How To Test A Regulator Rectifier (Motorcycle) 

Get your multimeter here: amzn.to/3xg1olF

I did your test with 2 regulator both look good with the test, but one does not load my battery on the bike, and the other one does so this test does not always give you the right conclution. so I think you need to test the power it sends to your battery as well, when revving over 3000 rpm to be sure.

Guys, stop showing this test on the internet, or at least mention the fact that it could be irrelevant in some cases like mine. For example, I had a very old regulator rectifier (exactly the model from this video from a 2009 Yamaha FZ6 S2) that passed this diode test. But, when checking the voltage on it with the engine on, it wasn't charging enough. It was barely 12V on idle and 12.8V on high RPM. I also checked the stator and it was good. So, after I changed the regulator rectifier, everything was good, charging according to the service manual. So, the regulator rectifier might pass the diode test, but that doesn't mean that it works properly. The ultimate test is measuring the voltage on idle and on high RPM by connecting the voltmeter directly on it's + and - connectors. Exactly the way it's mentioned in the service manual.

Running this test, 1 of the phases seems to be bad. But with the bike running, the charge at the battery is ok, over 13v at 3000rpm, 15v at 5000rpm or more. What does this mean? My lights, horn, etc don't seem quite right, although it all works, and the battery after a ride sometimes is fully charged, sometimes (most times? Is at 12.7v...

My pass test but readings are lower. 4.6. With running engine charging shows 16.2 volts. Too much. . Is regulator faulty or else?

I don't know my bikes issue. The stater I tested the pins and they all passed both the ohms and current. The battery is 40 days old. Yet I have to use a charger to charge it. When I rev bike the voltage doesn't change on battery. Which means its not being charged but rectifier looked ok with the pin tests

Nice and clear. I've tested mine after a charging issue, one way its showing ~.5 on all three pins, reverse is 0. However the negative is only showing ~.1 on all three and also 0 reverse. Does this indicate a faulty rectifier?

Hoping you can help me, electrics not my best thing, im autistic, could you help me with this on my 2001 fazer1000 please, my readings are higher than yours but there's electrical fault with my bike. Bike wouldnt start the other week, then exhaust went bang fire came out, then charged battery 3hrs trickle charge then still woulnt start, then got it started but didn't sound right. Then started ok few days later, fitted new chain sprockets but smaller rear a 39 rather than the 44 so thought this reason why speedo cutting out needles bouncing all over place when went out for a ride 1hr, so ordered speedo healer but not fitted yet. Went out for ride on 14,10,23 for 1hr 30 mins, had lights on for half my ride then 40 mins from the end i was causing 60ish then bike trying cut out 3times them speedo cut out, so turned lights on took it easy for 15 mins before going fast then seemed ok, next day 15,10,23 started bike twice, in the day while waiting parts, got the multimetre you have now to test it once off but before that, bike running ok 5mins then speedo died then funny noise from bike so turned off, then tryed start it then dead, could I have problems with my battery or starter motor or both? Or somthinking else? Connections seem ok on regulator rectifier not burnt out as i was asked check as normally electrical backfires due to regulator rectifier faults, so 636 , 620 then 636 on my test like you did, everything else same as your test on other tests, but 1st tests were higher as above but my bike not 600 like yours its a 1000 fazer 2001. Not sure what to do next, not checked other electrical fixings yet, was hoping be regulator rectifier then just east fix but now im totally lost where else to check, was my bike supposed to take higher reading than yours? Dont really know what to do but want learn how fix it myself. If you can much obliged, cheers

Well that checked the diodes, and thank you for that! But I don't think it tested the regulator function at all.

So helpful and easy to understand. And figured out my rectifier is toast. Thanks man. Legend!

Just measure voltage? This diode check don’t mean Jack

+haha, same system or regulator type as you have hornet 600f my one is reversed, Its shot. Where put possitve to possitive, and then chek the other 3 at the botton I am getting a reading of 4.4 on all of them. hahah.

