Charging stopped due to system malfunction

[alflash]

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.

I assume that the ATA6624C LIN transceiver is used only as an input buffer for the PWM signal of the heater control.
This version is confirmed by the video oscillograms of the control voltage and the fact that a copy of the input signal with an amplitude of 5V is constantly present at its RXD output (attach.).

At the same time, the TXD input has a constantly high signal level.

 

[alflash]

Could you elaborate how to do this test?

There is no need to repeat this test. Power was connected to the low-voltage part of the heater.
1. The oscilloscope is connected to the RXD output (pin #9 of ATA6624C ).
Changes in the amplitude of control pulses from 7 to 15 volts and changes in their frequency from tens to hundreds of Hz provided an adequate display of frequency changes with a constant amplitude (approximately 5 V).
2. The change in voltage on the RMI contact was checked when various resistors (56 Ohm, 750 Ohm, 2.1 kOhm) were connected to it and to the GND contact.
In this case, a current of 4.8, 2.36, 1.72 milliamps, respectively, flowed through them.
Let me remind you that this test will not solve the problem of your heater, because I do not understand why it works from the generator with a resistance of 1.5 kOhm between +12V and its output (aka RMI input), but does not work from the PMC ECU with a similar resistance with a nominal value of 2kOhm (but work with 333 Ohm and with a noticeable drop in the amplitude of control pulses).
Unfortunately, I don't know the RMI signal generation circuit in the PMC ECU

 

[asavage]

I just tested my white car's heater for the first time since I purchased it: it's in working condition. I crimped up some test jumpers.

Green = Pwr
White = RMI
Black = Ground

Climate control set to Auto, 75°F (it is quite cool here today, 47°). Car is in "Ready" mode.

With D15 "connected" (via jumpers), the system is generating heat, the coolant pump is running.
Pwr = 14.6v


I moved the voltmeter probe to RMI, it shows the PWM average.




I then disconnected RMI. The Cabin Heater is directing ~13.5v to the PMC ECU via RMI.



Rakesh: in similar circumstances, does your heater supply ~13.5v toward RMI, when only RMI is interrupted as above (ie Pwr & Gnd are connected via the D15 harness)?

 

[Rakesh Suresh]

Rakesh: in similar circumstances, does your heater supply ~13.5v toward RMI, when only RMI is interrupted as above (ie Pwr & Gnd are connected via the D15 harness)?

Coincidentally, I tested this today. It does not. However, I did it directly on the pcb using my replacement connector which should be equivalent.

Additionally, if RMI is connected to PWR via a resistance
1. Rmi Open - 400 mV, mostly noise
2. 10k resistor - still very low voltage
3. 368 ohm - 5.2v at RMI.

The voltages here are very close to peak voltages I see with d15 connected via external resistance.

White crocodile clip is RMI. In the video below, I connect and disconnect rmi to pwr via 368ohm resistor.

https://1drv.ms/v/s!AoMSicNQxi7y5y9hFlwArAT_fYnP

And there is no magnet on the heater lid.

 

[asavage]

Coincidentally, I tested this today. It does not. However, I did it directly on the pcb using my replacement connector which should be equivalent.

1. Rmi Open - 400 mV, mostly noise

I would call this a failure on the heater PCB. You're welcome to borrow the heater from my white car to confirm, if you like; I will not be driving it for a while yet.

 

[Rakesh Suresh]

I would call this a failure on the heater PCB

Any guesses what kind of failure it may be? Like a short due to some IC failing or is it due to a resistor that has failed open

If it could be a simple resistor that has failed open, do you think inspecting the resistances using a multimeter any good?

 

[Rakesh Suresh]

You're welcome to borrow the heater from my white car to confirm, if you like; I will not be driving it for a while yet.

Thanks !

 

[asavage]

It would be nice if a resistor failed open, but I suspect this circuit isn't that simple; look at the ΔV between input 14.6 and output 13.5 . I think there's more going on there than just a pullup resistor. Perhaps Vlad -- who has a lot more experience with this unit -- can suggest a troubleshooting procedure.

Given a working unit to use for known-good test points, it might be able to be tracked down. I no longer do component-level repair like this, except when I'm backed into a corner. If a replacement can be purchased, I generally purchase it, even though I might be able to repair it. You get out of practice, plus my time is more valuable to me doing things I enjoy, and I haven't enjoyed component-level repair on modern electronics for a long time now. Witness how old my $2000 'scope is -- I bought it new!

 

[alflash]

1. The heater "listens"/"obeys" the signals of a worthless chinese generator, whose output signal is connected to +12 via a 1.5 kOhm resistor and a LED,
2. The heater "understands" the control signal from the PMC ECU only when the RMI line is connected to +12V via (IMO. unacceptably low) 333 Ohm resistance.
3. The test described above (connecting RMI to GND via different resistors) confirmed the diagram from the datasheet: RMI is connected to +12V in a more complex way than simply via a constant resistance,

4. In connection with all this and unfortunately, I have run out of versions of the causes of the malfunction and list of possible checking for search and for
troubleshooting has been exhausted.

5. Checking by installing a working heater could make a final verdict on the cause of the malfunction.

Of-topic. Troubleshooting and repairing the board at the component level is usually done due to the hopeless lack of an alternative way to troubleshoot the fault. For example, repairing a BMB to eliminate the cause of intermittent malfunction with tesla BMS_f107 code.

