Charging stopped due to system malfunction

[Rakesh Suresh]

Please make an oscillogram and show the result (photo) when connecting the D15 connector to the heater and when connecting this resistor* between +12V and the RMI signal.

Before connecting d15


After connecting d15


Video showing this
View attachment 20241030_174313.mp4

 

[asavage]

It appears as if you plugged in D15 to the heater, but didn't disconnect the 10k load resistor when plugged in, which is what I would have like to see.

 

[Rakesh Suresh]

It appears as if you plugged in D15 to the heater, but didn't disconnect the 10k load resistor when plugged in

Correct, I did not disconnect the resistor when I connected d15

 

[alflash]

This is what we know now.
1. According to https://www.myrav4ev.com/threads/charging-stopped-due-to-system-malfunction.2692/page-7#post-32100 the heater can work using control from an external simulator (NE555).

2. Now we know that the control signal from the PMC ECU without connection to the heater, but with an external load resistance (10 kOhm) is quite adequate.

3. The control signal from the PMC ECU when connected to the heater looks only like a "trace" of the correct signal. https://www.pravda.com.ua/news/2024/10/31/7482262/ Perhaps this is somehow related to such an input circuit LIN Transceiver (attach.) of the RMI signal located on the heater board.

4. Oddity/misunderstanding/questions.
Why does the control signal from the simulator only slightly reduce the amplitude when connected to the heater. And the signal from the PMC ECU is completely suppressed when connected (both with and without additional resistors).

p.s. Inside the Transceiver, the RMI signal input is connected to +12V via a current source and a diode (and possibly another resistor and diode).

 

[Rakesh Suresh]

It would be useful to determine (photo) the nominal value of the resistance that is connected to pin 3 of the NE555 microcircuit on the simulator board. And determine what its other output is connected to (to GND or to +12V).

I think you forgot to link the photo? I didnt fully understand your question, but here are some details that may be helpful.

Details of the NE555 board: https://www.amazon.com/gp/customer-...ef=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B018INS9QM


Resistances:
VCC to GND - 1.5K
VCC to OUT - 0.86M
OUT to GND - 0.85M

Here is a close up pic of the timer

 

[alflash]

Shall we check the heater control when connected with an external 2kOhm (not 10 kOhm) resistor?
Note: On the board, the generator output is connected to 12V via a 1.5kOhm resistor (152) and a LED.
The previous photo shows the diagram of the input circuits of the LIN transceiver RMI signals.


Attachments

 

[Rakesh Suresh]

Shall we check the heater control when connected with an external 2kOhm

Same behavior as earlier, although the amplitude is a bit higher. https://1drv.ms/v/s!AoMSicNQxi7y5y2rIktK4-8Ykyym

 

[Rakesh Suresh]

Is there any value in testing by connecting pwr directly to 12v battery positive terminal. That is another difference compared to the simulator.

 

[alflash]

Same behavior as earlier, although the amplitude is a bit higher. https://1drv.ms/v/s!AoMSicNQxi7y5y2rIktK4-8Ykyym

Are the oscilloscope probes connected to an external resistance?
What is its resistance value?

I have never directly connected the supply voltage to the information inputs. And I do not advise others to do this. Cancelled due to misunderstanding of the question, sorry.

In addition, high voltage at the RMI input is when heating is not needed*.
And this is shown in the form of oscillograms with a correct cabin heating system (https://www.myrav4ev.com/threads/charging-stopped-due-to-system-malfunction.2692/page-2#post-31850)

*For example, when the outside temperature is higher than the required/set one.

 

[Rakesh Suresh]

Are the oscilloscope probes connected to an external resistance?
What is its resistance value?

It's 1.98K. Yes, probes are connected to it.
Should we go even lower on the resistance in the next test?

My earlier question was if we should connect the pwr to positive terminal to rule out the possibility that ecu isn't able to supply enough current to pwr, but given pwr doesn't see a voltage drop, this test won't be valuable.

 

[alflash]

I assume that there is no need to reduce it below 2kOhm, since we do not know the permissible load capability of the PMC ECU output.

Excuse me, but I do not understand the question. I base it on the fact that with all these checks of heater control from the generator and when checking control from the PMC ECU with an external resistor between the RMI and PWR contacts, the heater is powered through the PWR contact.
https://alflash.com.ua/2019/to_rav4ev/cab_heat_w2.png
Please describe the question in other words.

 

[Rakesh Suresh]

My earlier question was if we should connect the pwr to positive terminal to rule out the possibility that ecu isn't able to supply enough current to pwr, but given pwr doesn't see a voltage drop, this test won't be valuable.

