How To: Fix CRF450X / CRF250X Tail Light
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    jpbussen
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    Joined: Sun Apr 17, 2011 2:25 pm

    How To: Fix CRF450X / CRF250X Tail Light

    by jpbussen » Mon Apr 18, 2011 12:37 am

    For Many of the CRF electric owners or anyone who has used the X model taillight, it has probably gone out on you. Well I have an easy fix to save the cost of a new one just by replacing the resistor's in the lights.

    By my judgement, Honda used two 100 ohm resistors to create the necessary resistance which is about 20 ohms too little by calculations. They would burn out and make the light useless. I have an easy, inexpensive fix for about 5 dollars, and if your LED's are still good it's only about 1 dollar. There are two ways to do this, one is two go with the stock system with 2 100ohm resistors, or you can just use 1 220ohm resistor. If you do the stock system you will need four 100 ohm 1/8 watt resistors. If you do the other choice you need two 220 ohm resistors.

    What You Will Need:

    All of these parts you can get at RadioShack which is the only place I know of to get stuff like this

    1) 4 White LED's 3.3V 25mA (If LED's still work you won't need them
    2) (Option A) 4 100ohm 1/8watt resistors
    (Option B) 2 220ohm 1/4watt resistors
    3)Utility Knife
    4)Soldering Iron
    5)Rosin Core Solder
    6)Philips Screw Driver

    1) Here are the resistors and LED's you can buy from radioshack. Choose which way you want to go with on the resistor's and you'll buy just those. Each pack of resistor's is only 99 cents and the LED's are 2 dollars for a pack of 2.
    Image
    2) Set your Light out on your work area. You will want to remove the terminals from the clip and slide the protective tubing down or completely off of the wires. Take a utility knife and not going anymore than about 1/8" down seperate the black pastic from the clear red lens. It's not going to pop off just by cutting it because there is a lip that goes into the housing.
    Image

    3) Hopefully you can do this step without breaking the plastic. I had no problems and hopefully you won't either. Take a couple pair of pliers (preferibly crescent wrenches) and poistion them about how I have them. Pry one pair of pliers in a scissors action and hopefully you can seperate the two pieces.
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    4) Now the pieces are seperated. You can see the lip I was talking about. Hopefully you were able to make it to this step with no breaking.
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    5) Now remove the two screws that hold the board onto the housing.
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    6) As You can see the two resistor's are burnt to a crisp. There's also melted plastic pegs that they use to help hold the board down even more. You will need to break the board away from the housing.
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    7) Take a screwdriver and pry the board up to break the board away from the housing but don't break anything. Using your soldering iron to melt the plastic and then pry it off might be a safer way.
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    8) Now pull the board away and pull the wires thru the grommet to get yourself some more room to work with.
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    9) Here's the back of the board. If you look closely you can see how the routing goes. It uses two series, using two LED's in a series. The positive volts goes in thru the diode (the black device in the very middle of the board) thru one LED to the next LED than thru the resistor's and to the ground. If anyone want's a good drawing of the routing just ask and I'll get one.
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    10) Now take your soldering iron and start removing the resistor's. Heat up the solder on one side and use needle nose pliers to work it free.
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    11) Make sure you pay attention to how the LED's are sitting in the board. You want to install the new one's in the same direction.
    Image

    12) Here's everything out on one side. I recommend doing one side so you don't mess up how the LED's are sitting in the board.
    Image

    13) I'm using the single 220 ohm resistor so my replacement will be different. If you do the double 100 ohm resistor's just install them just how they were originally

    14) Get the solder hot enough and mess with a bit to get the holes to open back up. This will be much easier than trying to heat up the solder and push the resistor and LED thru while keeping the solder warm.
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    15) Here's the one new LED and the 220ohm resistor installed. Since I'm using the larger resitor you will need to leave enough wire so you can twist it enought to be just as wide as the board. If it sticks out further than the board then it will hit the lense when you reassemble it.
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    16) Here's two new LED's Installed on one side and the resistor.
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    17) I hooked up the wire's to a power source and TADA!!!! It has lights!!!
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    18) Finish up the other side and now you should have all four lights working
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    19) Pull the wire's back through the grommet and screw the board back into the housing. You can try to melt the plastic pins back to the board if possible but probably not necessary. If you did a nice clean job it should look just like it's factory.
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    20) Like I said make sure if the resistor isn't wider than the board so it will clear the lens.
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    21) Super glue the lens back on. The lens has a slight curve to it so it has only one way to go back on so it's hard to get it back together wrong. Use rubberbands to hold it together or some sort of clamps that won't break it. Once your done it should look good as new.
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    Last edited by jpbussen on Fri Sep 14, 2012 3:04 pm, edited 1 time in total.
  • Back2-2
    Posts: 1148
    Joined: Tue Jan 04, 2011 3:31 pm

    by Back2-2 » Mon Apr 18, 2011 6:31 am

    Wow ! Excellent write-up and top knotch fix it job !

