DIODE FIXED!

[coulomb]

- Pilot:
Resistance: 4 MOhm (+ on Earth), no resistance (- on earth)
Diode Test: no connection (+ on earth), 1.77V (- on earth)

Those readings seem normal, although I don't know why you get "no resistance" with positive on the control pilot pin (negative on earth).

Since, stated before, resistance of the pilot-ground should be low in one direction, but is not.

? "No resistance" is "low in one direction", is it not?

I think that this is yet another case of "it's not the diode". So something not quite as simple.

Is it possible to make a measurement of the pre-charge resistors, equivalent to the below for the iMiEV? It will not be 9.4 ohm for the Leaf, since it has 3 resistors to the iMiEV's 2, but open circuit pre-charge resistors are a common failure mode with the iMiEV OBCs.

The 1/2 ohm measurement is when the relay is energised; ignore that for now.

 

[winfried]

Thanks for the hint.

- Pilot:
Resistance: 4 MOhm (+ on Earth), no resistance (- on earth)
Diode Test: no connection (+ on earth), 1.77V (- on earth)

Those readings seem normal, although I don't know why you get "no resistance" with positive on the control pilot pin (negative on earth).

Since, stated before, resistance of the pilot-ground should be low in one direction, but is not.

? "No resistance" is "low in one direction", is it not?

Yes, one direction 4MOhm and the other no connection "0L", when I do the diode test mode, I see 1.77V in one direction, "0L" no connection in the other. The diode D547 on the board measure in diode test "0.7V" and "0L" and as resistance 4MOhm even they are two and I am not sure the same type, maybe a fast in parallel.

Is it possible to make a measurement of the pre-charge resistors, equivalent to the below for the iMiEV? It will not be 9.4 ohm for the Leaf, since it has 3 resistors to the iMiEV's 2, but open circuit pre-charge resistors are a common failure mode with the iMiEV OBCs.

The 1/2 ohm measurement is when the relay is energised; ignore that for now.

Thanks, I will measure resistors in the next days and report back.

 

[coulomb]

Yes, one direction 4MOhm and the other no connection "0L",

Oh. OL is "no conduction", not "no resistance"; no resistance is zero ohms.

The resistance measurements aren't terribly meaningful in this circuit, as the voltage will be too low to turn on the diode. 4M ohm in the reverse direction indicates a bit of leakage, but that would not be significant here. [ Edit: Although IF the diode was shorted, then the resistance measurements should make that obvious, as you'd basically see the 2.74k resistor both ways. ]

when I do the diode test mode, I see 1.77V in one direction, "0L" no connection in the other. The diode D547 on the board measure in diode test "0.7V" and "0L"

Again, both of these are normal.

and as resistance 4MOhm even they are two and I am not sure the same type, maybe a fast in parallel.

I'm not convinced that the two diodes are in parallel. It looks like the cathodes are commoned, but I think that the anode of D552 goes somewhere else. Though I can't think what it's doing.

 

[MrJodie]

...
- Pilot:
Resistance: 4 MOhm (+ on Earth), no resistance (- on earth)
Diode Test: no connection (+ on earth), 1.77V (- on earth)
...

Winfried, same for me.

I lost charger yesterday.

4.3V and 4.5MOhm

I am sorry for you, what I did until so far:

- removed seats and covers to access the charger-
- I turned off high Voltage (-12V + Plug), wait for 10 Minutes
- Opened the OBC and inspected: optical everything seems to be ok (no broken condensers...)
- screw out the control board PA4063RP120 to inspect the diode in there:

The famous D547 seems to be doubled on my board and I measured, 0.64V and 0L, so it seems to be fine.
Also, other diodes near seams to behave normal (0,54-0,7V) in one direction in the other sometimes1.7V, but these could be external parts.

Anybody know where the resistors responsible for measurement of the low resistance on the board are seated ?

So I will assemble everything again, so I can Chademo charge.

PS.: Seems I have to order a used one somewhere, if I find one.

I have started to investigate Yahoo Japan for a OBC.

 

[Pashko90]

Winfried, same for me.

I lost charger yesterday.

4.3V and 4.5MOhm

I am sorry for you, what I did until so far:

- removed seats and covers to access the charger-
- I turned off high Voltage (-12V + Plug), wait for 10 Minutes
- Opened the OBC and inspected: optical everything seems to be ok (no broken condensers...)
- screw out the control board PA4063RP120 to inspect the diode in there:

The famous D547 seems to be doubled on my board and I measured, 0.64V and 0L, so it seems to be fine.
Also, other diodes near seams to behave normal (0,54-0,7V) in one direction in the other sometimes1.7V, but these could be external parts.

