I have a 2004 VL1500 Intruder. The battery will not keep a charge, I did install a new battery thinking that was the problem. However, it seems that there is a constant drain on the battery from an unknown source. I can remove the battery, charge it on the bench and then install it in the bike, then two days later the battery is dead again. Could this problem be in the front turn signal lights. With the battery removed and the bulbs removed I have continuity between both the bulb contact points and ground, no matter what position the turn signal switch or the hazard switch is in. Since these are dual filiment bulbs are they meant to be on as running lights all the time? All systems seem to be working normal when I do get the bike running. Last comment, this bike only has 5000 KM, I had it shipped from Alberta Canada to Florida wheer there is actually a riding season. Sincerely, Steve

SOURCE: battery does not hold charge new battery fitted

Sounds like a charging issue. First check all wires and make sure they are clean and making good contact, then check for proper voltage at the battery. I ride a harly so I don't know the exact voltage to look for but it most likly is around 13V at the battery if it isn't you need to look at your voltage regulator and stator.

SOURCE: how do i get to the spark plugs on my 2001 Suzuki VL1500 Intruder

you have to take off your chrome cylinder covers.back one on the left front on right.they are in there.

SOURCE: 2002 suzuki intruder vl1500 not charging battery

Check the voltage across the battery with the engine running - it should be greater than 13.5V. 
If less, then you have a failure in your charging system, either the stator and/or the Rectifier/Regulator. 
See this personally authored diagnostic guide on how to determine which part is defective. Also has a recommendation for excellent replacement as opposed to std OEM. 
http://www.triumphrat.net/speed-triple-forum/104504-charging-system-diagnostics-rectifier-regulator-upgrade.html

SOURCE: 1992 Suzuki Intruder, starts and runs fine, but I

sounds like you poped a fuse have you pulled them to check them all out,,, you may have a main fuse blown

SOURCE: Rear tail light does not turn on.1998 suzuki 1500 intruder

It mught be the bulb that needs replacing or else check the wiring to the bulb for continuity in case there is a broken or snapped bit.If you have a voltmeter then you can test the voltage reading at the point of contact..Sometimes rust builds up and a simple cleaning would solve this.Hope this helps.