Flickering lights

[dvdcrdl]

I have a 2009 Toyota IQ 1.0. I put a led kit about a year ago. I didn't have any problems until a month ago.
Sometimes in traffic, when the car is idling, the odometer display, low beams and position lights flicker. 
An auto electrician said it was the led kit that needed to be replaced, so I replaced them. The problem was not solved.

Then I went to another workshop and they told me it was the alternator, so I replaced it.  Now the problem has subsided but it is still present especially for the internal display.  Thank you in advance and sorry for my English, I'm from Italy.

[flash22]

Did you have the Battery tested ??

[dvdcrdl]

4 minutes ago, flash22 said:

Did you have the battery tested ??

Yes, but the problem isn’t the Battery😫😫

[flash22]

I would be checking the grounding points and looking for signs of corrosion in the fuse box

The yaris and auris suffer with flickering gauges - not a 100% sure if the iq uses an Eco Run convertor or it's done by a Power management module

[dvdcrdl]

7 minutes ago, flash22 said:

I would be checking the grounding points and looking for signs of corrosion in the fuse box

The yaris and auris suffer with flickering gauges - not a 100% sure if the iq uses an Eco Run Module or it's done by a Power management module

Ok I will check them. I also thought about the led lights, in particular I saw that a position light has burned out, could this be the problem?

[dvdcrdl]

On 11/16/2020 at 2:03 PM, flash22 said:

I would be checking the grounding points and looking for signs of corrosion in the fuse box

The yaris and auris suffer with flickering gauges - not a 100% sure if the iq uses an Eco Run convertor or it's done by a Power management module

Ok I checked the grounding points but they are in good condition. But while I was checking I noticed that the charge indicator on the Battery is transparent, this means that the Battery needs to be replaced. I don't know if this indicator is reliable and if the Battery is the cause of my problem. Help me please😭

[flash22]

Green or red is ok if its black the Battery is dead or dying

A test with a proper Battery tester is needed not just a multi meter

[dvdcrdl]

On 11/17/2020 at 8:34 PM, flash22 said:

Green or red is ok if its black the battery is dead or dying

A test with a proper battery tester is needed not just a multi meter

I have other updates. I went to the workshop and they told me that a worn out Battery cannot cause flickering at idle. They also reset the ECU.  In summary: led lights replaced, alternator replaced, control unit reset and the problem was not solved. Interior and exterior lights in my car flicker with the engine warm at idle. 
I do not know what to do.. As always sorry for my English

[flash22]

leds replaced ?? Have you fitted any bulbs or replaced them for Led bulbs ? If so put the normal bulbs back and see if the problem goes away

[Mooly]

I agree with flash22 and I actually suspect you might be chasing a non existent problem... meaning if the original fitment of all the bubs and lights was OK then the car is actually working as intended.

LED's have no 'thermal inertia' like a filament bulb and so any rapid variation in LED current (LED's are really current driven rather than voltage driven... a subtle distinction) will show as a visible change in light output (flicker). In a bulb it goes unnoticed because the filament can not respond quickly to the change.

Battery condition can have an impact because as the Battery ages the internal resistance increases and that will allow the 'ripple' seen across the Battery to increase. That does not mean the battery is defective, it is just enhancing the visible effect of the ripple. Seeing a difference when the alternator was replaced can also be explained away by such things as very slightly differing output voltages which give a relatively large change in superimposed ripple voltage depending on the battery condition. 

The bottom line is that LED's need to be fed from a stable and constant current source and so that usually means extra circuitry needs to be 'designed in' to achieve that. For panel and instrumentation lights that simply means a stable voltage regulator should be included in the design.

[dvdcrdl]

12 hours ago, flash22 said:

leds replaced ?? Have you fitted any bulbs or replaced them for Led bulbs ? If so put the normal bulbs back and see if the problem goes away

 

8 hours ago, Mooly said:

I agree with flash22 and I actually suspect you might be chasing a non existent problem... meaning if the original fitment of all the bubs and lights was OK then the car is actually working as intended.

LED's have no 'thermal inertia' like a filament bulb and so any rapid variation in LED current (LED's are really current driven rather than voltage driven... a subtle distinction) will show as a visible change in light output (flicker). In a bulb it goes unnoticed because the filament can not respond quickly to the change.

Battery condition can have an impact because as the battery ages the internal resistance increases and that will allow the 'ripple' seen across the battery to increase. That does not mean the battery is defective, it is just enhancing the visible effect of the ripple. Seeing a difference when the alternator was replaced can also be explained away by such things as very slightly differing output voltages which give a relatively large change in superimposed ripple voltage depending on the battery condition. 

The bottom line is that LED's need to be fed from a stable and constant current source and so that usually means extra circuitry needs to be 'designed in' to achieve that. For panel and instrumentation lights that simply means a stable voltage regulator should be included in the design.

First of all, thanks a lot to both of you!
A year ago I mounted 6000k LEDs and they worked well for 9 months, but after these 9 months this problem arose. An auto electrician replaced them with another less powerful LED kit but the problem was not solved. Then I went to another workshop and they told me it was the alternator so I replaced it with poor results. A few days ago I returned to the same workshop to say that the problem has not been solved and they have reset the control unit. In these days I have noticed that the problem has not been solved but I have understood that it only does it with the engine warm at idle. The idle also drops below 800 rpm when the engine is hot, while when it is cold it is just below 1000 rpm, is it normal? 
Can a low idle cause flickering lights?

