I just got a new wiring harness for my 75 XLH because when I went to go investigate my tail lights and turn signals that stopped working I saw the wires were all frayed from rubbing on the tire. But when I hooked everything up I still don't have any tail lights or turn signals. Does the bike need to be running for them to work? I have a few pics of the new harness. I have the schematic but I don't know if maybe a circuit breaker is blown or something. I am getting power to the wires.

 

The bike doesn't need to be running for the taillight and turn signal lights to work, but the ignition switch needs to be on and switched to the "lights" position if your switch has separate switch positions for "run" and "lights" like my '82 has.

I don't have a wiring diagram for a '75 but I have diagrams for '59 to '64, and '79 to '83. I checked a few of them, and all the ones I checked show a green wire going to the tailight. That green wire should have +12 volts on it if the "lights" switch is on. It feeds power to your taillight (not the brake light). I'd start with that one and get it working before trying to figure out the turn signals.

If that green wire has +12 volts, your taillight bulb is good, and the taillight assembly is grounded correctly, the taillight should light up.

 

My '82 schematic has a circuit breaker just for lights, my '69 schematic doesn't. If you have one for your lights, I'd check it.

 

Thanks for taking the time to look this up for me Yellowstone Kelly! I have the manual and looked at the schematic and found that red wire that I spliced in from the bottom plug is the power for the tail light switch. It only has power when the brake pedal is pushed down. The green wire going to the tail light does have power to it with the key on the second position so I am not sure what is going on but I will check the lighting circuit breaker and the accessory circuit breaker next. Thanks!

 

Yep, the red wire to the taillight is for the brake, green wire to the taillight is the taillight (or running light).

Does the brake light come on when you push on the brake? If neither the brake light or taillight works, I'd check to make sure the taillight assembly is grounded well where it bolts to the bike.

To check it, I'd pull off the red lens and touch a jumper wire from the outside of the bulb socket to a good ground on the bike, with the lights turned on.

You're using a dual filament 1157 bulb, right? At least that's what both my bikes use.

 

HI Kelly, No, the brake light does not come on when I push on the brake pedal but the red wire does light the tester when I step on the pedal. My tail light and both turn signals don't work either so i'm hoping it's the breaker. Yes I do believe I have 1157 bulb in there I will take the lens off and check that also next time. Thanks for your help! I need to get the lights working because I just put new pistons and rings in last fall but haven't started it up yet so I can break it in properly.

 

Sounds to me like your brake light socket may not be grounded and as for the other lights, you mentioned the turn sigs don't work and are hoping it's a breaker.

Turn sigs are powered by the same breaker as the brake lights. The brake light power comes from the Accy. breaker and power for the tail light (amoung other things), comes from the lighting breaker. If the lighting breaker is bad, your head light, speedo, high beam ind and tach lights would also not work. So if the bike is wired according to the factory diagram, it's probably not a breaker. Unless of course those other mentioned lights are all not functioning, then the breaker is a possibility.

You have brake light power, so you should have turn sig power. And if any lights up front work, such as the headlight, tach, high beam ind or speedo that tells you again that it's not the breaker.

Grounds are very important and bonding wires need to be in place and in good condition to be able to complete the circuits on different areas of the bike such as in the case of the handle bars. I'm not sure how many bonding wires are on the bike.

Where ever you suspect you may have a ground issue, take a jumper wire and clip it to the battery neg. Then touch it to the light socket outer case for example, to be sure that the socket during the test is in fact getting a good ground. Because most items get their ground from the frame, those bonding jumpers need to be there to conduct back to the battery neg.

 

+1 on all of the above.

 

Kelly, I know you covered a lot of that stuff already, but I just got ta ramblin'.

 

i got an old iron head too,and brother this thing has been rode hard and put up wet for real.im slowly tryin to bring it back.