    Thank you. This is a print & save for me.
  • scotsy
    Posts: 119
    Joined: Thu Sep 17, 2009 11:19 am

    by scotsy » Mon Apr 18, 2011 6:32 am

    Your 1 and only post and its a gem for X owners :D

    Should be easy to follow seeing as i understand it and i struggle with a household plug :oops:

    Well done JP :P
  • User avatar
    124
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    by 124 » Mon Apr 18, 2011 9:35 am

    Is this your personal writeup or copy/pasted from another source?
    If copied, please state your source.
    Either way, thank you for the good information.

    One minor comment from an EE, my two pennies if you will. I would recommend using solder removal wick to clear the PCB holes before reinstalling the new PCB devices. It will make assembly much cleaner.
    70' Honda CT70 (Trail 70; Gold)
    16' KX450
    16' KX85
    12' YZ125
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    crfsonly
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    by crfsonly » Mon Apr 18, 2011 9:40 am

    first, welcome to the site! excellent how-to! i'll make that an official how-to article.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
    _________________
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  • 357Warrior
    Posts: 153
    Joined: Wed Oct 27, 2010 7:53 pm

    by 357Warrior » Tue Apr 19, 2011 8:10 pm

    awesome write up- just in time! Mine just went poof.. :roll:


    Thanks
  • scotchss
    Posts: 1
    Joined: Tue Sep 20, 2011 1:53 pm

    by scotchss » Thu Oct 13, 2011 8:38 pm

    Mate, this is a great fix
    Thanks heeps, better than standard for sure!!
  • mxcross362
    Posts: 3
    Joined: Thu Sep 13, 2012 10:17 am

    Tail light repair

    by mxcross362 » Thu Sep 13, 2012 10:32 am

    I put the resistors in and new leds but only 2 on one side light up. I know the other 2 Leds are good they light up with 3 volts applied to each bulb. Could you please send me a diagram. I might have to jump some bad traces.
  • User avatar
    jpbussen
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    Joined: Sun Apr 17, 2011 2:25 pm

    by jpbussen » Fri Sep 14, 2012 3:03 pm

    Well it's been over a year since I've been on here, and I just want to thank you all for the great comments. I'm glad I could help you guys fix an annoying problem, and I enjoy doing my own work so I thought I'd also share it with you guys.

    To 124, yes this is my own personal write up, done with my own two hands. Please credit me though if someone else wants to repost this. Yes I use it the removal wick quite often and it's very helpful, but I didn't want everyone to think they had to have it to do this repair.

    To mxcross362, Each side is seperated to it's own circuit, so if you only have one side not working then that's good in a way. Check to make sure you don't have a broken board wire, resistor or a bad solder first. But to be honest I did this over a year ago and I forgot to make the diagram before it has vanished from my memory. If you could take a picture of the back of the board I could help you out. Let me know because I'm glad to help.

    Thanks everyone and have a great day.
  • mxcross362
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    Joined: Thu Sep 13, 2012 10:17 am

    by mxcross362 » Wed Sep 19, 2012 8:40 pm

    Got it fixed, had to make a trace bypass. That 2 year electronics degree finally paid off.
  • mossman77
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    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Tue Jan 13, 2015 1:07 pm

    The standard resistors on the tail light PCB are not 100 ohm. If that were the case, there would be more than 150 mA flowing through the LEDs and they wouldn't last long at all at that current. The engineers at Honda certainly wouldn't have selected this resistance value. I tail light PCB on my '07 uses four 560 ohm resistors. There are two circuit branches with two LEDs and two resistors in each branch. Two 560 ohm resistors in parallel yields 280 ohms and a current of about 28 mA per branch (assumes 12V supply and 1.8V voltage drop across each LED), which is just right. The reason these circuits are failing is likely due to moisture causing corrosion and short circuits or the LEDs burning out, not a design flaw. BTW, I just repaired my tail light (only one branch was working) and the reason the branch failed was because one of the LEDs failed. And FYI, you don't need to use clear LEDs, you can use red, which is actually what came stock. I used high-intensity LEDs, which in hindsight may have been a mistake. They are blinding! Oh, and you can remove the tail light lens using a heat gun and gentle prying motion with a thin flat bladed object, such as a razor knife or miniature screw driver. Here is the schematic:

    Image
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    crfsonly
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    by crfsonly » Tue Jan 13, 2015 5:55 pm

    mossman77...welcome to CRF's Only! Excellent addition to this How-To.

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
    _________________
    CRF Parts and Accessories: http://crfsonly.com
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Wed Jan 14, 2015 8:44 am

    Let me be clear that the procedure described by the OP will in fact work, as long as you use a single 220 ohm resistor per branch. Do not use 100 ohm resistors! You will fry your LEDs. If you are going to use 220 ohm resistors, be sure to remove all four of the old resistors, otherwise you'll be putting a 220 ohm resistor in parallel with a 560 resistor. This yields a total resistance (per branch) of 158 ohms, which will allow too much current flow. One 220 ohm (or better yet, 270 ohm) per branch or two 560 ohm resistors per branch (as shown in the schematic above) is what you want to use.

    Image[/img]

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