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Leaf - Gen 2 PDM/OBC/charger no output power - L1/L2 charging

7132 Views 119 Replies 4 Participants Last post by  evVanagon
I'm having a problem with L1 charging all of a sudden. This vaguely coincides with the time I put dielectric grease in the J1772 port for the winter and when the temperatures started to drop.

  • 2015 nissan leaf OBC
  • 2013 24kWh battery
  • 0 to -14C temperature outside. Battery temp is always above zero (i have the battery externally heat traced).
  • Resolve EV VCU

- When this first problem started in the fall with temperatures dropping, but with the battery well above zero, I originally plugged the EVSE in overnight and the next day it dropped 40% overnight. Indicating no charge. Then noticed with my smart outlet that there was no current draw from the vehicle. Strange. So i started investigating.

What's happening is the EVSE plugs in, I have verified the light on the EVSE says charging, I have verified the OBC is getting 100V AC inside the OBC. The OBC also registering 100V AC after the black relay before going into the underside of the OBC. So i know the OBC is getting AC voltage from the house. The EVSE does not complain with any fault lights or error messages. I have tested two different EVSEs. One stock Nissan EVSE that i've used since day 1 and my evse. Both show that they start charging but 0 Watts are being drawn from the vehicle's OBC.

  • I check LeafSpy Pro, I am seeing a 1-2A (300-600W) draw from the battery when the car wakes up by the presence of the J1772 plug being connected.
  • I have pulled apart the OBC top and bottom to check from any blown components. Nothing seems out of the ordinary.
  • The OBC is getting 100V through the EVSE properly.
  • Disconnecting the HV battery mains at the EVSE and checking the output of the OBC. I'm getting around 2-4Volts DC. This is strange.
  • I have checked the D400 (or D408?) diode and the D108 diode inside the OBC. Traced it from the control pilot circuit. They seem fine. D400 has ~11Mohms of resistance forward. And 0.542V with the multimeter's diode tester. If I jump diode D400, then the evse will stop charging and report a Diode check error. This helps me eliminate the diode as a symptom.
  • D108 also seems to be fine and reports 0.352V in the forward direction.
  • PP pin to ground is 4.74V DC
  • CP pin to ground is 11.78M Ohms forward
  • With logging EV-CAN messages. I'm seeing 0x679 register when J1772 plugged in. 0x390 - OBC_AC_status voltage is 100V, 0x390 - OBC_Charge_Power report 0kW. I'm seeing 0x390 and OBC_Charge_Status=charging or interrupted. Ox1DB seeing LB_Current with -0.5 to -1A.
  • 12V battery is charged and tested to be good.

Other things I noticed while in there:
Also, in this investigating R8000 and R80008 seem to be shorted. And with a magnifying glass I was able to see "0" printed on the top which makes me beleive these two resistors are just "jumper" resistors in the form of a SMD component.
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There should be no voltage getting to the PFC section until after the black relay gets energized to pass the AC to the bridge rectifier.
Well shouldn't there be rectified DC getting to the PFC for precharging?
  • TP9037 = 171 ohms to GND, 27mV to GND
  • TP9038 = 1.8kOhms to GND
  • Vout 4.8V and not within spec of 10-21V to turn UCC28070 on
  • T1 Vb to GND = 27mV
  • T2 Vb to GND = 0.785V
  • T3 Vb to GND = 0V
  • T4 Vbase and Vemitter are both 5V to GND
In the older versions, the AC voltage is sensed before it gets to the rectifier, and the DC voltage and current that is created from the bleed-thru of the thermal resistors is monitored also. It's all done very quickly and is used to determine if the "black" relay will be energized or not. If there is a fault then the relay is not energized and the EVSE is cut off. Happens very fast, would need a scope to capture it.

The thermal resistors give a path for the inrush current to bypass the contacts in the black relay to reduce arcing damage.
Ahhh, since that happens so fast, i'm probably only measuring values once the system is cut off.
@kennybobby do you know where, or have a best guess at where the temperature sensors are? Have Gen 1 makel/model numbers? I want to rule these out of the equation.
The Gen 1 OBC is made by Nichicon; i haven't been on the mynisslaef site for some time ever since my 2012 was rear-ended and total loss.
Here are some part numbers and --> firmware update numbers:
296A0 3NA0A → 296A0 3NA0E​
296A0 3NA1A → 296A0 3NA1E​
296A0 3NA2A → 296A0 3NA2E​
296A0 3NA3A → 296A0 3NA3E​
296A0 3NA4A → 296A0 3NA4F​
296A0 3NA5A → 296A0 3NA7A​
296A0 3NA6A → 296A0 3NA7A

i found this wiring diagram which shows a temperature line and the interlock lines. i suppose you are bypassing the interlocks to do your testing? i wish the PDM wiring diagrams were better documented.

