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Base Plate Wiring Harness Installation - 2010 Honda Fit

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How to Install a Base Plate Wiring Harness on a 2010 Honda Fit


Today on this 2010 Honda Fit we are going to install a diode isolating kit part number 38955. The first thing we need to do to get started is that when we take our wire harness we are going to tape up part of this and then we will do the whole length and periodically apply some tape to keep everything under control. We will let our ground loop hang out and continue on. What we are going to do is take our 4-pole first and we are going to route it down towards the grill and we are going to pull it out by our base plates. Just leave it like that for now. 00:39

Then we are going to take our ground loop and we are going to attach to this factory ground that we have right here. We will put that on the bottom. Then take the other end of the harness and wrap it around the battery underneath some other engine components here. Hopefully we can route this down far enough where you can reach at the bottom and start pulling it on through. We ran the wire through the engine compartment over the front suspension components and made sure it was not close to anything that was moving or rotating. Then we took the wires and ran it through some plastic sheeting and we ran it all the way to the back. 01:27

We are at the back of the vehicle we have got two wires. We are going to take the green and brown wire and go over to the passenger side of the vehicle. Make sure you stay away from the exhaust go up over the bumper bracket and then of course on the yellow we are going to go to the driver side. The next detail we are going to cover is the wire harness on the vehicle. This one has a three wire system which means it has a separate turn signal, running light, and brake light. On our tail light assembly we have a turn signal and in the same bulb here we have a brake signal and a running light. On our kit it has only got four diodes. What is going to happen is we are not going to use the turn signal on the vehicle as a turn signal. What we are going to do is actually use the brake light as our turn signal and brake. That way you do not have to have extra diodes for every function. Next we will take of our tail lights. We are going to get behind the access panel here. First we will start disconnecting the light with the wire harnesses here. I can not see it but on the other side there is a tab, push down on the tab and the wire harness comes apart from the tail light. Next there are three nuts that we have to remove. There is one more wire disconnection we need to disconnect that is easiest to get to when you are on the outside. Set the light to the side. 03:23

Next we are going to use a test light to figure out which wire color does what function. We are going to start off with a running light circuit so we have the running lights on and we will test the ends to see which one does what. Looking at the back of our connector it looks like it is going to be the gray wire. Peel back some of the insulation tape. Next we will show you the diode itself. It is labeled in in and the bottom is labeled out. The out always goes the bulb that you want to use to illuminate. The input is going to be two of them. One input from the car when it is not being towed and there is going to be an input for when the car is being towed. Basically what we are going to do is cut our wire in half. We are going to strip the wires back and we are going to put the supplied terminals on each end and just push it into place. Crimp it together. Install the diode. We have got the input and going out to the bulb we are going to use. That is our running light circuit done, now we will test for our brake signal. Our brake wire is going to be a teal colored wire. Install the next diode out going to the bulb and in from the car. We will double check our connections through the diodes on the other side again just like we did we tested for our signal so check the running lights first and then we will check for the brake signal. Off, on. Lets pull the wires from the bottom up. We are going to use this piece of wire just to run it down. Wrap the wire around the wire we are going to pull up then pull it up to the light. Cut off the excess which we do not need. Then we will apply more spayed terminals to these ends and plug them into their appropriate spots. 06:05

Yellow is the left turn signal so match up the diode that was left turn. The brown wire is going to our diode into the running light. It will also be a good idea once we have the tail light installed to test the functions one more time and make sure all of the connections are good. We have got our running light circuit and that is working. Then our brake signal and that is working. This side is good, we will go over to the passenger side and do it all over again. We are on the passenger side of the vehicle and we are going to test the wires again. Note they are the same colored wires so chances are that it is going to be the same pattern. We will try the running lights. Our running light circuit again is going to be this gray color. We will try the teal color wire for the brake signal. It is going to be the same thing as before. Teal is going to be the turn signal circuit and the gray is going to be the running light circuit. Add the diodes to these wires just like we did before. We have got our other two wires pulled back. The brown wire is going to go to the running light circuit and the green wire is going to be the turn signal and brake so that will go to the brake light signal and we will reattach the tail light. Lets apply power to the system. First turn on the running lights and now we will hit our brakes and then we will do our right turn signal and then we will do the left turn signal. You can see the diodes with just four of them we have got our running lights, we have got our turn signals, and our brake lights. With that, that will finish our install of part number 38955.


Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Ryan G
Test Fit:
Ryan G
Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Mike H
Video Edited:
Mike H
Employee Andrew K
Video by:
Andrew K
Employee Jeff D
Installed by:
Jeff D

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