I recently bought an '08 Street Bob and it has some (seemingly not uncommon) voltage problems. At first, it would run until it got hot and the engine light would come on. If I stayed on the throttle it would run, but the speedo would start to fluctuate from actual speed to -0-. If I were to let off the gas completely, it would no longer fire (as evidenced when I pulled in the clutch, but would refire when pop-started with a little gas). If I kept the tiniest bit of throttle on it, it would remain running so that I could sit at a stop without it dying. It threw P0563, which is high voltage. So I changed both the battery and the regulator, Now it throws the P0562 code (low voltage). I trickle charged the new batt to 12.4v and now the engine light AND the battery light came on. The Diagnostic on the P code later displays "Pn" but shows nothing. The S codes state "none" but then gives me "Pn 68921-07" which is an obsolete Turn Signal Module (TSM) PN and all searches simply say no match found. After some exhausting research, that PN was replaced by 68925-07 "Turn Signal Security Module" or TSSM. Additionally, the "SP" codes also say "None" but displays "Pn 67478-046, which again, comes back with -0- results. I confirmed that there is actual low voltage at the batt with the bike running. I don't have a tach. but it should peak out at around 14.5 volts. I am only getting 11.9 volts with the bike running. That batt floats back up to 12.2 volts when I shut it down but has depleted a few tenths of a volt. I suspect it would draw down below operating thresholds if I rode any distance with this condition. I have a TSSM module on order. All the grounds need to be checked I suppose as well. If anyone knows how to find the upgraded part to the 67478-046 (whatever that is...) I would appreciate the info,

 

A charge of 12.4 volts is too low. Not by much, but it should be at least 12.5
Get the battery load tested. And, as you mentioned, check those battery cables, especially the ground. These are basic steps that should be done before buying parts you don't need.

 

You need to change the stator.. Run the stator tests. Bet you find coils grounded.

 

Yeah, the battery is just 2 weeks old but that doesn't exclude it. I'm waiting for a full day of rain here as the summer heat is at its peak right now. Drives me nutzo having sweat stinging my eyes and fouling my glasses every minute. Riding season doesn't get started in earnest here until October-November. and goes thru June. July thru September can be brutal here.

 

Oh, and the trickle charger has the batt up to 12.9v now

 

With the charger connected and on it should go to 14 volts then drop to about 13.2. if it's a smart one.

 

Yep. Check your stator output. If the stator checks good, check your voltage regulator. Keep in mind that if your stator is good, and your regulator goes bad, it can damage your battery by overcharging it.