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Not sure what this component is. It's not a grounding point. There are two other ones near the top-side's top control board's main chip.
- I also checked resistance of different pins of CN9006 against ground when this board was cold, and at room, temperature and found 5, 9 to be very sensitive to temperature. Haven't been able to find where they lead to on the power electronics top-board. And traced Pin 9 of CN9006 backup into the topside CN5401 and back to Out3 (Pin 12) of the ISO7241C IC151.

  • At room temperature (at little warm in here, probably 24C) = ~11k
  • At -15C for 10 minutes was ~20k ohms
  • There's no TP point near this component at all.

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Also, the temperature sensors could be I2C. This chip sits between the two SO7241C

1250WSR 1340X 17873 - ADUM1250 - Hot Swappable, Dual I2C Isolators

  • Vdd - Pin 8 - VDD from voltage regulator close to it. That reguklator also powers the SO7241C and has 5V - OutA (Pin 6), OutB (Pin 8), OutC (Pin 10) of the CN5401.
  • SDA - Pin 7 - goes to Pin 10 of CN5401. Also, to Vdd through 47.2k ohm resistor
  • SCL - Pin 6 - goes to Pin 12 of CN5401. Also, to Vdd through 46.7k ohm resistor
  • GND - Pin 5 - goes to GND - Pin 2,4 of CN5401

Checking this because B2840 DTC could also be an I2C failure.

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The only place the i2C chain goes to is over to the isolated sectin of the power electronic's top control board. Goes into another 1250WSR isolator then into a MCP4728A4 chip. - 12-Bit, Quad Digital-to-Analog Converter with EEPROM Memory, start address 0x64 (can be reprogrammed).
Also, I rigged up a multimeter and a camera to see if I could catch a momentary 12V signal given to the AC input’s black relay while attempting to charge. Never happens.

I also rigged up a way to see if UCC28070 is ever getting Vin through CN9006/CN2001’s Pin 7, and again it’s never turning on.

This seems very weird to me. As if the system is acknowledging a fault before ever attempting to draw power. This must reduce the possible set of problems.
That little gold square looks like a fiduciary mark to me--used to line up the board for pick and place robot to populate the board.

Those control boards are too smart--they do power-on selfie test and won't turn ON if there are issues.

For the earlier OBCs from Nichicon they could report much details about faults. For example here is a listing.

After reading the EV-ECU DTCs, the dealer should use the Scan Tool (Consult?) to read down into the Data List from the OBC to get the Internal Diagnostic Code from the OBC / DC Converter box. This gives specific circuit malfunction information that can help give us some idea of which circuits to investigate.

For most of these, the first time it occurs, the OBC will store the code. If it happens again at the next charging, then it throws the code up to the EV-EVU that a malfunction has occurred. This should cause the trouble light on dash to be lit. A few are so serious that a malfunction is indicated at the first instance.
  • 01Output voltage abnormal
    02 Load connection abnormal (main battery not connected)
    03 Output current abnormal
    04 Control power supply voltage abnormal
    06 AC input voltage abnormal
    11 Voltage command abnormal
    12 Current command abnormal
    13 EV-ECU lost
    15 Power factor correction (PFC) circuit temperature abnormal
    16 Temperature in increasing voltage area abnormal
    17 Inside ambient temperature abnormal (boost circuit rectifier temperature abnormal)
    26 Charging current limited (temperature increase)
    27 AC input current abnormal
    28 EEPROM abnormal
    29 Pilot signal abnormal
    30 Electric motor circuit abnormal
    31 Temperature in increasing voltage area abnormal 2
    32 Charging current limited (input voltage decrease)
    33 ROM/RAM abnormal
    35 AD conversion module abnormal
    39 Power factor correction (PFC) circuit output voltage abnormal
    41 Input current sensor 0 point abnormal
    42 Output current sensor 0 point abnormal
    43 Inverter overcurrent abnormal
    44 Rectification overvoltage abnormal
    45 Rectification overcurrent abnormal
i would expect that the Gen2 OBC such as used in the PDM would do even better and have even more fault details, but how to find it?
Oh interesting i've never seen a numbered list before. Where did you find that list?

