Hooking a tach up on 06 softail its a bikers choice 3 wire red,black green

SOURCE: How to wire a tach on 05 heritage softail

Locate & route Black lead to ground / 2004-later softail: On the frame strap under the seat directly in front of the battery.

Locate & route the pink lead to Signal / For 2004 & later FXST/C/I The #3 cavity in the connector {39b} on the back of the speedometer. The socket terminal on the signal (pk) lead fits the #3 cavity.

Locate & route the Orange and white lead to power / Ummm.. it's saying for 2004 and later to adapt to the fuse block For earlier [ For 1996 to 2003 softail: locate the power lead (o/w) in the tail lamp pin connector {7a} under the seat behind the right rear corner of he battery.] "here you are looking to run it to a fused line, not directly to power/battery" I hope this helped.

SOURCE: I am replacing stock headlight

Use an ohm meter to verify that the black wire is indeed a ground (earth). Put the meter in R X 1 and touch either meter lead to the black wire and the other meter lead to ground. The meter should read less than one ohm.

Now, turn the ignition switch on and the headlight on low beam. Put your meter's function switch in DC VOLTS, 20 VOLT or greater scale. Connect the meter's black lead to ground. Touch either the red or the white wire with the red lead and see if you have voltage. Which ever wire has voltage is the low beam power wire. Then switch the light switch to HIGH beam and again check the wires, the "hot" wire is the HIGH beam power wire.

On your new light, you should have a wiring diagram telling you which filament is the low beam and which is the high beam. If you don't, just wire it up and flip the "high/low" beam switch and see if it looks right. If it doesn't, switch the wiring. The new light should have a ground somewhere as well. Since I'm not familiar with this particular light, the ground may be a body ground that relies on physical contact when bolted on the bike.

Good Luck
Steve

Good Luck
Steve