Hello everyone. Been having an electrical issue with my bike. It's a 1998 Harley Dyna Wide Glide. Last season I had an electrical gremlin giving me starting issues. The bike would slow crank like a dead battery. The battery was new and fine. I would have to get on the bottom of the compression stroke in order for the starter to be able to crank and start the bike. The symptoms never changed unless the battery levels did. It never left me stranded so I left it till the off season. Started my bike in the middle of winter a few times to cycle fluids, symptoms stayed the same. The fist chance to ride I had... I went to start it and it wasn't getting power to the single fire coil. Removed every ground and harness connections (including starter and battery cables),and cleaned them all to bare metal and applied dielectric grease. No change in symptoms. After electrical checks I found that If I removed the "Lights" breaker the bike started fine.... and cranked strongly(improved a symptom). The head light is more than a season old from being new out of the box(non LED). The turn signals are all incandescent bulbs(no running light functions). the tail light is an LED Cat Eye style light. All lights function normally with the breaker plugged in, but wont start. Remove breaker and she will start strongly. There is a Blue wire coming from the breaker. I found it leading into the rear fender and cut it. It did not fix it. There is trace voltages on all connections that should be hot but they aren't buzzing my Power Probe with the red light and chime like it should.....Any ideas?! .....and sorry for the long read! I feel like there is a short to ground on a hot in the lights some where.

 

Measure the voltage at the starter motor terminal while trying to start, with and without the lighting breaker in place. Also, the voltage at the battery with everything off and while trying to start both with and without the lights.

 

Voltage supply isn't the issue. When I connect it to the Breakers it loses hot somehow. I spent all night going thru each individual Component, Connection and Etc.. All checked good. I completely replace the left Handlebar wiring harness and Switches tonight(no change). The power wire from the Main Breaker(the one fed by the battery) to the Ignition Switch harness shows hot(with audible alerts) at the breaker end of the wire, and hot(without audible alerts) at the other end of the same wire where it connects to the Ignition connector. If your familiar with Power Probes then you know what I mean. Now because it somehow loses power whilst still showing trace power it wont operate the Ignition Coil to fire the bike when cranking. However it will let every other function on the bike work. Now for what ever reason when I unhook the Headlight only... the problem goes away completely. Plug the Headlight back in and problem comes back. I completely disassembled the headlight tonight as well and it is immaculate inside and out. I re-scuffed all connections and applied dielectric grease before reassembling it. It's a standard Headlight(non-Led).

 

I will say, 9 out of 10 times we see these problems, the "good" battery is not good and the culprit. The lack of power to start the motor when the light are connected has me thinking you do not have enough juice. I agree with John CC's suggestions for checking voltage with and without the lights.

We like to turn these into moon shots, but again most times the battery is just shot. Good luck.

 

Obviously you don`t know what the cause is, so maybe listen to what people suggest.

This is a very simple circuit to diagnose, if you follow some basic steps.

Forget about the lites circuit for now, test one circuit at a time.

Charge the battery and have it load tested.

Once a known good battery is installed, read the voltage across the battery posts while the starter is cranking the engine.

What is the voltage reading?

 

New battery doesn’t alway equal good battery.