Headlights & Stator & Rectifier

[Crash4723]

I bought a 2008 Shenke 150cc scooter and what I noticed right off the bat is that the headlights were super dim at idle and not very bright when revved up. I rode it home (about 25 miles) and I also noticed that when I grabbed the brake the headlights became bright. I thought it was a problem with the ground so I traced & cleaned with a wire brush the negative lead from the battery, the wire to the frame, and the wire to the engine.

This did not resolve the issue. I know the headlights work off the A/C circuit and the tail and turn lights work off the D/C circuit. Now at an idle the headlights are off. When I take off from a stop sign the headlights come on but are very dim. When I hit the brake lights (While cruising at about 6k RPM's) the headlights become bright and stay that way until I come up to a stop sign again and then they dim and go off again. It seems that the only way I can get the headlights to come bright again is to hit the brakes when I am above 4k RPM's or so.

So where is the most likely spot to start diagnosing? I already ordered a new rectifier cuz they are cheap. Is it possible/likely that I have an issue with my stator? How do I even test my stator?

-Crash

[techie610]

I would guess on the VR.
And the only real way to test the Stator, is to replace it. :(

[techie610]

Also, I had a problem with my lights blowing when I revved the bike.
Turned out that my tail light had a short in the contact. That caused my head lights top blow as well.

[Crash4723]

So I have changed out the rectifier, removed the stator and cleaned it up, inspected it for broken or worn wires, and put it all back together. Still having the same issue. Last night while driving home my headlight, marker lights, tail lights, and dash lights were all dim. I grabbed the brake and it was like a light switch came on and everything was bright as I cruised across the bridge at 55 mph. When I came to the exit ramp and around a sharp corner letting my rpm's drop below 2k, the light switch went off again and everything was dim. Then as I cruised down the street I pushed my emergency flasher button and everything was bright again.

I don't know what else it can be. Anyone have any more ideas? Maybe another bad rectifier? A bad stator? Wired wrong? Maybe this scoot is just cursed.

-Crash

[DW]

I have the same problem when I use my turn signals. Started noticing it after I replaced the lighted mirrors with non lighted ones. However the headlights don't dim at all if I have the stereo amp on drawing 2 more amps. Could it be that a minimal draw is required to make the regulator work right?

[techie610]

I don't believe there is a 'minimal' draw requirement..
But with the statement of the stereo, I have to guess myself now.

Unless, you have a bad ground somewhere, and turning on the stereo might activate a new ground?.. Im kind of a little dumbfounded here.
If you have cleaned every grounding point, and filed of the paint, but it still does it, when its running, wiggle the light bulbs, pull them out, or twist them.
just be careful, as they get hot..
(^ Just so we can be 'Politically Safe.. lol)

[DW]

Could be because I run 35w bulbs instead of the 25w stock bulbs. However I never had a problem till I took the lighted mirrors off. The wife still has the lighted mirrors on her's with the 35w headlamps and no problems. But thats for another thread.

[techie610]

No, those bulbs wouldn't matter.
Could you buy new mirrors?

[Crash4723]

Well now I am going to add a little more to the mix. I intentionally drained my battery down to 11.5 volts by leaving the emergency flashers on yesterday while at work. They blinked for about 3-4 hours. Battery was at a solid 12.9 volts prior. When I took off from work the headlights were bright. As I pulled up to a stop sign the normal dimming would occur and then when I took off again they were all bright.

So why would the A/C headlights, tail light, and dash lights be affected by the amount of DC amps drawn through the system? Yesterday was the first time in a while I was able to maintain bright headlights and dash lights all the way home without fail. I am assuming the same about my tail light, but I'm not quite dumb enough to turn around and look at it while cruising down the road at 45mph.

[DW]

Sounds like a bad connection to your headlights that is resolving itself when you activate another circuit. Look for a pinched wire or bad connection. Wire terminals are often at fault but look ok at a glance. Thin gauge stranded wire can break inside the insulation leaving only a strand or two to carry all the current. Take the plastic off the headlight and move the wire harnesses around with the engine running and see if the headlights get brighter. Use a good piece of wire between a wires terminals to test a wires integrity. Logic can not be your only tool with these oddball circuits because when you do find the problem you will most likely say "go figure".

