Hi everyone. I'm new to the forum, but I've owned my 73 XLH for four years now. It's a constant struggle with this ironhead and I've gone through many rebuilds. The latest is a total overhaul of the electrical system. Forty years hasn't treated her very nicely, but neither have any of her previous owners.

There were many splices that went nowhere, larger AWG cable going to smaller AWG where it shouldn't have been, and just a tangled mess of wires including connecting things that shouldn't have been connected. Honestly, I'm surprised it ran after pulling everything apart and doing the majority of the work these past few weeks.

I've stripped all the old wiring out, resoldered the connections inside the handlebars, replaced all old 18AWG with 14AWG (I had a spare roll lying around) and anything that carried a noticeable amount of charge got 12AWG (voltage regulator/gen/ignition coils-->breaker, horn, etc)

I've done away with the turn signals and used the attached wiring diagram to fit my bike. This is a Late '72 early '73 model (not the same as the late '73's to 84's I think). I also did away with the Speedo/Tach light combo. This is a very stripped down, but still very detailed diagram of what is going on in the early Sportsters.

I need help with the starter relay though. It was originally wired all crazy, and was bypassing the relay entirely. So I may need a new relay if it was wired that way due to it failing. But for the purposes of the diagram, someone please check my work so that I'm not putting out incorrect information. I've labeled the diagram for the relay and the points of connection. It has four, but the original diagram only calls for three.

Also, how do you test the circuit breakers (32,33,34) and relay to see if they are still working or are fried with an everyday voltmeter?

Attached is the original OEM wiring diagram and my MODIFIED wiring diagram.

 

Update: Got some input from an engineering friend. Said the relay does need input from each side for the coil to push the magnet. Neutral, which would be either the 12V orange lead or ground?

 

Terminal 1- from battery (B) terminal on voltage regulator
Terminal 2- to starter solenoid
Terminal 3- from starter button
Terminal 4- Ground

Looks like the box that says "frame" means the wire runs through the frame, those wires are not connected to the frame.

 

I got the starter relay working after hooking terminal 4 up to the 12v lead, it was smoking when it was grounded. I'm not sure if I damaged it though because I am having some other issues as well.

I have my biked hooked up exactly as the diagram with no D. signals shows (my second post), except for the terminal is now hooked up to 12v lead.

My 12v lead is no longer showing power. I'm not sure if the circuit breakers are fried or the relay is fried both or neither. How do you test them?

Is there a flaw in my wiring diagram that I haven't picked up?

The taillight stays on as if the brake is on constantly. I've checked both taillight switches for power by disconnecting them but the light remains on.

 

My final version, all wiring worked out, had a short in the wire going from coil to points, once that was solved everything worked out fantastic, here is the final version of a good wiring diagram for those of you that have nixed the turn signals like me.

 

I do not understand why I can't view the wiring diagrams on this page can someone help?

 

Atlas Mick, Thank you for your hard work that went into this drawing. I'm currently rewiring a 74 XLH with an aftermarket factory loom. I'm trying not to have to use the factory starter relay (because of size) and am wanting to use one of the small black cube style relays. Any reason not to do this?
Regards, Steve