2012 Leaf: PDM, OBC, or both?

[NJLeaf27]

I just picked up a cheap 2012 Nissan Leaf to tinker with. When I decode the VIN it says SL, but it has cloth seats so I'm assuming it's an SV.

It's clean, with 50K miles, drives fine, but it won't charge on level 1, 2 or 3.

I put a new 12V battery in it right after picking it up, since he needed to use a jump box to get it started so I could drive it up on the trailer.

I was told it charged on level 3, and since the GOM says it only had 6 miles of range, I trailered it around to try on ChargePoint, ABB, EVgo, and older EA Signet on CHADeMO. No luck with any of them. I could at least hear the switchgear going on the EA Signet charger, but no audible clicks from PDM and no lights on the dash.

A few days later, after resetting the codes with LeafSpy, all I was left with was P3173 for the OBC, and some key fob code.

On the J-1772 port, I have the expected 4.3V on the proximity port, but on the pilot I get around 2M ohms on forward bias, and no reading on reverse bias.

When using a level 2 EVSE (from my e-tron), I hear 3 beeps from the car, a couple of clicks from the PDM, the first light on the dash blinks twice, and then I get a fault on the EVSE.

After attempting to level 2 charge, I'm also getting the following codes in addition to the P3173 (some repeated several times in LeafSpy):
B2850-24 (OBC Temp Sen VC-72)
B2840-96 (OBC VC-74)
P31C2-00 (TCE EVC-273)
B2582-00 (HVAC Intake Sensor HAC-69)

According to LeafSpy, my PDM is 3NA0A, OBC is 3NA7A. and the ECM is 3NA1E.

I should also mention the 12V drains down fast. Before doing any of this, I put a brand new battery in it, and two days later in 20-30 degree weather, it was down to 4V, so I left the charger on it overnight, and now I have a Battery Tender on it.

I'm guessing it needs both a PDM and OBC, but I was thinking of trying the PDM first, see if it will level 3 charge, and then make a decision on the OBC.

Any suggestions would be greatly appreciated before I start throwing money at it.

 

[nlspace]

but on the pilot I get around 2M ohms on forward bias, and no reading on reverse bias.

That seems good, indicates that the diode in the forward path is okay.

A 2012 doesn't have a PDM. The OBC is behind the rear seat. The DCDC converter is in the HVJB which is between the Motor/Inverter and the firewall. Without a good strong 12V supply there can be issues with all the relays, contactors and low-voltage power supplies used in all the ECUs.

The failure to charge on level 2 sounds like a failed component in the AC Input section of the OBC, typically the AC X2 safety capacitors or the fuse in the Ceramic pre-charge resistor.

i would also suggest that a weak 12V can cause a multitude of DTCs. A lead acid battery must be kept fully charged at all times or will be permanently damaged by sulfation of the plates.

 

[rsbrax]

Your 2012 Leaf could be the SL variant. The 2012 Leaf SL did not have factory option for leather seats. When I purchased my new 2012 Leaf SL, the dealer agreed to have the upholstery upgraded to leather by a local company for a reasonable price.

 

[FrancoVecchi]

your 12V battery is keep charged while the car is on? MAybe a problem on DC/DC?

 

[cornbinder89]

Just me, sitting in my armchair, but if it were in my garage, I'd attack the 1st DTC, for OBC temp. It may be keeping the OBC from functioning, then see if it will charge.
I'd do that before digging deeper into the charger.
In theory it might be as simple as a bad coolant pump or an air bubble/not enough coolant in the charger.
Once the traction and 12 volt are able to charge, then I would continue down the list.
the draw may be it trying to cool an already cool OBC.
1st see what the charger temp sensor ohms out at cold.

 

[cornbinder89]

not sure if this works? Should be the page from the 2012 manual for the temp sensor in the charger

 

[NJLeaf27]

Thanks for the suggestions and diagrams.

I never thought to check the coolant. That would be crazy if that's what's draining the battery.

I was thinking it could also be the TCU. I stumbled across some old Nissan service campaign for reprogramming it in case the battery is draining.

And I can't believe I thought my Leaf had a PDU. I didn't realize those were only from 2013 on, and that the charger was moved from the rear of the car into the PDU. It's funny too because those go for $300-400, while the older OBCs like I have go for $600-1000.

I was tied up this weekend so I didn't have a chance to work on it. It's cold here now as well, so I'm trying to clear out some space for it in my garage.

 

[cornbinder89]

We'll be intrested in what you find, so post back when you are working on it.

 

[cornbinder89]

In case you don't know, you can download the complete manual for the 2012 here:
https://www.nicoclub.com/nissan-service-manuals

 

[NJLeaf27]

Thanks for the links to the manuals.

I finally cleaned out my garage so I could get the Leaf inside and start working on it.

I think someone was tinkering with this before I got it, because I noticed there's a code for TCU CAN Comm Circuit, so I'm going to assume the TCU was already disconnected to try and fix the 12V drain. I put a Battery Tender on it and it was still down to 5V the following day, so for now I'm just keeping the 12V disconnected.

