Yamaha SR 125 _ Indicators driving me mad

20 posts / 0 new
Last post
Yamaha SR 125 _ Indicators driving me mad

Got an SR125 Yam, the indicators are blowing my mind,

they work when the key is turned on but the engine is not running,

they work fine when the engine is running but only on tickover ,

but as soon as you apply any revs on the throttle they just the stop flashing and then single flas every 20- 30 seconds if at all .

As soon as you let the revs drop off to idle , they kick in agian and flash correctly.

I have changed the relay

It is a brand new battery 

I have had the switch apart and cleaned it ..

So any ideas, 


Could it be regulator connected , if so how do I check / test that component .


All ideas welcom .




I have swapped the flasher relay  for a new one , but still the same , the switch has been removed and cleaned . So any ideas ? 

That sounds to me like you've got a slightly flat battery and the wrong rating bulbs. Or possibly the wrong rating battery. Check whether your bike runs 6V or 12V electrics, check what the battery voltage is, and check what the voltage rating on the indicator bulbs and flasher unit are.

Thanks ,  the battery is BRAND new and supplied as the exact part for the motorcycle YAM dealer supplied, and I checked it against the spec. It is fully charged and has a battery trickel charger optimiser on it . Have checked all the bulbs already and they are all 12 v and the part number stated as being the specs for the bike. The only thing that changes when the bike is reved up could be the charging rate, is increased, but why that would then kill the indicators is beyond me ...   So guess Im going to have to take it to the dealer and leave it with them ..  Its my sons bike, and want it ready for the new year ... so thought id try the forum ..  Thanks though,       

hi gaz its a posibility that you may have a faulty voltage regulator.you will need to check the ampage not the voltage it should run between .5 to 4ish amps at 5000 rpm anymore than that and that could be your problem regards

Hi CK42,    I have had the rectifier off and carried out the tests that the Haynes manual says to do that would indicate the diodes Health, they all pass, but that only tells me that they work in the correct sense .  Your suggestion now is the next option for me , but I am at a little loss on how I do that test , is it as simple as setting the multimeter to the 10 amp range , and then put the probes on the respective leads (Red and Black) on to the power cables leading to the battery and doing the run test ??     The rectifier plug has 5 wires, 3 x white and 1x red , 1 x black .   Thanks to you or any one else that can advise me, riding weather is gettong ever nearer ...  

To measure the voltage you touch the meter probes to the red and black wires with everything still connected up. This is "in parallel" - kinda piggy-backing on the system. To measure current you need to disconnect either the red or black lead. You then connect one of the meter probes to the lead, and the other meter probe to whatever the lead connected to (most likely the battery). The meter is now "in series" - it forms part of the actual circuit. Meters generally have an internal fuse to protect them when used like this. If you get a reading of 0, then it's possible that the fuse has blown, or never been fitted.

Incidentally,  I did have a problem on a bike once where the voltage at the battery DROPPED as the engine revs increased. This was caused by a poor connection between the reg/rec and the battery. The reg/rec voltage was always about 14, but as the engine revs increased and the current supplied increased, all this current being squeezed through the bad connection was losing more and more voltage, so the voltage at the battery dropped.

To rule out any strange things going on with the charging circuit and its connection to the battery, why not disconnect the red and black leads from the reg/rec to the battery. Now start and run the bike and see if the indicators behave any better.

Hi Tappy, funny enough, i started the bike before with the regulator unplugged and the indicators work perfect at any rev range, so guess Im getting a bit closer as it leads then to either power generation or rectification fault..    But Ill connect it back up and do what you have listed with the multimeter, so cheers for that too .Think I will also ask locally if anyone has an SR parked up for the winter that would maybe let me swap the rectifier over either mine to them or theirs to mine .. Thanks again .  

In that case do the following check with the reg/rec connected: With the engine running at idle, measure the voltage at the battery. Increase the engine revs slowly to 6k rpm, make a note of how the voltage changes. Now do the same test, but measuring the voltage across the red & black wires, as close to the reg/rec as possible. Again, note the results and bring 'em back here.  

