Step 1. First things first, load test the battery. Most places like Auto Zone will do it for free. Even if it measures over 12.5 vdc it can still be bad under a load. Battery is typically rated at 19 amp hours and 270 Cold Cranking Amps (CCA).

Start the engine and measure DC Volts across the battery terminals, the regulator should be putting out 14.3 - 14.7 vdc at 3600 rpm and 75 degrees F.


Step 2. To check the regulator unplug it from the stator. Take a test light and clip it to the negative terminal of the battery and then touch first one pin and then the other on the plug that goes to the regulator. If you get even the slightest amount of light from the test light the regulator is toast.

To do this with a meter which is more accurate: black lead to battery ground, red lead to each pin on the plug, start with the voltage scale higher than 12vdc and move voltage scale down in steps for each pin. Any voltage is a bad regulator.
You may get battery voltage on all three pins on the newer 3 phase regulators.
The no voltage is for older type regulators with diode indicating the diode is bad and the regulator needs replacing.


Step 3. On the other part of the disconnected regulator plug. Set the multimeter for Ohms x1 scale and measure for resistance across the pins of the stator. You should read something around 0.1 to 0.2 ohms for the TC88 32 amp system.


Step 4. Then check for continuity between each pin on the plug and frame/engine ground. The meter needle should not move (infinite resistance)(digitals will show infinite resistance) if the meter needle does move (indicating continuity)(digitals will show some resistance), recheck very carefully. If the meter still shows continuity to ground the stator is shorted (bad).


Step 5. Set the meter to read A/C volts higher than 30 volts (the scale setting for voltage should always be higher than the highest voltage you expect or you may fry the meter). Start the bike, and measure from one pin to the other on the plug (DO NOT cross the multimeter probes! - touch them to each other). You should read roughly 16-20 vac per 1,000 rpm.


Step 6. If the battery was good under load test, if the stator is NOT shorted to ground, and the stator is putting out A/C voltage, then the regulator is bad (most likely even if if passed step 2).


Generally the following is true:
Check your owners/service manual for the system amp output for your bike.
22 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.2 to 0.4 ohms.
32 amp system produces about 16-20 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.
45 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.

Also see here...
Charging System Flow chart - Harley Davidson Community (http://www.hdtalking.com/electrical_and_lighting_systems/6367-charging_system_flow_chart.html)

Dear Glider,

thanks for such valuable help.

However with your post you raised a doubt in my mind.

In Step 2 you are writing about connecting a test light to the negative terminal of the battery to touch each pin of the regulator after that. My negative terminal of the battery goes to the frame and I don't think it will allow a test light to shine no matter where I will connect it to, except to the positive terminal of the battery. Is there somehting I don't understand ?

With my ****ty little multimeter I can't measure the stator to have anything else than no resistance. Infinite resistance between any of the two stator terminals and the frame.

I can't do the test with the running motor because it's late here and my kids are sleeping. The thing which already happened to me on another bike was that the connection regulator - stator was bad. The connectors don't really inspire me much confidence. Is there any way to check that ?

Thanks a million
Fatboy92
The regulator

Fatboy92

In Step 2 you are writing about connecting a test light to the negative terminal of the battery to touch each pin of the regulator after that. My negative terminal of the battery goes to the frame and I don't think it will allow a test light to shine no matter where I will connect it to, except to the positive terminal of the battery. Is there something I don't understand ?

Yes there is, by connecting to the negative battery post (ie. ground) you are checking for voltage at the regulator plug pins doing this. It sounds a bit backwards but it is in fact correct. If there is voltage at the pins, it usually indicates a bad bridge rectifier in the regulator. The diodes in the regulator will allow current flow ONLY in one direction when operating correctly and if you detect current with the above process, it indicates the diodes are bad in the regulator.

Well thanks Glider, I have learned a lot by reading your tip.

My problem is however solved. AS I wasn't so sure about my understanding of the subject, I went to see my mecanic and he found it in two. The plug !!!! The regulator plug to the stator was not plugged in correctly. I had checked it, but it turns out that the rubber part sticking out under the cylinder has grown. Goodness knows how HD can install such rubber (rubbish). Now the plug doesn't fit any more. The bike is 15 years old and the plug just won't fit !!! I find thisa little irritating.

Anyway. My problem being solved I'll stick around your forum, because I find a lot of nice people seem to post.

Had I been a little closer we could have rode together, but who knows one day.



Holger

Glad you found the problem in any event. The older evo's had this problem, you are not the first to experience it. There is a clip on the market that will keep the plug connected and will not allow it to disconnect from vibrations, you may want to look into that.

http://www.jpcycles.com/groups.aspx?LID=a6eb303a-01d9-475b-9cc8-968a2f68a239&DID=1047e9e6-5126-464d-a9a1-c0a73e8765a9

Glider,

OK. On my way home tonight, my "check engine" light came on, and the voltage on the meter dropped to battery level (somewhere between 11-12 volts). I made it home, but the voltage was dropping all the way (not charging).

Once home, I checked for regulator bleed back and get 11.5 volts on either pin. Bad regulator, right?

Then I checked the stator leads. 1xohm on the VOM gives me a dead short (0 ohms resistance) on either socket, and same across the sockets. Bad stator, right?

Going to AC and starting the bike, I get about 22 Vac at 1,000 rpm with the voltage rising as I increase the rpm. Will a grounded stator put out AC voltage?

At this point, I think the weekend's activities are replacing the stator and voltage regulator. Your thoughts?

TQ

Your findings sound about right. The voltage output indicated doesn't necessarily mean a good stator. They have been known to show voltage and not put anything back into the battery. Sounds like your problem is two fold.
It's a good idea to replace both whey you have a problem in any event. Usually if the stator is changed, the regulator goes belly up shortly after. They can be very misleading sometimes in the diagnosis.

Glider,

When I drained the primary chaincase oil, it smelled burned. Popped the cover off, pulled the clutch, drive gear and chain off and then pulled the rotor off. THREE of the stator coils were burned with the one in the center of those looking completely fried (see the picts.) Had a similar problem on my '91. I guess these things happen!!

TQ

That's the first indication of a bad stator if you smell the oil and it smells burnt. Usually ends up in a change of stators and while you're at it a regulator too.

Where's the pics? :D

Glider, i am not familiar with this system. Other than the previous findings, i checked for vac from stator. And i believe i have a 3 phase system... i have a square plug with three pins. 06 model. i have as follows 16volts on top left and bottom left pins, 16 volts on top left and bottom right, 1.3 volts on bottom left and bottom right. this is all at idle and all values raise when i accelerate except for the last. So i think i have a bad stator and bad voltage regulator.. Im a little disgusted, this bike has only 20,000 miles and was bought in feb. 06... I wonder if hd will help out. I have no problems replacing this myself, i am a auto mechanic and have a bike lift at work, but it would be nice to get it covered under a goodwill warranty.Anyway does my findings seem accurate.