DIODE FIXED!

I am happy HAPPY HAPPY!!! to report that my car now charges successfully at all charging stations. Background: there are several threads on this forum about Level-2 charging failing at certain stations but not others; the fix is to replace a diode and not to have Nissan charge you $2800 to replace the entire charging module.

I realize this is yet another thread on the same topic, but I thought I'd share some info about the fix and hopefully make it easier on other people. I used these steps as a starting point: https://darelldd.smugmug.com/Automotive/Electric-Vehicle/n-7QXrQ/Nissan-Leaf-charging/i-rcsHp8p

Here's my take on these steps, slide by slide. I've added BOLD to the actual steps where you do something. The whole process is five steps, really.

1. I bought 25 of these diodes at Amazon for $6.00. Seemed like the easiest way to get the right thing.
2. This image means nothing for repairing your Leaf. Skip it.
3. So you know what's broken.
4. This step is easy enough. A flat-head screwdriver helps. Or strong fingernails.
5. This was the hardest part for me. (Still not that hard.) I had trouble finding the little clip on the bottom to press so I could pull it out.
6. Nothing to do here.
7. Removing the overflow tank was completely unnecessary for me...
8. ... because I had no need to release this connector.
9. This step is also unnecessary.
10. Just unscrew these four screws to get to the wire. Since I hadn't removed the connector, mine didn't come this far out. Not an issue; you don't need to pull it out this far just to do the soldering.
11. Find the right wire.
12. That's the one.
13. Put that diode where it belongs

That's it! Step 1 is buy the thing, step 4 is remove the cover, step 5 is disconnecting the orange connector, step 10 is unscrewing so you can pull out the unit to get to the wire. Step 13 is adding the diode.

And voila, it works. (Step 14, put it all back together.)

Thank you all for your help. So glad to have this issue behind me without costing three grand to do it.

Congrats!

Awesome! I sure hope not too many other people pay thousands to get their OBC replaced or dump their Leaf w/a failed diode.

That is great, thanks for the confirmation that it works. It is concerning that if that fails, it is half the value of the car potentially. This fix (if diode is issue) really takes the sting out of it.

I hope to never have to do this, but it's awesome to have such a simple fix explained so clearly! I'm saving this as a PDF in case that slide deck ever disappears from the web...

Here's the URL, in case anyone wants it:

https://1drv.ms/b/s!AjONM_UrXWS8-xqfBWuDqcPAFCuK

Congrats on the DIY fix. These kinds of things are great examples of where Nissan should publish a an official way to fix it of replacing some expensive part, but also detail exactly what has failed so enterprising individuals can go about repair this way.

Very happy for you...and thanks for sharing your success with the forum!

What does the connector in photo #9 energize ?

SageBrush said:

What does the connector in photo #9 energize ?

Click to expand...

I truly have no idea. It didn't seem required for this fix.

Lets look at the protocol:

https://en.wikipedia.org/wiki/SAE_J1772

That wire is the Control Pilot wire. The EVSE sends the information on the available current with a square wave. The "speed" of the wave is the power available. The diode does not have any effect on that.

A 1 kHz square wave at ±12 volts generated by the electric vehicle supply equipment (EVSE; i.e., the charging station) on the control pilot to detect the presence of the vehicle, communicate the maximum allowable charging current, and control charging

Click to expand...

Now the diode has 2 effects:
1. Current flowing from the car back to the EVSE is stopped.
2. There is a voltage drop of 0.7v from the EVSE to the car on the square wave. It keeps the same speed but the peak to peak voltage is lower.


According to here (guy building his own EVSE for 30$): http://www.instructables.com/id/Arduino-EV-J1772-Charging-Station/

The EVSE sets the duty cycle and the EV adds resistance from the pilot the Ground to vary the voltage. The EVSE reads the voltage and changes state accordingly.

State Pilot Voltage EV Resistance Description
State A 12 N/A Not Connected
State B 9 2.74k Connected
State C 6 882 Charging
State D 3 246 Ventilation Required
State E 0 N/A No power
State F -12 N/A EVSE Error

Click to expand...

So the car "consumes" some part of the 12v by applying a resistor. The value of the resistor thus the voltage determines the state. Remember you`re lowering the voltage 0.7v that what the spec says.

It seems like there should be no effect because the pilot voltages steps are much bigger than the 0.7V. Maybe it does this because the 12v is not calibrated on the EVSE side or the resistors don`t have a good enough tolerance.

By applying a voltmeter (or better a spectrum analyser) on that wire while charging you could see exactly where the problem is and how to properly fix it.

If the diode does the trick, it`s probably a tolerance issue on your car or the EVSE or both and lowering the voltage brings you back on track.... anyway I don`t think (disclaimer if you car burns I`m not responsible) there is anything bad that could happen.

Parc2407 said:

...
If the diode does the trick, it`s probably a tolerance issue on your car or the EVSE or both and lowering the voltage brings you back on track.... anyway I don`t think (disclaimer if you car burns I`m not responsible) there is anything bad that could happen.

Click to expand...

No, that's not why. The pilot signal swings from -12v to 12v. The addition of the diode keeps the resistors in the car from affecting the negative voltage swing. EVSEs that do the "diode check" look for a pilot that does go all the way to -12v when the positive half of the signal is pulled down as verification that an EV is pulling the signal down instead of the voltage drop is being caused by something like the plug sitting in a puddle. WIthout the diode check, an EVSE might falsely interpret that kind of short as the signal to turn on the AC pins. EVSEs that don't do the check just assume that their GFI circuits are sufficient protection.

Did you disconnect main battery before removing the charging port off the car?
I need to clean the charging port in a Nissan Leaf 2014.

I disconnected the traction battery fuse located on the floor between the front and back seats, before removing the inlet and wiring.

This may not be necessary but it provides an extra level of safety.

Tried this lastnight, it dodn't fix my faulty OBC issue. Will have to take it in to the dealer to get a quote.

2012 Leaf with 70k miles. On second battery.

Anybody in Lower Mainland BC have a line on an onboard charger?

ChaDeMo side works, but K2 side is hooped.
Doesn't take 110 or 220 charge.

Or if anybody knows a reliable local person who can source a used part and do the repair, without absolutely fucking me up the ass as the dealer attempted to, that's also an option.

I can do it if I can source the part, but it will take 3x the time..

Would prefer to buy locally rather than eBay.

Any help most appreciated.

Have you looked at the information on failed diodes? Usually L-1 charging works with that, IIRC, but I just got up and may be remembering it wrong.

No, not sure what that is.

Does anybody have a link to actual part required?
Fix seems easy enough, but I'm not good with electrical.
So what diode am I buying?

I googled the diode fix
It's very plausible that this is the issue.

Does anybody have a link to part needed?

I'm not electronically inclined, I'm sure there are tons of different diodes of different specs.


In case mechanic is needed, please post your non-dealer recommendations.

Reread the original post - the OP followed someone else's instructions (he provided a link) and in those instructions it mentions diode part # 1N4003 (for which Amazon has several listings).