08 XB12XT Electrical Issues

[Wax]

My 08 Uly is having a few issues.

My CEL started coming on and off intermittently all year. The bike ran fine, but also blew 2 low beam headlights. I did notice one time that the CEL came on when I was on the highway and opened up the throttle all the way, it went off later after I slowed back down. This makes me think it is a VR issue. I was going to just replace the VR and hope the issues went away without doing any testing.

The last time I rode it (about a month ago), I rode to work (26 miles) and there were really no issues it seemed other than the CEL coming on once or twice as usual, then going off. However, after work my battery was dead. I got a jump and rode home no issues. This makes me think maybe my battery got fried by the VR if it's bad. Would my battery possible die from a bad VR? After I got home that day, I put my battery on my trickle charger. I put the battery back in the bike and it sat for 2 or 3 weeks because I was scared to ride it and be stranded somewhere with a dead battery without diagnosing it properly. The other day I fired the bike up (again it had been a charged battery, then sat for a few weeks) and it fired right up, so that makes me believe it maybe is not a bad battery and now I fear it's the stator. However, that one day the battery died I rode all the way home with no issues so it seems the stator was charging the battery.

The other day I finally decided I'd start figuring out what's wrong. I have the bike mostly torn down (seat, air filter and intake assy, side scoop off, VR off but still plugged in). I already took off the ground and cleaned it up, it looked fine, but I may still do the ground wire mod and run a ground cable from the top engine bolt (where that steel cable bridge is) unless somebody knows a better spot.

Can anybody direct me to step by step instructions on how to test the VR and stator (and anything else I should)? I have been looking through multiple forums and all the info seems kind of choppy and not just a "do this this and this". Here's my thought process if anybody can help:

1. Take battery to auto parts store and have it load tested.
2. Test VR - How do I do this? Which wires do I test? Do I test with the bike running or off or both? I have a multimeter, but I'm not sure what to test and what readings I should have for voltage, resistance, etc. nor am I sure what setting to have the multimeter on for each test.
3. Test stator - How do I do this? I have seen some info on testing with the bike running and measuring resistance. What wires do I test, how do I test it, what should my multimeter be set to, and what should the readings be?

Is there anything else I should do? I want to ride but I just can't find the time to dedicate to this project, especially when I'm not quite sure what to do exactly.

BTW I also plan to do a mod to extend the VR out from the cylinder regardless of if I get a new one or not, read that somewhere on this forum.

Thanks in advance for any help.

[Griffmeister]

Sure sounds like a VR, but most important is to have a meter and check things out first. Here's the issue, bad connections/ broken wires can mimic a bad VR. Also, many times the VR does not go totally bad and there really isn't a way to bench test the VR itself, it's more like eliminate everything else. On the plus side, the charging system is pretty simple with very few components.
First, all connections must be clean and tight. Luckily there's only four places to check; battery, frame ground (next to fuse box which also has 30Amp battery fuse), 77 connector and 46 connector both of which are behind left air scoop. Next check the stator which is single phase on the 08's. Disconnect stator plug (46) and check each pin to ground first, there should be no continuity. Second check across the two pins, there should be 0.1-0.3 ohms resistance ( some meters don't do such a great job so you may not be too concerned if it's slightly different). Last, stay on the two pins but put your meter on AC volts. Run the engine at 2000 rpm and you should read 40-56 VAC output from the stator. If you do all this and everything checks out good, then it pretty much points to the VR. You can reconnect the 46 plug, set your meter to DC volts and monitor the battery before and after starting. With everything off, the battery should have about 12.8 VDC. After starting the voltage should read about 14.5 VDC with the engine running. If it's below 13 or over 15 you have a definite VR problem. If it seems okay but you're blowing headlights, the VR could still be bad and causing occasional spikes. If you don't have 12.8 VDC to start with at the battery, you need to pull the battery, put it on a charger, then have it load tested properly for the type of battery you use. Hope this helps.