Anyone with a wiring diagram for a 2008 touring and up could help me out.. I'm installing a 2008 fuel tank (street glide) on a 2004 road king. The road king has three wires going to the tank while the 2008 has four wires.. I want to know where the black wire with the green strip goes.. I appreciate the help. Thanks

 

Sounds like an interesting project...unfortunately my 09 manual isn't what you need. Where are you planning on mounting the speedo being that you will be filling the tank at the top of the tank console? Reason I ask is that I have a speedo movement project going here.

 

Blk/grn is "clean" ground

Blk is "dirty" ground

orange / gry is power to fuel pump

yel/wht is fuel gauge



mike

 

Dirty ground. I have never heard of that. What is a dirty ground?

 

a dirty ground will have heavier loads on it.

the clean ground has computery type stuff on it...the 2 grounds are tied together on a Harley anyway- at the battery -

and usually to a cylinder head stud and/or chassis ( this last part may be incorrect depending on year/model)

if a dirty load has a poor connection to chassis/battery, the load or "noise" can "back up" through devices and cause screwy things.

so a "dirty grounding scheme" is used along with a parallel " clean grounding" scheme to reduce this happening.

mike

 

Dirty ground comes from battery. Clean ground comes from ECM. They connect at ONE point to establish the shared 'ground plane", so that there will NOT be a potential between the two 'grounds'. Dirty ground is what most think of as a ground. Clean comes from the ECM to control the O2 sensors, etc. Guitar is relatively close. But it is more involved that he makes it seem. He IS correct that they connect the two using two different sets of studs.

On a 2004, twist those two wires together and attach to the ground wire running to the tank right now.

Clean and dirty didn't become an issue until 2005 with that years (and newer) ECM. IIRC, the Voodoo ECM is when it came into play. 2004 bikes still had the EFI-2. 2005 is when Vodoo hit the streets, and 06 came with closed loop on the dynas. Freebird came on 2008 touring for DBW.

For folks with 2005 and newer bikes it really is important to keep these grounds separated correctly. As opposed to how one normally thinks... our ECMs use a ground potential to determine what the various sensors are saying, like the MAP sensor, the O2s, the DBW, etc. There is NOT a hot wire coming from these senors like a light switch would be, instead there is an analog signal that changes the amount of grounding these sensors allow. Clean does not directly hook to battery, because its whole purpose in being is to have a ground that is free and clear of the 'hum' from the AC three phase alternator.

When installing newer onto older... it's best to use the older way of doing things.... so, with the EFI-2? Twist them together. The clean ground in the 2008 tank, IIRC, is for the fuel sensor. Clean ground is sent to the sendor and the return would be the yellow/white.

One BIG question, tho... is the older bike EFI? If so, you should be good. Pull the pump from the tank and replace the inner hoses and install a new fuel filter. The whole mechanism pulls from the top hole where the fuel in pumped into the tank. Snap-On sells a $25 tool to remove the ring, BTW.

If it is a carb bike? Then all the guts have to come out of the 08 tank and replace with a petcock is in order, too. Not a big deal, they sell kits for this swap. It is a LOT harder to convert a tank TO EFI than to convert to a petcock.

How do you plan on running the fuel gauge? On a King... where will you put it? Or... will you simply forget that part all together?

 

Thanks- my 09 manual ( figure B-25) shows the "clean ground" bonded to the battery - , through the right ground 2 stud

I was incorrect in thinking that the clean ground is attached at the cylinder head though.

nice description


mike