 Yamaha R1 Headlight Harness