Anybody know where the resistors responsible for measurement of the low resistance on the board are seated ?

So I will assemble everything again, so I can Chademo charge.

PS.: Seems I have to order a used one somewhere, if I find one.

I have started to investigate Yahoo Japan for a OBC.

Where are you located at? If somewhere in 500 miles radius from Los Angeles, I have few chargers for exchange. Shoot me a text at 5624999091

 

[MrJodie]

I have started to investigate Yahoo Japan for a OBC.

Where are you located at? If somewhere in 500 miles radius from Los Angeles, I have few chargers for exchange. Shoot me a text at 5624999091

I am in Australia

 

[SouthOzLeaf]

After many months of not being able to charge the Leaf, I followed the steps and installed a diode behind the plug. The car is charging!

Here is hoping that it will continue to work.

Thank you for your guidance.

 

[LanguidSphinx]

Does this infamous diode issue only apply to earlier models? Searching shows lots of 2011-2013 models talking about this.

I wonder if the circuit changed - I have a 2018 and I measure 1.5MegOhms or so with the meter GND probe on the socket GND, and open circuit the other way around.

I have no charging issues right now, across multiple public and private EVSE. It's possible all chargers I have tried so far don't do that check, but seems unlikely, so do we know if the car charger side changed? Maybe it's only the model years where the charger was behind the seats that can have the diode issue? This is all for curiosity/learning, again - no problem right now.

 

[coulomb]

wonder if the circuit changed - I have a 2018 and I measure 1.5MegOhms or so with the meter GND probe on the socket GND, and open circuit the other way around.

Multimeter resistance ranges are designed to work with voltages so low that silicon junctions (like diodes) barely conduct at all, hence the megohms reading.

Even on the diode range, you will get the 2.7 kΩ resistor in series, and with the typically 1 mA test current, you will likely see over 3.0 V in the forward direction, and no conductivity (typically indicated by OL for OverLoad) in the other direction. So your diode is probably OK, though a test on the diode range would be more indicative.

do we know if the car charger side changed?

Certainly, since the On Board Charger is 6.6 kW versus 3.3 kW on the earliest models. But the control pilot has to look like a diode in series with 2.7 kΩ to protective earth, since that's the J1772 specification. So very likely that critical part of the circuit hasn't changed at all. It's a pity; for a penny or two more, they could have put a larger, more robust diode in that position, eliminating a moderately common failure that typically costs thousands of dollars to fix. Alas, when the diode fails it often fails open circuit, meaning that the diode hack would not work, and the car won't charge at all.

 

[moapys]

After many months of not being able to charge the Leaf, I followed the steps and installed a diode behind the plug. The car is charging!

Here is hoping that it will continue to work.

Thank you for your guidance.

Glad to see that works: mine has not yet begun to act up, but I want to have done my research in advance… Is there a post or thread that was the most informative while chasing down that diode hack? Much obliged!

 

[Burt]

What I’m seeing is the 1N4003 is only rated for 200v. Shouldn’t we use the 1n4007 good for 1000v?

 

[nlspace]

What I’m seeing is the 1N4003 is only rated for 200v. Shouldn’t we use the 1n4007 good for 1000v?

For a 12V circuit? A bit overkill but either would work and they are cheap and plentiful.

@coulomb said:

I'm not convinced that the two diodes are in parallel. It looks like the cathodes are commoned, but I think that the anode of D552 goes somewhere else. Though I can't think what it's doing.

i can confirm thru inspection that those 2 diodes are in parallel.

 

[Burt]

For a 12V circuit?

Thanks. You can tell by my question, I’m a know nothing. Is this something that is progressive such at some point I won’t be able to charge on 110v? Or can I muddle along indefinitely with L1? Do I need to address this in the near term?

 

[cornbinder89]

Thanks. You can tell by my question, I’m a know nothing. Is this something that is progressive such at some point I won’t be able to charge on 110v? Or can I muddle along indefinitely with L1? Do I need to address this in the near term?

It is part of the circuit that controls the OBC, if it fails, the input voltage is a moot point, the OBC will not function. Either it works or it doesn't, there is not middle ground.