[techie610]

Well, I am baffled now.
DW has the last thing I would accept for a fault.
Sorry, I don't think I can be of any service. :l

[Crash4723]

I am going to tear into it tomorrow morning. I have a 2nd new vr on order that will arrive tomorrow as well. I know that the stator is doing a good job keeping my battery charged. The resting voltage is 12.9v. With the battery partially drained the headlights and dash lights act as I would expect them to, to dim at idle and to get bright when I take off and cruise, but this only happens when the battery is drawing amps to become fully charged. If I trickle charge the battery over night to 100% then the headlights and dash lights go back to extremely dim at cruising and off at idle.

Tracing wires and then replace the vr again tomorrow. Will post the results.

Thanks guys!

[Crash4723]

So I installed the 2nd new voltage regulator and now the headlights and dash lights stay on when I pull up to a stop sign, but they are about 50% of their potential brightness. They do not get any brighter when I rev up the engine. Still stumped. I am going to pull a voltage test coming out of the stator and see what is going on there. If the stator is producing the desired voltage prior to it running through the regulator then the only thing I can assume is that the regulator is screwed up.

[Crash4723]

Taking it to a repair shop on Saturday. I am out of options.

[DW]

https://lh5.googleusercontent.com/-pv6V1-cHA0c/UaaLwSQVnGI/AAAAAAAAAGM/Kk3mKgFokao/s1024/GY6Schematic.gif

As you can see, one wire from the stator (yellow) powers many of the lights (including headlights). From your description, you are getting an intermittent draw, dimming your headlights.

Since the headlights don't go out completely it is safe to assume that the yellow wire is intact and not grounding out. However, if the voltage regulator were leaking too much power to ground, it would cause the same issue. You stated that you replaced the regulator. In this A/C circuit the rectifier serves to dump excess power to ground, giving you 13VAC to your lights. If this fails, all the power goes to ground and can burn your coil windings in the stator.

There is also a ground screw on the stator that is subject to vibration.

[Crash4723]

Replaced regulator three times now. I am still stuck with the same issue. Headlight, tail lights, dash lights are at approximately 50% brightness. At idle I get 6.5v from the headlight plug, the marker light plug, and the tail light plug. At 3k RPM I get 8v from each plug. I am going to check the voltage from the yellow wire coming out of the stator going into the regulator and see what it is at. Any idea what it should be? Raw AC voltage from the stator at idle?

[DW]

It will vary with rpm's. Checking it at the headlight is the same as checking the yellow wire from the stator. I suspect the stator is your problem.

[Crash4723]

Wait a minute... The voltage at the headlight should be around 12v. The yellow wire coming from the stator is un-regulated voltage, it goes into the regulator (to be regulated to around 12v) then comes back out and splits to the lights?? Right? There's no way raw voltage is fed directly to the headlights.

[Crash4723]

Maybe I am confused with how and what the stator creates. I thought the stator created raw AC voltage, sent it to the regulator that in turn regulated it (for AC lighting) and changed it to DC for battery charging..

[Crash4723]

What was explained in the diagram makes sense though.. The auto choke is super slow in releasing and bringing the engine off high idle. If it is only getting 8v then that makes sense.. But I get 13.9v at the battery and I've never had the battery drain down, so I assumed the stator was working properly.

[DW]

Your right about the choke but mistaken about the stator. The stator has 3 separate coils that share a common ground. One coil powers the CDI with A/C and the voltage is regulated by the CDI. Second coil powers the head/tail lights and choke which are A/C (yellow wire) and the EXCESS voltage is then drained off through the regulator to ground. The third coil (white wire) goes directly to the regulator and is converted to D/C and regulated at 14.5Vdc to run more lights and gauges and charge the battery. So if you have one bad coil in your stator connected to the yellow wire, the other two circuits aren't affected.https://lh3.googleusercontent.com/-pv6V1-cHA0c/UaaLwSQVnGI/AAAAAAAAAGM/Kk3mKgFokao/w1024-h660-no/GY6Schematic.gifKeep in mind that the headlights and perhaps some running lights go through the high beam switch first so the wire is a different color at the socket.

BTW if you run the bike with the regulator unplugged there is no place for the excess current to go except through the bulbs. This is why blown bulbs and blown regulators go hand in hand.

Everything you ever knew about wiring gets thrown out the window on chinabikes lol.

[Crash4723]

lol.. Agreed.. But on my bike if I run the bike without the regulator I don't have any lights at all.