Sorry, please ignore this question. I got the answer.

Please describe the question in other words.

Should we go even lower on the resistance in the next test?

Should we try with a resistance lower than 2Kohm? May be 1Kohm? Or should I try using a potentiometer and gradually lower the external resistance till the the peak of pwm increases?

 

[alflash]

I think that reducing to 1 kOhm is useless.
But it's up to you to decide.

 

[Rakesh Suresh]

@alflash @asavage Yay ! I got the heater to heat up when I lowered the external resistance to around 333ohm ! I dont know if it is safe though. I measured current draw going through the resistor and draw was fluctuating between 10mA and 30mA.

@alflash Do you know if the heater control signal appear even if D15 is disconnected, in a normally functioning heater?

 

[asavage]

Please clarify: you have the D15 heater connector connected, and have piggybacked a 330 ohm resistor across RMI & PWR? (effectively a pullup resistor) And now your heater responds?

I see you're running the heater tests with its cover off. Is there any chance that there's a magnet on the lid of the heater that activates a reed switch as a safety mechanism? Tesla has that kind of safety on the OBC, but this is a Denso unit and I've never had the cover off of one.

 

[Rakesh Suresh]

Please clarify: you have the D15 heater connector connected, and have piggybacked a 330 ohm resistor across RMI & PWR? (effectively a pullup resistor) And now your heater responds?

That's correct.

I see you're running the heater tests with its cover off. Is there any chance that there's a magnet on the lid of the heater that activates a reed switch as a safety mechanism? Tesla has that kind of safety on the OBC, but this is a Denso unit and I've never had the cover off of one.

The cover doesn't hold itself in place and I haven't noticed any kind of magnet. I will double check tomorrow.

 

[alflash]

@alflash @asavage Yay ! I got the heater to heat up when I lowered the external resistance to around 333ohm ! I dont know if it is safe though. I measured current draw going through the resistor and draw was fluctuating between 10mA and 30mA.

1. Please note the notes. As I assume, max. allowed power for the used R type =0.125W.

2. I hardly understand why the heater "obeys" the pulses of the generator with Rloads > 1.5kOhm (especially when it has a "colleague" inside the LIN transceiver Rnorm.mode).
3. At a current of 0.03A, the power released on a 330 Ohm resistor is P=0.3W.
4. If the pulse amplitude decreases to 7V w and/or w/o connecting D15 to the heater, then this is evidence of an abnormal overload of the PMC ECU unit.
5. Q. What is the reason for the sharp/abrupt change in the duty cycle of control pulses (in the video, at 2nd sec)?
Connecting the D15 connector?

@alflash Do you know if the heater control signal appear even if D15 is disconnected, in a normally functioning heater?

Unfortunately, I do not know the answer to this question.

I will try to repeat the "tabletop" test of the transceiver's response to different Rloads values and different frequencies, amplitudes and duty cycles of control pulses.

 

[Rakesh Suresh]

What is the reason for the sharp/abrupt change in the duty cycle of control pulses (in the video, at 2nd sec)?
Connecting the D15 connector?

This time I did the entire test with d15 connected.

I set the temp at 65 and the ambient temp was about 20 degrees lower. It started off with low duty cycle and increased within a few seconds as it likely determined that maximum heat was needed.

If the pulse amplitude decreases to 7V w and/or w/o connecting D15 to the heater, then this is evidence of an abnormal overload of the PMC ECU unit.

The voltage drop occurs only when d15 is connected

 

[Rakesh Suresh]

I will try to repeat the "tabletop" test of the transceiver's response to different Rloads values and different frequencies, amplitudes and duty cycles of control pulses.

Could you elaborate how to do this test?

 

[asavage]

Oof. I'm confused. If I'm following along correctly:

• The PMC ECU sinks current, as evidenced by (with D15 disconnected)
  • No voltage on RMI
  • PWM-like spikes when a pullup resistor supplies current to RMI

• The heater PCB is not sourcing current (perhaps it should be, as Vlad guessed here)
• In testing, the NE55 supplies current to the heater PCB, as well as not supplying current during the OFF duty cycle. It does two things: supplies current AND a duty cycle that is somewhat recognizable to the heater's receiver logic.

Given the above . . . perhaps the heater PCB cannot supply current and the pullup resistor(s) being used is patching that, in an unhealthy way -- I would be wary of damage to the PMC ECU, trying to sink too much current when using that small 300 ohm resistor.

---

The waveform doesn't look like LIN to me, as there is no sync field, sync break, ID field, etc. But I have little LIN experience.