Hi again Tappy, sorry for delay but wrk and weather .got in the way .   The details are below , hope they are clear as to what I did.  Thoght I needed to get a base line figure of the voltage without any draw or system so turned off all lights .  Then added in to the normal ride configuration of head light on and indicators selected on.     (and as usual rev increase from idle , indicators stop flashing ) I have given the range the multimeter fluctuated through top and bottom .   So hope you can help , Im now at the stage of taking it to the garage as my final plan ... although the cost of that may then outweigh the value of the bike anyway ...   Selected - Indicators off - head lights off  At Battery connection Idle tickover = 14.19v- 14.20 v 6000 rpm approx = 13.87v -14.04 v   At reg / rec plug break (reg side plug red / black wire) idle tickover 14.3 v 6000 rpm approx = 13.20-14.1 v   Selected- Indicators On - Head Light On At Battery connection Idle tickover =13.34 v- 14.10 v 6000 rpm approx = 13.71v (Indicators stop flashing but voltage remains static figure)   At reg / rec plug break (reg side plug red / back wire idle tickover =14.26v - 14.44 v  6000 rpm approx = 13.68v (Indicators stop flashing, voltage remains static ) Thanks    Gaz

Ok, Im now bald with pulling my hair out ..   Developments today . When the bike is warmed up , engine idle or running at revs, the indicators do not work , UNLESS !!!!!!!!  The brake is activated (either front or back brake) So long as the brake light illuminates with the normal lights on too ... then the indicators start to flash ....    Im having a nightmare ..   Think I have no choice but to put it in to a bike shop or auto electrical place .  

did any of this work? I am having the same problem..

Do you mean that your indicators are only working correctly with the engine off or at idle, and stop flashing when the engine's revving? Or a different problem? If the problem's the same, have you tried measuring the voltage at the battery, at several different engine speeds as I suggested?

Liona ess. Wow just realised its been a year , but no , still no resolution , but to confirm my fault for you just to be sure you do have exactly the same as me . So confirm, with the ignition switch on - engine not running .

  • Indicators work fine .

With Engine running at idle,

  • the indicators work fine

As soon as the engine revs move from idle speed either by using the throttle iteself , OR by turning the screw on the carb to increase the revs

  •  indicators stop flashing for 25-30 seconds, then flash once and then stop again. and the cycle then becomes unstable at best .

At one point pressing the brake levers would allow the indicators to flash for a few cycles then stop again. It is almost as if there is too much current / voltage being generated and by putting more laod on by the brake light being illuminated uses the excess , daft I know but hey ..  So The problem still exists im afraid . I have changed 

  • The relay
  • The Battery
  • Rectifier / regulator
  • the actual crank case with all the armatures in it.

We have carried out all the electrical tests that the Haines Manual says to do  We have checked all the bulbs for correct wattage  the bike has been parked up for a year with different things all being looked at. One time , there was no earth to the back lights or indicators yet the back / Brake light was still working hence why we now have individual earths for the indicators , just in case. Tappy , we will do the voltage measurement again on Wednesday and bring them back to this site , been a while since, but I seem to recall there was no drop when the revs increased, in fact  the voltage increased in output . In it all, the only thing that has not been changed is a whole switch unit that has the horn and lights , so my next step is to try and get a 3 position rocker switch to isolate the indicators from the rest in case there is some sort of current leak across the internal connections of the switch ... It will take a miracle im afraid  

You'd expect the voltage to increase, but only slightly. If it went far above 15V then that could be the problem.

Tappy I should have the voltages again by the weekend. Forgive me but how can there be excess voltage, what possibly could be the cause of that other than the windings, which have all been changed as an assembly.  Is there some sort of resistor that should be in the circuit somewhere that may have been removed by the previous owner ?  Thanks ,  this is really a challenge and very brain taxing ... 

I have a 2002 FZS 1000 which had LED indicators that worked fine. I replaced them with original bulb indicators and an original relay, but now the indicators are doing exactly the same as you mention by stop working as soon as the engine speed is increased. I have checked the wiring and all the connections which are fine. Maybe your bike also had LED indicators? I wonder if there are resistors somewhere in the circuit that would cause this? I read that by fitting resistors, the LED indicators would flash at the correct speed, but too fast without the resistors ???

Further checks show that when the engine is at idle the flasher relay gives an on/off output voltage of about 13v. When the speed is increased the voltage is obviously increased at the flasher relay. When it goes above 14v the flasher output side to the indicator lights goes to zero volts, so I expect it's the relay that is faulty or it's the wrong one for the bike. 

Replaced the flasher relay with the correct one for the bike and now works perfect. job completed...

Log in or register to post comments