Hi. I have a question that i hope you can answer. I checked my rectifier and followed your procedure and my rectifier seems fine and working. The problem with my bike is when engine is off the reading is 12.5 to 12.7 when i start the bike and in idle the reading goes up to 13.7 but when i rev it to around 5k rpm , it just drops to 13.2 and back to 13.7 again when going back to idle. I always recharge my battery recently because it keeps getting drain. what could be the problem? Is it my battery or stator? Thanks

777th like =) Great video man! I've been in electrical for awhile (DIY only non profressional). I love tseting and diagnosis, but those of us that have multiple projects; we forget these simple pieces of information. I remember what it was, but took a minute to fully comprehend the functional purpose of the rectifier. Excellent video!! Informative. Articulate. Excelling hands on. Makes me wanna go in garage and dismount some rectifiers and test. 😂

Great video. 2 years on and it's still helping people. That's the sign of a good video. Thanks for this. Easy to follow and we'll explained. I tested mine as I think its broken, I got a reading both ways, that suggests it's dud. Ordered new one. Hopefully that'll fix my bike issue. Thank you for this video. 💪

Pass test. But reading i 4.6 ... Yours was 5.6.. Still good or readings to low?

I manage to fix my problem after looking at your post on youtude. Thank yiu so much.

Thanks for explaining R R UNIT VERY SIMPLE WAY THANKS A LOT

How much/ what span is ok on the reading as it flucurates? eg. reading on mine 0.498 0,512, 0.517 is that ok?

I have a grizzly 660 rectifier it passed diode but one of the legs was .48 the others .515 it didn’t work could this be why it didn’t charge as I replaced with another reg and all was good ?

I have a 2013 kx450 and I’m reading .527 across all 3. And reverse bias test is good. Does that mean it’s good ? Or those numbers are too low

I just followed your instructions. In my rectifier i have values around 470. Is that ok or it must be around 520?

Thank you very much my friend god bless you see you

When I use forward positive bias I get reading just shy of average in the .47 then .49 and on past node .51

Thanks. Helpful. Simple explanation.

Thanks for this. I've seen a few motorcycle reg/rec units and they never seem to label the terminals or wires. Even on yours, I couldn't see a + or - sign. Not quite sure why they do that. Labeling would make testing and fitting them much easier. Also, are reg/rec units interchangeable between different bikes? eg if you took one off a Honda mc and used it on a Suzuki one, could it be used on both bikes? Reason I ask is that I have an old bike I'm having trouble locating the correct reg/rec unit for so may have to use one off another bike.

my charging system on my 2013 ultra cvo shows only 13.4 volts while riding. Is this a problem

What is the lowest the reading should be? I was informed it should be 0.45 at the lowest.

Sir my rectifier showing forward bise only from one side Does it faulty ? Actually my bike not charging battery

Gracias gran video. Saludos desde Honduras. Nica bike.

Thnks bro, straigth to the point

Thanks a lot👍👍👍

Im getting a reading in the part where I shouldn’t . That means my rectifier is bad ?

Mine is 4.25 and climbs to 4.35 after three mine is hot on startup cooking the frame before the motor gets warm is it a rectifier or stator ,bike charges fine

You look like a stripped down version of henry cavill aka superman

Great video mate. Some confusion for me though - I have the exact same looking rectifier (Tourmax SH683-2) but my red and black leads are the two outside terminals on the bottom row of 3. How do I test this type of configuration? Thanks.

hah i have exact same as you but I now seem to have neg bias, so its all back to front, so I am taking that as my regulator is screwed , yes ? and thats with my new regulator which has now only done 100 miles, it was putting out over 20v before it blow out the dip beam and stopped.

this test does not work on my 07 triumph regulator.negative bias shows 1.7 on new regulator from ricks motorsports.

This video is old now, but it's exactly what I needed. My DR650 has been draining power for a few months now and instead of firing the parts cannon at it, I tried various ways to narrow down the draw. I first charged the battery and tested the voltage, then let it sit a couple hours and it was lower. I unplugged the fuse to my heated grips and charged/tested again, still losing power. I did the same for the stator, but it kept happening. I also tried messing with the ignition key as people say it can have issues, and removing it to charge/test, but it wasn't the issue. I took off the R/R and tested it just now like in this video, and I am seeing power across two of the three contacts in the reverse polarity configuration.