I was emailing Jim from LeafSpy because in the latest beta update to the app, there are new numbers after the 5-digit DTC code and he mentioned this:
- I emailed him back to define "newer" in hopes it's 2012+.

On the newer Leafs the “-xx” number is a sub code that provides additional details about the error.
The number after “-xx” has a status bit that indicates if the DTC is still active. The other bits I don’t know.
Regards, Jim
And as of right now, i'm getting two different B2840 DTCs with different "subtype".
  • B2840-01 01 CHARGER On board charger VC-74"
  • B2840-96 01 CHARGER On board charger VC-74"
  • U100A-87 08 Charger (this one now pops up very randomnly)
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Those subcodes are from the mitsubishi miev manual with the same Nichicon OBC guts as the laef gen1 units-- same AC rectifier, PFC Boost, H-bridge inverter, HV rectifiers--with all the power components contained in the same epoxy-filled waffle plate mounted to a chilled heatsink.

Somebody like coulomb is needed to reverse the firmware code, but its difficult to even identify the microcontroller. Then to figure out how to read out the code, etc.
Chekcing out the R3022, R3023, R3024 and R3025 i think they are the thermistors in the PFC. R3022 and 3025 were missing from the board when I noticed. Checking to see how important and it seems R3022 isn't important as it goes to Pin 1 of CN2001 but that wire in the connector does not exist. R3025 that was missing, goes to Pin 20 and seems important. THese resistors are very dependent on temperature.

R3022, R3023 - near PFC
  • R3022 was missing from the board and rightfully so, the circuit goes to Pin 1 of CN2001 and it has no wire attached in the connector by design. Otherside is to DC-
  • R3023 is 9.7k at room temperature and goes to Pin 19. Otherside is to DC-

R3024 and R3025 - near the inverter
  • R3024 was missing from board, and is also 9.7k and goes to Pin 2. Otherside is to DC-. Myabe this was a missing thermistor? Replaced with a 9.6k resistor for now.
  • R3025 is also 9k and goes to Pin 20. Otherside is to DC-.

After some tests at -15C
  • Both R3023 and R3024 exhibit the same changes in resistance dependent on temp.
  • At 23C, 9.2k at time 0.
  • At -15C, 20.2k after 17mins
  • Backinside to 23C, 16.2k after 3 mins
  • 13.5k after 6mins
  • 11.5k after 10 minutes
  • 10.88k after 14mins
  • 9.92k after 35 mins

K404 or (K409) B347 - LM358AST - Low-power dual operational amplifiers

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Without charging, the LDO on the PFC/Inverter top-control board gets 15V and outputs exactly 13V. I jumped this to Pin 7 to start the UCC28070 and the AC Input black relay clicks and it closes.
- So, connected J1772 and then jump this pin to start the UCC28070 and the AC input black relay successfully closes at the same time.​
- I'm getting switching 330 to 250VDC at the rectified 1 DC input into the PFC instead of constant 330VD. This is telling me the IGBTs are switching.​
- I'm getting constant 380VDC out of the PFC and in to the Inverter stage at the Drains of the H-bridge IGBTs​
- Still getting B2840-01 and B2840-96 DTC everytime.​
- 0VAC between outputs of H-bridge.​
- Getting only 15VDC, or unstable ~1.7VAC out the H-bridge inverter stage.​
- No current draw.​
- Shutting down charging, I am removing the J1772 plug first to avoid shutting IGBTs off instantly.​
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Sounds like you got lucky and made some findings.
you proved that the PFC can turn on and function if you bypass the controller and jump the relay; => PFC section is likely okay.

it seems there is something in the controller not happy enough to engage the relay, or there is a component fault in that circuit, or there is a missing command.

i don't recommend trying to bypass the gate drives for the H-bridge.

The 15V supply is created on the top board from a 12V supply that is Hot all the time. i think it uses the 12V to make 3.3 and 5V supplies also, and then uses a boost chip to make the 15 from the 5.

