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Ok heres a new one...

Customers 02 road star Silverado... 
Did oil change n other misc items.. 
I always check charging at battery when looking a bike over. Bike wasn't charging so did typical tests n found bad stator.. 
 Replaced stator n reg w oem.. Here's where it gets weird n I'm lost now.. 
 Stator unplugged n it puts out 60+ ACV all day long.. 
Plugged in n it drops to 11 ACV n only 12.4v or so at battery.. 
I've spent a month or more trying to find the problem.. 
 I've used 3 different regs now (OEM twice n a cheap Chinese) , I used a 4th one that is the mosfet type to bypass all factory wiring.. They all do the same thing. 
 I've pulled the stator n checked for pinched wires etc.. All perfect.. All ohms tests are perfect for stator , all wires to/from reg to battery ohm out perfect. Grounds are good, no burned plugs, battery voltage at red wires on starter relay.. Unplugged at reg gives me 60+ACV, battery voltage at unplugged reg... 
 Good battery
  Only additional load are two lights up front.. 
 So two key points .. 
Lose ACV plugged into stator 
Lose ACV plugged into reg
If I unplug either its good 
Wiggling wire harness n plugs no change.. 

I'm n 04 MMI grad . been self employed for many years. (Normal day job plus working on bikes at home, now 4 yrs just working on bikes) 
 Any n all ideas appreciated

Topic:

11 Comments

First thing, check your battery cables for resistance.
Here's what I use. Hope it helps.
https://cdn.shopify.com/s/files/1/1091/5694/files/fault-finding-diagram....
The comment about analog meters gives one pause.
https://cdn.shopify.com/s/files/1/1091/5694/files/diode-testing-guide.pd...

Nice flow chart.. There's a couple things on there I'll try today.. (Pertaining to the reg) .. Cables all show perfect continuity/ohms... Everything has voltage as it should that I can see... No loose unplugged wires that I've found (bypassed kickstand switch is only one unplugged) ...

Customer is gonna take it as is since he's heading home in a few weeks (new Zealand) .. So out here putting it back together n figured.. What the heck ill put in the new battery that I fully charged last night...
Its smaller but starts bike fine.. Weird tying is it actually charges at 12.7-13v .. (Fully charged Old battery stopped at 12.5v) .. So not fixed but might work ok for riding around a bit.. I told him to keep a back up plan in mind if bike won't start or shuts off on him....

WTF... Omen of a bike..

"The best way to test for shorts to ground is with a 12-volt test light. Sometimes an ohms meter will not pick up a short to ground. The light test is better.

Using a standard automotive test light, connect the ground clip to a good ground. Test the light by touching the probe to something positive such as the positive battery terminal. The light should light indicating you have a good ground. Now you are ready to start the test.

Unplug the regulator from the stator and start the motor. Probe each stator pin with the test light one at a time. If the bulb lights when connected between any of the stator plug pins and ground the stator is shorted and needs to be replaced.

If you get proper AC voltage and the stator is not grounded (no light) the stator and rotor are good. At this point you can assume the problem is either a bad connection between the regulator and the battery or the regulator is bad."
cycleelectricinc.com

How would it not show a short to ground ? All 3 yellow get OFL to ground n 1.1 ohms between them..
It puts out 30 ACV @ idle n 60+ soon as rpm's come up..
Highly unlikely I bought 4 bad reg's (OEM, 2 Chinese n a mosfet to bypass all factory wiring.)

If you don't have a short, you have a high resistance or a open. A bad connection or a cracked wire can given frustrating problems. If all components in a system are known good then the issue is in the wiring.
The old school check of pulling one fuse at a time to find a bad circuit is based on this.
http://www.roadstarmagazine.com/2002/07/troubleshooting-the-road-star-ch...

Lol all typical charging system tests I've done 100's of times as a tech... Every part I've checked shows correct ACV or ohms.. (Actually found that page long ago)
3 stator wires all ohm out @ 1.1 ohms (it's "cold" here right now)
All stator wires show 30 ACV @ idle n 60+ACV revved a bit (at stator plug and reg plug)
Stator wires are OFL to ground
All wires to n from reg show perfect continuity (.06ohm)
Cables ohm out perfect
Ground clean
Cables clean n tight
Battery replaced now (weird it actually charges a bit better w new battery 13v instead of 12.5v)
4 different reg/rec tried (all new, one OEM, 2 Chinese, one mosfet style) all show same results..
Unplugged 60+ACV (at both plug by battery or at unplugged reg)
Plugged in 11 ACV

Edwin you nailed it with pulling the fuses.. Pull the headlight fuse n it charges perfect... Now to find that short.. Dammit...

Lmao.. So first start up w headlight fuse pulled n it charged perfectly @ 14.5v or so... Messing around trying to track down exactly where the problem is n voltage just kept getting lower n lower till back to square one (even w headlight fuse out) ...
New battery it would atleast charge close to 13v.. Old battery back in n it goes to 12.8v or so (w headlight fuse pulled) ..
Maybe just getting to hot sitting here idling..

Well, that was fun. Don't be a stranger.

Lol customer took it home.. He's out in a few weeks for his home in Nova Scotia.. Maybe I'll see it again when he gets back next year..

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