L2 not charging, L1 ok

[davewill]

Took the car in to the dealer's service department. We managed to duplicate the problem just exactly as Davewill had mentioned above. Charging works on L1 & AV, but fails on Chargepoint & Schneider.

Ding! I know what the problem is! ...

Yawn...that is so yesterday.

[DarkStar]

Yawn...that is so yesterday.

But now he doesn't need to wait for the dealer to figure it out!

[Herm]

The diode in your charger unit is fried. The L1 & AV units don't test for the +/- 12 volt signal, while the ChargePoint, Schneider, and Blink do.

I assume is there for safety in the Leaf, what does it actually do?

[davewill]

I assume is there for safety in the Leaf, what does it actually do?

The car signals to the EVSE to turn on power by placing a specified resistive load on the +12v/-12v pilot signal. It is theoretically possible to get the same load from dropping the handle into a puddle of dirty water. The diode allows the load to only affect the positive side of the signal, and the EVSE is supposed to check for this to be sure that it's really a car that's loading the signal before turning on the high voltage. Some EVSE manufacturers figure that their GFI circuitry is sufficient protection in this admittedly rare happenstance, and don't bother to implement the diode check.

Not having a functional diode in the car doesn't create a safety hazard, but does create the described scenario where the car doesn't work with some EVSEs.

[LTLFTcomposite]

The diode in your charger unit is fried.

What is involved in fixing that? Will they just change out the charger?

[davewill]

The diode in your charger unit is fried.

What is involved in fixing that? Will they just change out the charger?

Yeah, that's what they did for the last guy.

[garygid]

A simple resistance check between the CP (Control Pilot) input pin and the Ground pin on the LEAF's J1772 socket, with the LEAF Off ... should check for the diode:

The resistance should be about 3k ohms in one direction (polarity) and very high resistance (probably over 100k ohms) in the other polarity.

[davewill]

A simple resistance check between the CP (Control Pilot) input pin and the Ground pin on the LEAF's J1772 socket, with the LEAF Off ... should check for the diode:

The resistance should be about 3k ohms in one direction (polarity) and very high resistance (probably over 100k ohms) in the other polarity.

I'm not sure you can count on seeing the diode when the circuit isn't active. I'd use a O-scope to look for -12v on the pilot signal during normal charging.

[pjoseph]

After ~5 days of L1 charging and a further 9 days of just sitting in the garage (road trip in the ICE car), the Leaf is now charging again from our L2 EVSE (Schneider).

Am baffled and intrigued. Had planned to drop it off at the dealer later this week, but will wait now. The dealer technician had mentioned earlier that Nissan is anxious to troubleshoot it. Wondered whether they would replace the $2,000 onboard charger or the $0.50 diode.

So the error is transient, what car makers sometimes call as a soft error. An analogy of a check engine light coming on occasionally in an ancient ICE car.

[garygid]

Probably a $0.04 diode, and less in quantity.