In addition there should be one or two more 12 V supplies to the top control board that are only present when Switched by the VCM to send the start command for charging to begin. There will be some additional 3.3 and 5 voltages created from them also. Those need to be checked and verified to be working to rule out culprits. For example the temperature sensors may be getting powered up from the secondary 5V of the Switched 12V.
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it seems there is something in the controller not happy enough to engage the relay, or there is a component fault in that circuit, or there is a missing command.
Just can't find a smoking gun. It's very odd.

i don't recommend trying to bypass the gate drives for the H-bridge.
Not planning on that. I have an IGBT tester coming and an oscilloscope.

So then in the Inverter/H-bridge control circuits we have:
- UCC2895Q - Phase-shifted full-bridge controller with enhanced control logic
- Has 13V Vin​
- There is two of these chips, labelled UCC1-2, from left to right​
- OutA,B,C,D on both chips are similar values.​
- OutA,B,C,D vary between 8V to 13V​
- UCC1 - Vdd - Pin 15 = 13V - should be above 10V to avoid Undervoltage lock out ✅​
- UCC1 - EAOUT - EAN Pin 1, 2 = 13V​
- UCC1 - Out A = TC2 InA = Low In for Q2003​
- UCC1 - Out B = TC2 InB = High In for Q2002​
- UCC1 - Out C = TC1 InA = Low In for Q2001​
- UCC1 - Out D = TC1 InB = High In for Q2000​
- UCC1 - EAP - Pin 20 goes to PC9001 (optocoupler) - Vin. (otherside of board) - ? to be measured​
- UCC1 - SS/DISABLE - Pin 19 - otherside of board - TP9253 - should be > 0.5V, otherwise shut down. = ? to be measured​
- UCC1 - REF - Pin 4 - should be > 5V, otherwise shut down = ? to be measured​
- UCC1 - CurrentSense - Pin 12 - if 2.5V then shut down = ? to be measured​
- UCC1 - Rt - Pin 8 = 105.2kohms​
- UCC1 - DELAB - Pin 9 = 4.3k Ohms - to GND​
- UCC1 - DELCD - Pin 10 = 4.3k Ohms to GND​
- UCC1 - ADS - Pin 11 = 365 ohms to GND​
- UCC1 - CS - Pin 12 = 420 ohms to GND​

- UCC2 = PC6503​
- UCC2 - Vdd - Pin 15 = 13V - should be above 10V to avoid Undervoltage lock out ✅​
- UCC2 - EAOUT - EAN Pin 1, 2 = 13V​
- UCC2 - Out A = TC4 InA = Low In for Q503​
- UCC2 - Out B = TC4 InB = High In for Q502​
- UCC2 - Out C = TC3 InA = Low in for Q501​
- UCC2 - Out D = TC3 InB = High In for Q500​
- UCC2 - EAP - Pin 20 goes to PC650 (optocoupler) - Vin.​
- UCC2 - Ref - Pin 4 - Goes through 4.7k ohm resistor to PC650 (op​
tocoupler) Vin​
- UCC2 - Rt - Pin 8 = 105.2kohms​
- UCC2 - DELAB - Pin 9 = 4.3k Ohms - to GND​
- UCC2 - DELCD - Pin 10 = 4.3k Ohms to GND​
- UCC2 - ADS - Pin 11 = 365 ohms to GND​
- UCC2 - CS - Pin 12 = 420 ohms to GND​
- UCC2 - SS/Disable - Pin 19 - otherside of board - TP9211​
- TC4427AVA0 - 1.5A Dual High-Speed Power MOSFET Drivers
- Has 13V Vin​
- 4 of these chips, which im labelling TC1-4 and from left to right.​
- All Ins and Outs are 0VDC for all four chips. **This is strange, going to remeasure this now knowing the circuits.​
- TC1 - OutA = Low In for Q2001​
- TC1 - OutB = High In for Q2000​
- TC2 - OutA = Low In for Q2003​
- TC2 - OutB = High In for Q2002​
- TC3 - OutA = Low in for Q501​
- TC3 - OutB = High In for Q500​
- TC4 - OutA = Low In for Q503​
- TC4 - OutB = High In for Q502​
- All have 13V Vin​
- There is 4 of these chips, two per H-bridge.​
- From left to right it's Q2000, Q2001, Q2002, Q2003, Q500, Q501, Q502, Q503.​
- HO = 13V, Vb = 13V, and Vs = 13V​
- Vcc = 13V, COM = 0V, and LO = 0V​
- SD - Shutdown Logic Input = ? to be measured​
- Same for all 4 chips.​
- IRS1 - High In Q2000 = TC1 OutB​
- IRS1 - Low In Q2001 = TC1 OutA​
- IRS2 - High In Q2002 = TC2 OutB​
- IRS2 -Low In Q2003 = TC2 OutA​