[qwertydude]

150cc scooters often run headlights as DC straight from the regulator. When you turn on the ignition but have the engine off do your headlights work? Or do you have to press the brake then they work? Also when you press the brakes do your brake lights work normally?

If you press both brakes does it go dim again? Without diagnosing this problem, constantly replacing regulators will do you no good. I'm betting the problem is miswired lighting. Wouldn't be the first time this happened.

Try unplugging both brake switch wires. Then connect them one at a time normally to see if any of those are causing problems.

If not then I would remove every external light bulb but the headlights. That means turn signals and brake lights.

If you unplug the turn signals and brake lights you're isolating the head lights from possible wiring problems from the brake lights which should show up as normal running headlights.

Also post a picture of the rectifier, we need to know what type of rectifier this is, 5 wire or 6 wire it might be able to tell us of the plug has been miswired.

Because the above diagram looks more like a 4 wire 50cc wiring diagram. The 150cc often has 5 or 6 wire regulators.

[Crash4723]

Well, the headlights, tail lights, and the dash lights only work while the engine is running. Brake lights, turn signals work off the battery without the engine running. The brake lights work perfectly, the turn signals work perfectly too. The wiring has not been changed since the headlight and tail light and dash lights worked properly, so I don't think it is a wiring issue.

The regulator is a 4 pin plug. I have three different varying size regulators that I bought from different suppliers, all with the standard 4 pin plug. The color coded wires match on each plug.

[qwertydude]

Keep replacing regulators then. If you don't want to do actual diagnosing work. You'll find the problem eventually when you just end up replacing every component you suspect might be the issue.

Diagnosing problems is a methodical method. I'm trying over the internet to help you, likely with a multimeter I could easily diagnose the problem in about 15 minutes. But it takes more directed and sometimes more tedious diagnosing procedure to guide someone through an electrical system.

But if you know more about the wiring system and know it's good 100% then why do you have electrical issues to begin with.

Like people here have said you replaced the regulator three times. Doing it a fourth time won't help. The only other two possibilities are wiring or the stator. If you're sure it's not wiring, and I can think of a couple wiring possibilities that can give you the symptoms you describe, then it has to be the stator. Do you want to risk replacing the stator and have the problem still be there? That's a rather costly diagnosing procedure. When the advice I gave to help diagnose is 100% free. Only costs a little bit of time and effort.

But if you know more than me...

[Crash4723]

Qwertydude, you don't have to be a smart ass about it. I answered most of the questions you asked. You asked if when I pressed both brake handles if the lights go dim again? My problem is that they are always dim. They never get more then about 8 volts at any given time. I have a multimeter, and I know how to use it. The stator is putting out about 15 vac at idle, 26 vac at about 3k rpm, this is of course with the regulator unplugged. On e the regulator is plugged back in my volts on the yellow wire straight from the stator stays right at a out 8 vac, each light plug stays at the same too.

You stated that most 150cc scoots come with a 5 or 6 pin regulator, but this is my 3rd 150cc in the last 4 years and all three of them came with a 4 pin regulator.

The headlights, tail lights, and dash lights all work off AC voltage. They do not work off the battery or DC voltage. They don't work with the engine off. The only things that work of the DC voltage, battery, and/or with the engine not running are the brake lights, turn signals, flashers, and horn.

Don't get me wrong, I Appreciate the help and advice, but if you're going to sling mud at me then thanks but no thanks.

[qwertydude]

It will be very hard to isolate the problem if the wiring system is still whole. You need to be able to 100% know every link in the wiring system is going where it should and the wires leading to them are a solid connection, believe me you might think pulling light bulbs is an unnecessary idea but a single miswired brake wire or light bulb can cause those symptoms. Unless you've physically traced every wire is going to it's proper destination you can't rule out a miswired wiring harness.

So if there's an alarm system you need to disable it by unplugging it completely. All the light bulbs it's a good idea to unplug them, this was actually advice posted by a previous poster. Basically if you have dim headlights you want to be able to isolate all the wiring going to just those headlights and light bulbs. Making it as simple as tracing one path, stator, regulator and headlight bulbs.

