Background: I have a 2000 Ultra and I just replaced the stator. Since I got the bike, it has run with the check engine light on. However, the bike does not give me a code (when I hold down the trip button and turn the bike on, all the modules say "CLR"). The check engine light stays on while the engine is running. The bike seems to run fine, but is sometimes difficult to start. I recently removed the Power Commander and that seemed to make the bike more difficult to start. The bike has just under 69,000 miles on it and the stator I replaced in August 2024 was the second time that the stator has been replaced on this bike. The first time the stator was replaced happened before I got the bike. The previous owner said he did not replace the voltage regulator (i.e., this voltage regulator is probably the original). I replaced the stator because the bike shut down on me during a ride and when I got it home the stator was only reading 8 volts a/c at 2000 rpms.

What I have checked already:

Battery terminal connections are tight - no play
When the bike is turned off the battery reads between 13 and 13.2 volts
The new stator, at the wires coming out of the primary case reads 50 volts a/c at 2000 rpms
The manual says that the voltage regulator on my bike should put out between 14.3 - 14.7 volts 3600 rpms. At the battery terminals, at best I am getting the multimeter to "flicker" between 14.29 and 14.3 at 3600 rpm.
The check engine light turns off after the bike is switched on but not started, then the check engine light comes back on when the motor starts and stays on after that

Would you consider this a bad voltage regulator? Is there a bench test for a voltage regulator? Could a voltage regulator cause the check engine light to come on but not give a code? Anything else I should consider?

Any thoughts / suggestions would be appreciated.

 

thats not a normal reading with the battery at rest.

 

If the battery is not brand new and it reads 13.2 volts ignition off, it is likely shot.. Brand new can read that high until they've been exercised a bit..

In order to dump codes from the ECM you need to short to pins on the diag connector and count the engine flashes.. Google it.. Don't remember the exact process.

14.29 and 14.3 are good numbers for charging.

 

On my 2002 ElectraGlide, I had a no code CEL appear. Checked all the code registers and found nothing. Found something online that suggested replacing sparkplugs. I did that and no more CEL.

 

Thanks for all the responses. Just want to clarify that the battery reads 13.2 after you shut the bike off and by the next morning it reads 13.05 and it holds at 13.05. The battery is about a year old.

Also, I did not get a code CEL, the bike indicated "CLR", which I believe stands for "clear" or no codes. I have not replaced the spark plugs yet and it is possible the spark plug wires are the original ones from 2000. I will replace both and post the results.

Thanks again.

 

Get the battery load tested. As stated with some time on it, after sitting it should be lower. One thing you can do is see how much the voltage drops when cranking. Should not be less than 9.5 volts.

Also changing plugs won't do anything. 2002 bike has Delphi EFI which ion senses through the plug. If yours is EFI, it's Magneti Morelli which does not sense the plugs.

I'll repeat your speedo does not dump ecm codes.. It only dumps speedo codes. Neither does an 2002 for that matter.. You have to short 2 pins on the diag connector and read the flashes of the engine light.

 

IMO -You have a 12 volt battery that is reading greater than 12 V system off. Could be your test equipment is a little biased.

Also, If you have an increase in measured voltage after startup the voltage regulator is dong its job.

The regulator is simply 3 diodes converting the AC voltage from the stator to DC voltage for the battery system. Either it works or it doesnt. loose a diode and it doesn't. I have had on 1 occasion where a regulator stuck on and overcharged the battery. In that situation it blew light bulbs.

 

Quote:

Would you consider this a bad voltage regulator?

The regulator shows: it can stabilize the volts within the 14's limit.

Quote:

At the battery terminals, at best I am getting the multimeter to "flicker" between 14.29 and 14.3 at 3600 rpm.

This is a steady 3600 rpm? And there is a flicker, meaning, it is jumping to those two numbers? Sounds like a faulty reg or low battery in the voltmeter.

Quote:

Is there a bench test for a voltage regulator?

I'll show you the loop of the electrical charging system to see who is good, who is bad.

1. 12,8v or higher is a well charged battery sitting static for a few days,
2. With key on, battery should remain at 12.8v. This shows a good battery with reserved PUSH. Push means volts.
3. Start engine, Battery should drop or make this load testing for the starter motor to occur, and drop in volts to 11.1v.
4. Battery recovers to 12.8v once engine starts, Battery shows good with lots of reserve to PUSH the starter motor over
5. Engine is running and clears the 12.8v to now read 14.4v. This shows the battery is well charged and no fault there. No fault at the stator or regulator.
6. Engine is running and 12.8v remain steady. This shows a bad stator.
7. Engine is running and shows over 15v. This shows a bad regulator.

Quote:

Could a voltage regulator cause the check engine light to come on but not give a code?

No and Yes.
Does this occur with the engine not moving, or once started, you ride away and it remains on?
Say it remains on while riding. This shows a wire disconnect somewhere, an open wire, a direct short blowing fuses, or a sensor out of spec.
Say it finally turns off once running a few miles. This might be for ABS to signal the tone wheels, or if no ABS, then might be for the power control signal off the tone wheels.

 

When I switch the bike to ignition, the check engine light comes on for a second and then goes off. Then when I start the engine the light comes back on and stays on while the engine is running.

I checked my fuses and they are not blown.

I did notice that my speedometer and tach did not do a sweep motion when I checked the codes. Not sure if that means anything yet.

 

A measured variation of 14.29 -14.3 is not a significant variation.
These bikes are definitely NOT sensitive to 1/100th of a volt.

This is likely a limitation of the meter, related to the meters' sample rate and the resistance of the contacts to the probes during the measurement.