On a couple of other threads, I saw folks suggesting a bad 12V battery could kill the OBC. If that's the case, I'm going to have to be careful to have the 12V battery topped up before I charge until I can find the source of the drain.

I have to solve the level 2 charging problem first since phantom drain took me from 1.9kWh down to 1.3kWh in a month, so I'm only about 1kWh away from not being able to drive it at all. Is 600Wh a lot to lose in a month just sitting out in the cold?

I pulled apart enough to look at both sides of the charger, and I'm pretty sure it's the original factory part. I just wanted to make sure they didn't already try replacing the OBC.

I'm thinking I should go ahead and replace the OBC first, then see if I can locate the source of the 12V drain, but after going through the manual, the DC/DC junction box seems like a likely culprit, and I assume that's probably the cause of why I can't level 3 charge as well, but I'll do that last.

And I don't think the coolant pump is running constantly because I don't hear anything by where the pump is. The left fender well area is there that pump is right?

Any reputable used parts places you guys can recommend? I'm afraid to order on OBC off eBay because they might just send me another broken one.

I also see one guy selling the entire assembly with capacitor assembly. Is there any chance I could have a bad capacitor in that assembly that could cause the level 3 charging issue or 12V drain?

 

[NJLeaf27]

Well, different behavior today......

I had disconnected the HV service disconnect plug to get at the OBC, and I decided for the heck of it to reset all the codes and try charging one more time.

Now, on level 1 and level 2, the charge light blinks about 7 times before stopping, and I'm only getting two codes. I reset all codes before trying each of the two EVSEs I have, and got the same codes both times. I also hear some humming under the hood by the passenger side that I didn't hear before, but only for 4-5 seconds so hard to pinpoint. I was expecting to hear it from the driver's side since it looks like that is where the OBC coolant pump is in the manual.

B2840-01 6C CHARGER On Board Charger VC-74
P3173-00 C0 EV/HEV On Board Charger Sys EVC-236

 

[cornbinder89]

Something tickles the back of my mind that there are two coolant pumps?

 

[nlspace]

Are you by chance using any extension cords for charging?

B2840-01


Did you happen to open the lid of the OBC and inspect the lower power board underneath the control board for signs of thermal distress, blown/leaking capacitor, cracked ceramic resistors, etc? Take some pictures with good lighting and resolution and post up here.

 

[cornbinder89]

once again points to overheat in the OBC

 

[NJLeaf27]

Yes, according to the manual, water pump 1 is right next to the inverter, and water pump 2 is inside the left fender well and is for the OBC, so I expected to hear that one when I started charging. Maybe the one by the inverter goes all the time while charging, and the one for the OBC only turns on when the OBC tells it to?

I'm just glad to hear something. Before I was only hearing a few beeps, and the first charge light would only blink twice. Now it seems like it's actually charging for 5 seconds.

 

[NJLeaf27]

No extension cord, but it's not the factory Nissan level 1. I see a GM sticker on the back. The level 2 I tried is my Audi EVSE, set to 20A.

But now I'm not getting the OBC overheat code that I was getting before.

Can I take the lid off while it's still in the car, or will I get coolant all over the place? In the videos I've seen replacing the OBC, they always drain it first, but it doesn't seem like all that much fluid comes out.

 

[cornbinder89]

The two codes you have now are OBC related, the 1st is the OBC code and the 2nd is the EVC acknowledging it has received a OBC code.

If you had to get it working tomorrow, I would throw an new OBC on it.
However, that is going at it with a machete not a scalpel.
OBC for the 1st 2 years are not plentiful, and I believe yours is fixable if you can narrow it down and have the time.
Since day one, you have had DTC's that say there is an overheat detected in the OBC.
That is where I would focus. esp if you can find where the temp sensor is at, and make sure it is in range for the temp it has at present.

 

[cornbinder89]

https://imgur.com/gallery/2012-nissan-leaf-obc-repair-B9Z2cWD
shows the early charger opened up, don't know if that will help any.

 

[nlspace]

The lid can easily be removed (but it does require a security Torx bit for one screw) and there is no issue with coolant. The coolant flows in a heatsink on the backside of the OBC. You can try charging with the lid off also, as long as you are careful not to touch anything inside while doing so. Just listen for clicking or buzzing sounds.

When you try to charge take notice of the sounds and sequence as it tries to start the charge session, e.g. relays and contactors in the traction pack will clack, then the EVSE relay will click to supply AC to the car, then the AC relay inside the OBC will click to start the session. If there is an issue in the AC Input section of the OBC (a very common failure mode), then the session will time-out after 5 seconds or so. There are numerous pictures of internal parts with damage, not sure how to search to find those.

This ceramic resistor with the green markings has an internal thermal fuse. All 3 resistors are in the precharge leg of the AC input and the session will not start until it detects AC thru that path. You can check if they are okay using the resistance check function of your DVM and measure about 15 Ohms between the Neutral leg and the "N" solder joints found in the upper left side of the column of double solder junctions.

 

[cornbinder89]

If you go to the link in my post #6, it says there are three temp sensors on the OBC boards, but not exactly where on the board