Flickering lights

[dvdcrdl]

I have an update: I have noticed that these electrical voltage drops at idle become much more noticeable when there are passengers in the car, therefore when there are higher loads.

[flash22]

Higher loads ? It should not make much difference to the electrical system, A high load on the electric system the rpm should rise to compensate,  With the wipers, heater, rear defrost and a/c on you should see the idle rise

If not there is an issue with the sense wiring

 

looking at the wiring diagram, the only things left to check is the current sensor (also has a temperature sensor) on Battery and the power control ecu (this commands the alternators output)

i have the documents if required

To see what the Battery sensor looks like. Google 28850-40010 check to make sure the plug is secure and doesn't have any signs of water ingress or corrosion

 

[dvdcrdl]

On 12/5/2020 at 8:34 PM, flash22 said:

Higher loads ? It should not make much difference to the electrical system, A high load on the electric system the rpm should rise to compensate,  With the wipers, heater, rear defrost and a/c on you should see the idle rise

If not there is an issue with the sense wiring

 

looking at the wiring diagram, the only things left to check is the current sensor (also has a temperature sensor) on battery and the power control ecu (this commands the alternators output)

i have the documents if required

To see what the battery sensor looks like. Google 28850-40010 check to make sure the plug is secure and doesn't have any signs of water ingress or corrosion

 

Thank you!

Here are the errors indicated by the diagnostics:

About P1602 i find this:

OBD II fault code P1602 is a manufacturer specific code that is defined by carmakers Volkswagen and Audi as “Engine control module (ECM) – supply voltage low from battery”, or sometimes as “Power Supply (B+) Terminal 30 Low Voltage”, and is set when the PCM (Powertrain Control Module) detects that the Battery current being supplied to the PCM when the ignition is switched off, is below a minimum allowable threshold.

Any modern PCM, also known as an ECM (Engine Control Module), is a complex computer that contains a variety of voltage regulators/stabilizers, current converters, driver circuits, and several types of memory, all of which are involved in controlling, regulating, and monitoring hundreds, if not thousands of functions in a modern vehicle.

 

[flash22]

That makes sense the power management isn't controlling the throttle, the codes are Toyota specific, I will look it up shortly as I'm not in front of my main pc atm

[flash22]

The ECM stores DTC P1589 if the ECM or other components are replaced that require the yaw rate and acceleration sensor to be calibrated (deceleration sensor 0 point calibration) and calibration is terminated or the vehicle is driven before calibration is complete. This could well be caused by the power issue

[dvdcrdl]

3 hours ago, flash22 said:

The ECM stores DTC P1589 if the ECM or other components are replaced that require the yaw rate and acceleration sensor to be calibrated (deceleration sensor 0 point calibration) and calibration is terminated or the vehicle is driven before calibration is complete. This could well be caused by the power issue

Thank you very much. So the only things left to check are the Battery current sensor and the Battery that maybe needs to be replaced. Do you agree?

[flash22]

Battery sensor or the power management control ecu, if the car cranks over ok i doubt it's the Battery

Part number is listed above for the Battery sensor (Hint.  28850-40010)

 

[dvdcrdl]

On 12/12/2020 at 1:56 PM, flash22 said:

Battery sensor or the power management control ecu, if the car cranks over ok i doubt it's the battery

Part number is listed above for the battery sensor (Hint.  28850-40010)

 

Ok I had thought about the Battery because in the previous photo you sent me, for the P1602 error it says Battery deterioration. What does "cranks over ok" mean? Sorry but I can't understand from the translator.

[flash22]

Does the starter motor turn the engine over ok ?

P1602 can also be caused by a faulty sensor or Power Management Control ECU

 

OBD2 codes are diagnostic aid they are symptom not a cause

[dvdcrdl]

5 minutes ago, flash22 said:

Does the starter motor turn the engine over ok ?

P1602 can also be caused by a faulty sensor or Power Management Control ECU

 

OBD2 codes are diagnostic aid they are symptom not a cause

Yes, when the car is cold it does not take long to start and in any case always on the first attempt.

Ok thank you, another question: is the replacement of the power management control ECU a plug & play? Can I do it alone?