When i did the forward/positive bias test it showed no reading for me. Is this a sign that the regulator is faulty?

Very helpful (many thanks) but this only confirms the rectification side of the RegRec - this will not confirm the regulator side of the RegRec ie charge rate/under or overcharging. Current needs to be put thru it and output tested also.

When testing mine is testing the opposite, putting positive on the left top and negative to the other three is giving me around .4 for each. And OL the opposite with positive on the top left and negative on the other three. Why is this

thank you for your explanation.! I follow you with measuring as you do in the video and I measure... 558-557-1162 zero 554-556-002 zero. So i need a new regulator?

Thank you for dumbing it down so I can understand what and why.

I have a lexmoto urban, ive been told this could be my issue (sensor faults even after replacing sensor. Causing starting issues) can i still test without starting my bike?

Hello i was checking my voltage regulator and on the forward/postiv bias on the negativ wire it showed 0 on all 3 pins and when i did it on the postive wire it showed 448 442 451. My question is do you think that is why my atv does not start?

my regulator give me 4.5 for each , that's good?

Thank you so much! This and the stator vid. was just what I needed. I have 08 fz6 that has been giving me a bit of hard time. I think mine has bad ground somewhere thou. It runs fine for min. and then starts to run like crap and go completely dead no dash lights no nothing. I go to start it again and a good fully changed battery go’s completely dead by just hitting the starter button. When I did the stator test I noticed the the negative side of the battery was totally hot. Still working on it but very much appreciate the easy to understand videos!….

Well done mate - spot on. Thanks from Oz.

All there is is 3 wires coming out of mine , so unfortunately not helpful

thanks brother

Hi, getting a reading of 4.1 on all where yours is 0.5 My battery is not charging it stays on 12v when tested running, do you think this is the fault?

Could it fail and charge less than 12v?

So the last two you did mine are the opposite. I'm guessing that means mine is not working lol cheers for this video definitely helped me to understand when I'm rubbish at electrics 😮

Upload more videos about motorcycle electrical diagnostic. :)

So I did this test as you instructed and I get a .510 to a .514 reading in both positive and negative bias so my R/R is bad then correct?

Simple and clear, perfect for any of us with no previous idea, thank you 👍

The black wire on my regulator is negative ground power source.

Hi I just tested my rectifier as in your video and I'm getting a reading of around 2.6 on each of the phases is this ok or not? Thanks james

Yes but you only checked rectifier not regulator.

how to measure voltage AC ripple? How much the maximum tolerance?

Thank you so much for this video man!

Rectifier wires on my 01 Yamaha R1 getting super hot. Probably needs to be replaced. This will confirm. Thank you.

Just to be sure: If this test comes out as it should. Can I completely rule out there is any problem with the rectifier?

I‘ve got a Honda CB600F Hornet PC34. Sometimes it doesn’t start except if I jumpstart it, so I replaced the battery. And it worked for the last few days. Yesterday as I was riding I had to accelerate more than usual for it not to stall. Suddenly it just shut off. The battery was showing around 9 Volts. I jumpstarted it again, drove like 200m and it died again. Any idea what it could be ?

I have had to replace my battery multiple times this year. The battery goes dead and will no longer charge. (Dead cell I assume) I have a 6v system on a 1986 yamaha tt350, which has only a regulator. The regulator has a single wire coming out and is grounded to the frame. Can I do the test you performed on such a regulator Cheers :)

Hello, Nice vid. I have a 82 Suzuki GS 750, I just replaced the stock R/R with a made in china R/R & it's doing the job. I see these units all over the web, with different labels, I suspect they're from the same company, in china. I just found & bought a Nos 1982 Suzuki R/R in the box. I'm inclined to replace the made in china unit, & install the Stock unit. What do you think is the #1 reason, for failure? Thank you

Thanks for the video. Very easy to understand and follow. I’ve been having issues with my battery holding charge that I suspected it was simply not holding the charge anymore but after replacing it with a new one, I’ve had the same issue. After doing a Neg/Bias on the Neg/Terminal testing one of the nodes, I got a voltage reading which shouldn’t as with the other two nodes. I bought a new R/R to replace it.