Thanks for reading and for your interest, from Italy! 🙏

[Mooly]

Low idle speed reduces the frequency of the ripple voltage because the alternator is not turning as fast. The alternator output is not pure DC but consists of three overlapping 'half sine' voltages. At lower speeds your eye can detect the change in brightness as the voltage changes. Its a bit like watching old films. You can see the low frame rate as 'flicker'. As frame rate is speeded up the movement in the picture becomes smoother because your eye can not then follow the very rapid changes. Same with the alternator.

The alternator produces the three sine wave voltages shown in the lower left of the diagram. Each is 120 degrees apart. The lower right shows the rectified voltage (by the diodes in the alternator). You can see it is not pure. The 'load' in this example would be the Battery and car electrics. The alternator is 'pulsing' the Battery with those peaks and that is what you see as ripple. 

 

 

 

 

[flash22]

Put some halogen bulbs back in her, do you have auto lights ?

[dvdcrdl]

15 hours ago, Mooly said:

Low idle speed reduces the frequency of the ripple voltage because the alternator is not turning as fast. The alternator output is not pure DC but consists of three overlapping 'half sine' voltages. At lower speeds your eye can detect the change in brightness as the voltage changes. Its a bit like watching old films. You can see the low frame rate as 'flicker'. As frame rate is speeded up the movement in the picture becomes smoother because your eye can not then follow the very rapid changes. Same with the alternator.

The alternator produces the three sine wave voltages shown in the lower left of the diagram. Each is 120 degrees apart. The lower right shows the rectified voltage (by the diodes in the alternator). You can see it is not pure. The 'load' in this example would be the battery and car electrics. The alternator is 'pulsing' the battery with those peaks and that is what you see as ripple. 

 

 

 

 

Thanks, I will try to clean the throttle body (I don't know if you say that in English) because in addition to the flickering of the lights at idle, there are sometimes strange vibrations especially when I engage reverse gear. Perhaps the two are related. 

14 hours ago, flash22 said:

Put some halogen bulbs back in her, do you have auto lights ?

Yes I have. I have already tried it, for the low beam no problem but for the position light I was unable to turn the connector.  
 

I'll let you know.

[dvdcrdl]

I did some checks before taking it to the workshop to clean the throttle body.  When there is flicker the engine is usually at 500 rpm is this normal?  Is the idle so low in your IQs when the engine is warm?

[Mooly]

500 sounds to low. 800 to 900 would be more typical on a modern engine and this may actually increase to more like 1000 rpm in response to additional loading such as switching A/C on or heated window etc.

 

 

[dvdcrdl]

40 minutes ago, Mooly said:

500 sounds to low. 800 to 900 would be more typical on a modern engine and this may actually increase to more like 1000 rpm in response to additional loading such as switching A/C on or heated window etc.

 

 

Ok thanks, here is a photo of the car at idle when the problem arises

 

[Mooly]

Hard to say from that as the dial hasn't really got the resolution to make an accurate assessment... visually perhaps a little low.

The idle sped once the engine is up to temperature should be pretty consistent day to day (all other things being equal such as what you have turned on) and so if some days it is OK and others not then that suggests a problem. 

Maybe others with a similar dial could see how it compares to theirs.

 

[flash22]

Looks about right for a 1KR 3 pot, if you raise the revs does it still flicker ?

[dvdcrdl]

1 hour ago, Mooly said:

Hard to say from that as the dial hasn't really got the resolution to make an accurate assessment... visually perhaps a little low.

The idle sped once the engine is up to temperature should be pretty consistent day to day (all other things being equal such as what you have turned on) and so if some days it is OK and others not then that suggests a problem. 

Maybe others with a similar dial could see how it compares to theirs.

 

Yes, I will search to see if the minimum is marked like this on the other IQs.

 

1 hour ago, flash22 said:

Looks about right for a 1KR 3 pot, if you raise the revs does it still flicker ?

No, when I raise the revs the problem disappears immediately

[flash22]

That is usually an alternator regulator issue unless there is an issue with the sense wiring

[dvdcrdl]

3 hours ago, flash22 said:

That is usually an alternator regulator issue unless there is an issue with the sense wiring

Yes. On Monday I'll take it to the same workshop where the alternator was replaced and I'll let you know. Thank you all for the support!

[dvdcrdl]

Cleaning of the throttle body made and also adaptation with poor results.
  The displays and idle lights still flicker and I honestly don't know what else to look at.
  Summing up:
  - led kit replaced
  - alternator replaced
  - control unit reset
  - clean throttle body
  - readjustment done

  Another thing I have noticed is that the problem is mainly with the car leaning downhill

[Mooly]

You have chased lots of possible scenarios for this but have you done as flash22 suggested earlier and put it back to original fitment (and wiring if anything was changed/altered) and then see if the problem persists or not?

Unless you do that you have no idea whether you are chasing a real issue or not.

Looking at it from a different angle it is still possible to come to a definite conclusion 'why' the LED lights flicker but you need the necessary diagnostic skills and test equipment to troubleshoot it (circuit and component theory and equipment such as an oscilloscope) as you are looking for clues to a symptom that may or may not be related to an actual problem.

 

 

[dvdcrdl]

12 hours ago, Mooly said:

You have chased lots of possible scenarios for this but have you done as flash22 suggested earlier and put it back to original fitment (and wiring if anything was changed/altered) and then see if the problem persists or not?

Unless you do that you have no idea whether you are chasing a real issue or not.

Looking at it from a different angle it is still possible to come to a definite conclusion 'why' the LED lights flicker but you need the necessary diagnostic skills and test equipment to troubleshoot it (circuit and component theory and equipment such as an oscilloscope) as you are looking for clues to a symptom that may or may not be related to an actual problem.

 

 

I agree. This morning I took the car to the workshop. They will keep it for a couple of days, I'll let you know. In my opinion, the only thing left to check is the serpentine belt, its tension and its pulleys.