[flash22]

There is nothing specific in the documentation, I would check the Battery current sensor first

[dvdcrdl]

3 hours ago, flash22 said:

There is nothing specific in the documentation, I would check the battery current sensor first

Ok thanks tomorrow I'll take it to the workshop and they will check these two components. Do you think the problem is one of these two? Are we on the right track?

[dvdcrdl]

2 hours ago, dvdcrdl said:

Ok thanks tomorrow I'll take it to the workshop and they will check these two components. Do you think the problem is one of these two? Are we on the right track?

I forgot to mention that this morning I drove with the OBD, this is a graph where the engine rpm are in red and the ECM voltage in green. In yellow I have circled the moment when the problem occurred.

In the second photo there is the same graph without zoom.

[stemon]

Hi, as you have suggested it could be the Battery sensor , Disconnect the 4 pin plug ( im sure it had 4 pins), With this disconnected the alternator will act like normal and not keep cutting the voltage while driving. Mine had a crack in it and monitoring the voltage it would be very erratic from 14.3v to 12v while driving for split seconds.
It should only cut the voltage when the Battery is fully charged and there's no load as far as im aware.

Ive left it unplugged on the 1.0. Ive also done the same on my 1.3 stop start as it disables the stop start system which i didn't like.

I guess i should add Doing anything i have suggested is to be done at your own risk, Ive had mine unplugged for over a year now with no issues.

[dvdcrdl]

3 hours ago, stemon said:

Hi, as you have suggested it could be the battery sensor , Disconnect the 4 pin plug ( im sure it had 4 pins), With this disconnected the alternator will act like normal and not keep cutting the voltage while driving. Mine had a crack in it and monitoring the voltage it would be very erratic from 14.3v to 12v while driving for split seconds.
It should only cut the voltage when the battery is fully charged and there's no load as far as im aware.

Ive left it unplugged on the 1.0. Ive also done the same on my 1.3 stop start as it disables the stop start system which i didn't like.

I guess i should add Doing anything i have suggested is to be done at your own risk, Ive had mine unplugged for over a year now with no issues.

Thank you very much! Today it is still in the workshop, they told me that they check these two components. Tomorrow I will update you.

[Fenrisúlfr]

Are you sure you are chasing a actual problem? 
around 500rpm idle is normal, and the alternator is not spinning fast enough then to provide full power. Some displays, lights and stuff like that will dim a little when idling. 

rev your car over 1000 rpm, and the flickering should stop. As others have said, LED is much more sensitive then filament bulbs.

To me atleast, it sounds like you have tossed a bunch of money out the window.

[dvdcrdl]

I'm happy to tell you all that after about 1 week of testing I finally solved the problem. In the workshop they checked the power management control ECU and the Battery current sensor and they worked correctly.  The only thing to check was the Battery, you won't believe it but it was about to leave me. I replaced it and now after many kilometers I can tell you that everything works perfectly. For about 2 months the battery status indicator, also known as the "Battery magic eye", said that the battery had to be replaced but I did not pay much attention to it because the car started up without problems when it was turned on. I want to thank each of you for the many information and the passion you have shown you have. I hope to help you too here in the forum. I wish you a Merry Christmas from Italy!

[74hct04]

On 12/14/2020 at 5:36 PM, stemon said:

Hi, as you have suggested it could be the battery sensor , Disconnect the 4 pin plug ( im sure it had 4 pins), With this disconnected the alternator will act like normal and not keep cutting the voltage while driving. Mine had a crack in it and monitoring the voltage it would be very erratic from 14.3v to 12v while driving for split seconds.
It should only cut the voltage when the battery is fully charged and there's no load as far as im aware.

Ive left it unplugged on the 1.0. Ive also done the same on my 1.3 stop start as it disables the stop start system which i didn't like.

I guess i should add Doing anything i have suggested is to be done at your own risk, Ive had mine unplugged for over a year now with no issues.

My current/temperature sensor seems to be working well but also has a crack in it (in the soft potting compound). I've tried to repair it with MS polymer seam sealer (Liqui Moly Liquimate 8300) but we will see if it adheres to the potting compound...

The part number for the sensor is 28850-40010.

[74hct04]

A visually-similar sensor (albeit different part number and for a different range of cars) with cracked potting compound (see fifth photo):

https://www.aliexpress.com/i/1005004064055132.html

I certainly wouldn't buy this for my Avensis, if I owned one!