Draining the battery and having the lights temporarily restored also might still be a grounding issue. I would check continuity of the wires and connectors and just for good measure temporarily mock up a grounding probe. Then with the scooter running probe both sides of all the the connectors on the green wires of the now isolated headlights and also probe to see if grounding the heatsink of the regulators helps. This will determine if the ground is being lost anywhere, due to bad connections or even broken wires, as stated by previous posters. This is why you want to unplug all the rest of the bulbs so there's less to investigate if unplugging the bulbs doesn't lead to a diagnosis.

Not trying to sling mud but you seem very resistant to several people's good advice. This site is relatively new. So it's hard to really see who has all the real experience to give good advice. But the advice given is pretty standard, and even on this thread surprisingly consistent when it comes to diagnosing electrical problems. In this case have you done everything to isolate the problem and half split it to the actual component? Unless you pulled every bulb and removed all sources of extraneous grounds, and ground checked every green wire you can't say you have.

If you replaced the stator too that means you've replaced the regulator, and stator but still believe it not to be the wiring. That makes it difficult for me to believe you've done a wiring diagnosis. Next step if you don't want to do a complete wiring diagnosis, put a whole new wire harness in. You've already replaced all the other components already, and doing them multiple times obviously hasn't helped.

[DW]

Isolate the yellow stator wire by removing it from the connector. Start the engine and check A/Cv on the yellow stator wire make sure the meter has a good engine ground to the black probe. It should be something over 12v. If it tests good then pull all the bulbs that come on with the engine and unplug the regulator and auto choke and remote start if equipped. Now do a continuity test to ground on ALL the bulb sockets including the ground wires. If you have lighted mirrors, check those too and the often missed license plate bulb. With everything disconnected you should NOT have continuity on anything but the grounds.

[Crash4723]

I unplugged the entire stator 3 wire connection where it joins the wiring harness. The stator is putting out about 15 vac at idle, 26 vac at about 3k rpm. I will have time this coming weekend to isolate each bulb socket and wire. Until then I am riding the scoot to and from work, during daylight hours of course.

[DW]

I unplugged the entire stator 3 wire connection where it joins the wiring harness. The stator is putting out about 15 vac at idle, 26 vac at about 3k rpm. I will have time this coming weekend to isolate each bulb socket and wire. Until then I am riding the scoot to and from work, during daylight hours of course.

Is it safe to assume that you checked each stator terminal individually with the black probe to a good engine ground and the red probe on one wire at a time?

You didn't state which wires you tested and what results you got for each stator wire with it unplugged.

[Crash4723]

I only checked the yellow wire.

[jameshsmith324]

Can anyone answer this riddle. I am having headlight issues myself. I have a 2008 Vento Zip "Li" Two stroke. I turn key on. Start scooter: horn works, blinkers work. tail light works. Head light do not work or side, daytime running lights. What does work, is, when i flicker the bright headlight by pushing down.
What i have done so far to check problems:
1. clean the contacts in the right housing by throttle
2. Replaced main head light bulb and both day time running light bulbs.
3. Diagnosed wires from lights. they are good.

What i am not sure about is when i move the switch position for headlight, daytime running lights and in off position and nothing happened. When the motor is running the lights on the dash used to go brighter when i gave more throttle.

Could it be: a stator, contacts in right housing gone bad, Regulator/rectifier?

Please HELP!!!

[finaljudgement]

This was a great thread to read. An interesting and common problem, some really good tech advice, great diagrams, and a little drama. I hope you will let us know what the problem turned out to be when you finally find it. I am confident from your comments that you have the ability and persistence to do it.

Finaljudgement

[Kuzeblast]

I am having a cimilar problem, well not really, but I am not getting spark to my spark plug, on my gy6 150cc. We replaced the cdi box. Went over the wires and found nothing really wrong with any of them, it turns over, and all the lights work. The alarm works as well, just no spark, any ideas?

[carasdad]

I am having a cimilar problem, well not really, but I am not getting spark to my spark plug, on my gy6 150cc. We replaced the cdi box. Went over the wires and found nothing really wrong with any of them, it turns over, and all the lights work. The alarm works as well, just no spark, any ideas?
This link should help..I posted it in 2 other forums and it has been helpful to many.:D http://49ccscoot.proboards.com/thread/4666/easy-guide-spark-condtions

To the original poster of this thread...it sounds as if you have a short..where a hot wire is going to ground..:tup:

[tvnacman]

gee sometimes you need to start at a common base line .

John