- IRS3 - Low In Q501 = TC3 OutA​
- IRS3 - High In Q500 = TC3 OutB​
- IRS4 - High In for Q502 = TC4 OutB​
- IRS4 - Low In Q503 = TC4 OutA​
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For example the temperature sensors may be getting powered up from the secondary 5V of the Switched 12V.
Yup, they go through a chip K404 and that is also getting 5V. Havent finished tracing thoe circuits yet for R3022, R3023, R3024, R3025.
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Update: Putting this repair on the back burner as a Leaf came in, and I picked up the engine assembly out of it. Now I have 3NF3D OBC/PDM that works flawlessly with L1/L2 (QC to be tested) which has been dropped into my system already. Will continue to diagnose the problem with broken 3NF7C charger, but it will be much slower from now on. (Swapping chargers out in my setup takes about an hour). I might rig up another functioning system on the bench so diagnosing and cross comparing can be done quickly. I do eventually want to figure out what went wrong with the 3NF7C charger.

Further diagnosing is to figure out why the output of the H-Bridge inverter section is not outputting ~380VAC to the isolation transformers. I have previously confirmed that the Input rectifier and PFC section was outputting ~380VDC properly when the PFC controller chip was externally powered.

Broken Charger Part #292C0 3NF7C - built 2014/03 - March 2014. - Reference No. CE-CN02HEAJB
New Charger: # 292C0 3NF3D - built 2014/04 - April 2014. - Reference No. CE-CN02HEAJB.

Since the engine assembly contained the motor, inverter, transaxle and subframe, I will be selling these components as I have no need at the moment.
- 2015 Nissan Leaf - Traction Motor, Power Head Inverter...
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Good to see your back up and going. Was really hoping to see you solve the problem. You have more persistence than most!
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Found the issue. There was a hairline crack in two of the H-bridge/inverter's 2SK3697 IGBTs. They both failed open, and were impossible to detect with a multimeter until they were desoldered.

Replaced the two broken ones and thoroughly checked for any shorts related to the blown circuit, and replaced a few capacitors that I was unsure about or missing. Put it back together and voila now the OBC works. Still unsure what caused it to fail other than our house's electrical issues (sometimes below 90) or prolonged heat issues.

Anyways, turned out to be a cheap fix, a couple of hours of time to solder, and an overall huge learning experience.
cc: @Electric Land Cruiser

  • The top-side of the charger's AC input stage was working properly and sending 167VDC to the PFC section with two good 8.2ohms ceramic resistors On L1 at ~120VAC. Shouldbe 320VDC when charging at L2 at ~230VAC. A simplified factor of 1.39xAC input.
  • Black relay wasn't engaging because of the B2840 fault. This didn't cause the ceramic resistors to burn up because there was no current being drawn after B2840 being thrown.
  • The PFC section wasn't possible to test in-vehicle while charging, as the control ICs are under this board. But, out-of-vehicle, I verified these had no shorting on the power and IN/OUT pins. Also verified the PFC output voltage which was measured to be 380VDC at the drains of the H-bridge/inverter stage's IGBTs and that was enough to know the PFC was good.
  • The missing resistors I mentioned on the top-side of the board are supposed to be missing in the design, even though the pads are there. Verified with my new OBC and opening it up.
  • Verified 15V and 5V power and GNDs down into the bottom-side of the charger which goes to the bottom-side's top control board.
  • Verified no shorting on basically all pins of the ICs mentioned in this article.
  • A small handheld oscilloscope really changed the game and made it possible to verify the outputs of the UCC2895Q, TC4427AVA0, IRS2113S. Very very carefully.
  • Make use of the proper tips for a multimeter and all the Test Points and pass-through points are easy to access. Rather than stripping the blue coating off every part you test.
  • Found the 2 cracked IGBTs. Desoldered and resoldered new ones in.
  • Retested everything and confirmed uniform values across all similar circuits with consideration of all datasheets.

Thanks @kennybobby for helping understand this massive problem. If anyone takes this repair on, don't rush, and feel free to ask questions. If ever needed, and since my OBC is now on the shelf I can read values off any internal component.

Now off to figuring out my chademo issues, getting a local inspection and a build thread.

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