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@alflash @asavage I was able to replace the Rav4 heater pcb (bottom) with a used Ford focus ev heater (top) which cost around $300, without any changes. I saw the heater control pwm and a peak current of 15A. Temp increased far too quickly to make a video of it I clamped the heater and filled...

What I meant was that all these Denso heaters carry a risk of blown IGBT, in addition to the unique way my heater has failed. Are you referring to this? https://www.myrav4ev.com/threads/all-posts-heater-failed-service-bulletin-tsb-0111-14.823/post-30506 I am a bit confused. My broken heater...

https://ev-olution.yolasite.com/Nissan-Leaf-Heater-Fault.php I was under the impression that all these denso heaters share the same mode of failure. And looking at the nissan pcb pics on the above link, I would bet that it fits directly 😀

I agree with that as a general rule of thumb to make decisions, but it is a bit complex in this particular case because of the following. @asavage Please correct me if I am mistaken in any of the points. The heaters themselves have persistent issues. Even a new one doesn't appear to provide the...

Yes, I have been doing this. Using some overly simplistic (and possibly ridiculous) assumptions, drew a circuit of the heater and solved the equations. (The open circuit Resistance between RMI and gnd is 3.3 megaohm, so this diagram is true only when voltage is applied) What is the resistance...

@alflash I tested again with the exact same setup as @asavage , voltage at RMI is close to zero. Channel 2 is rmi and ch1 is disconnected. Also checked the current passing thru ground. The numbers read from clamp meter 0.22A and using a regular multimeter 0.05A are vastly different. Not sure...

Is the behavior same when heater is turned off?

@asavage I am curious about how a good heater will behave in these two scenarios. 1. Does ecu provide pwm on rmi when it is open and d15 disconnected 2. When cabin heat is not requested, what's the voltage at rmi with d15 connected. Voltage at rmi is close to zero in all scenarios unless I use...

I agree that there is a possibility but in most of my tests one of the probe is connected to pwr and I have never seen pwr being cycled at any point by the ECU. Yes, I will repeat the test using the same method.

The setup for this test is very similar to the NE555 pwm test that got the heater working, but voltage at rmi is tested under 3 conditions. The idea was not to activate the heater, but just to see the behavior at rmi pin. I did 3 tests, open rmi and two more tests connecting through 2...

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?

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

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...

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

Thanks !

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?

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 -...

Could you elaborate how to do this test?

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. The voltage drop occurs only when d15 is connected

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