Big help mate been having issues with my bike not holding charge ive replaced the stator start relay,flasher relay starter motor didnt think of the rectifer but just xhecked and mine only hitting 0.0023

Obtained a new rectifier from eBay for my 97 Kawasaki KLR650 ...The Diode test only works on negative ground to 3 stator terminals, but is Open on the battery terminal connection of rectifier in both directions. Not sure if I want to test n my Motorcycle (but might) because it is not giving me the testing results I expected. ... so still studying. Thanks for lesson.

Hey my bike died and is stator or regulator. After watching this video I'm assuming it's regulator because on the positive bias I'm getting. .506 .507 and the final one is reading 000 does this mean it's bad for sure? Also the negative test also failed on two of them.

Hey how you doing, question, my 2008 yamaha vstar is having problems with the charging system, i took the rectifier out and it has 6 pins connector and the bike has 5 pins connector, how's that possible? Thanks

red to Pos+ 3green wires to stator, and black to ground

What about the wiring ?

Superb... thanks

In a diode,check the dmm (digital multi meter) is showing you the voltage drop across a foward biased junction. Some meters produce enough to faintly light an led, but if not will look like a bad junction, just something to keep in mind.

Hi, thanks for the video. My readings are .485 across all three. Your readings are over 500. Any advice? TIA

Just saved me a good £100 having to put my bike in the garage. Bike started cutting out on me the other day and battery kept dying. Just tested regulator and it's not giving any reading of one of the pins. Ordered one for £14.

Thank q so much sir

Hey so my regulator has 6 prongs on it. It’s a ninja 250r. Would the test be the same with the additional prong?

Wouldnt a MOSFET reg/rec show an open line on the Forward Bias due to the switches inside but still be in working order? I appreciate this is for YOUR reg/rec, after reading the comments. But nowhere else do you state this is a test for non MOSFET/only for your reg/rec.

how to change it in the xt 660?

Why don't you show how a bad one would look, that would be useful for all DIY mechanics. Show how a good one looks and a bad one.

👏🏻👏🏻👏🏻

should there be resistance between + and - ?

Good informative one. Thanks. Keep that way!

Loaded and to the point, good tutorial Mate 🤙🏼 Is there simple way to test CDI and Coil?

Perfect explanation. Thank you!

My readings are all around .630, what could that mean?

Excellent! My recitifier is shot! Thanks

excellent video , well explained ! got a 2001 r6 , found a burnt wire to my rectifier , bike been running fine until warm then feels weaker . Battery now wont even charge from wall charger ! Hoping my rectifier and stator are ok and its just a burnt plug . Got new plug ordered now need to test the rectifier as youve shown

How to identify output point and also how to identify positive and negative terminals

Easy peasy.

Super+++++

Awesome tutorial. I just checked it on my dr650. Nearly identical. I have a question I tested stator plug it is reading about 1.8ohm testing the phases. The manual says 0.5 to 1.5 ohms is the good range. I tested the phases to earth and they came back correct. Any ideas

This is exactly the knowledge I was seeking!! Thanks!

its good

Can a positive battery cable that made contact with the frame, blow out a rectifier?

Thks four your excellent video just a question my PiaggioZip 2T all the bulbs headlights and rear all blow in same time what you think this can be the voltage Regulator thank you

Please man I need help My positive bias is... .120 And on second test Forward positive bias is .. .516 as your video demonstrated . So that means I have a problem???? I had two battery destroyed the batteries got big and rounded egg smell etc.. Now I order a new rectifier regulator and the measurement is also .120 and .520 ... as the old one.. Not sure now what is my problem as I was convinced that it was the rectifier problem .. any advice please