 

[asavage]

For my future self: I put together the two wiring diagrams for this system that Toyota had separate, and parked it in the "All things heater" thread.

 

[alflash]

... White crocodile clip is RMI. In the video below, I connect and disconnect rmi to pwr via 368ohm resistor.

https://1drv.ms/v/s!AoMSicNQxi7y5y9hFlwArAT_fYnP ...

In this "episode"/"scene" was the heater active?
In other words, were there "traces" of the control signal on the RMI line similar to those shown earlier?

 

[alflash]

Witness how old my $2000 'scope is -- I bought it new!

Off-topic. This ancient friend of mine is almost 50 years old

My (6 ch.) USB oscilloscope is also almost 20 years old

 

[Rakesh Suresh]

In this "episode"/"scene" was the heater active?
In other words, were there "traces" of the control signal on the RMI line similar to those shown earlier?

The car was not even turned on in this test. D15 was disconnected.

 

[alflash]

The car was not even turned on in this test. D15 was disconnected.

I stop understanding you...
Please explain to me.
If "...the car wasn't even turned on in this. D15 was disconnected.", then
1. Where does the supply voltage on the connector come from?
Is IGCT 3 relay active/closed in this situation/state?

2. Was the resistors connect between RMI and PWR?

3. What's the point of overloading the PMC ECU RMI output when it's known that when connected to 12V through a 10 kOhm resistance, there are adequate control pulses on it? And with its resistance of 333 Ohm and D15 connected, these pulses are there, although with a reduced amplitude.

 

[Rakesh Suresh]

If "...the car wasn't even turned on in this. D15 was disconnected.", then
1. Where does the supply voltage on the connector come from?
Is IGCT 3 relay active/closed in this situation/state?

The point of this test was to confirm my hypothesis that some kind of failure on pcb was pulling the rmi voltage down. The results did confirm the discrepancy between open voltage at rmi when compared to asavage's working heater

PWR is fed from the crocodile clip connected to the positive 12v battery terminal.

I am not sure about the IGCT3 relay.

Was the resistors connect between RMI and PWR?

Yes, refer to tests 2, 3. In this test, I am referring to RMI as the pin on the pcb that connects to rmi on the D15 connector.

What's the point of overloading the PMC ECU RMI output when it's known that when connected to 12V through a 10 kOhm resistance, there are adequate control pulses on it? And with its resistance of 333 Ohm and D15 connected, these pulses are there, although with a reduced amplitude.

I think you misunderstood. The ECU is not even in the picture. This test is only feeding pwr to the heater pcb, and checking rmi voltage under different conditions like being open

These are 3 pins used in this test and referring to them as GND, RMI, PWR.

 

[alflash]

PWR is fed from the crocodile clip connected to the positive 12v battery terminal.

1. Sorry for being frank, but such a check is not entirely correct, since it may not be enough to connect 12 V power supply to activate the PMC ECU. I do not exclude that its output stages use not only resistors, but also controlled semiconductor current sources when switching on/activating the cabin heating (on command from the Air Conditioning Amplifier Assembly).
2. Note: As I understand, respected savage described checks in READY mode.

...I think you misunderstood. The ECU is not even in the picture. This test is only feeding pwr to the heater pcb, and checking rmi voltage under different conditions like being open...

3. The results of a similar test when connecting RMI to PWR with different resistances I described earlier (item 2 in https://www.myrav4ev.com/threads/charging-stopped-due-to-system-malfunction.2692/page-11#post-32237).

 

[Rakesh Suresh]

Sorry for being frank, but such a check is not entirely correct, since it may not be enough to connect 12 V power supply to activate the PMC ECU.

I repeat, ECU is disconnected from the pcb and test is performed on the heater pcb. 12v is connected to pwr on the pcb

 

[Rakesh Suresh]

Note: As I understand, respected savage described checks in READY mode.

The difference between mine and @asavage 's tests would be the absence/presence of High voltage supplied to PCB. Given that we are only testing the low voltage components on the PCB, do you think if that matters?

 

[asavage]

I repeat, ECU is disconnected from the pcb and test is performed on the heater pcb. 12v is connected to pwr on the pcb

This would be as if you were testing the heater out of the vehicle, disconnected from the PMC ECU.

I was hoping you'd duplicate my test setup so the results could be compared. I can't describe how many times I thought that bypassing some harness -- thinking "this connects to the same place" got me into trouble.

I had the white car in Ready mode, I installed three harness jumpers for the D15 external connector, and jumpered Pwr & Gnd. The white RMI jumper I cut, so I could measure both sides of D15 (the PMC ECU side; the heater side) but I could also connect them and measure again -- and run the heater, in my case.

You have changed the test conditions, and I understand why, but you can't be certain that something isn't different. I know what the documentation says, and I can make educated guesses, but the results of different test points has led to incorrect results (for me) several times.

 

[asavage]

The difference between mine and @asavage 's tests would be the absence/presence of High voltage supplied to PCB. Given that we are only testing the low voltage components on the PCB, do you think if that matters?

Yes. It absolutely could matter. I have no idea of the interaction of the heater's LV circuitry with the HV; for all I know, the LV side goes into a limp mode or shutdown (or doesn't respond) if the HV side isn't ready for operation.