Swapping OBC's as diagnostic - safe?

[coulomb]

the good car charges with the "bad" OBC, the bad car doesn't charge with the "good" OBC.

So that sounds like it's a problem with the car. So that's possibly harnesses/cables, J1772 socket, or fuses/relays.

 

[MickeyS70]

I think I may try towing it to a Chademo.

Tow it around the block in Ready, regen in C or D will charge it…

 

[jpr]

Tow it around the block in Ready, regen in C or D will charge it…

True... I'll give that a shot when I can recruit a friend.

I checked over all the relevant relays and fuses last night and everything checked out good. My latest theory of the case is that it's a low (again, 3.47-3.51 cell voltage) SOC and thus charging is prevented. The J1772 socket is clean and all pins are straight.

Only piece I haven't looked over fully yet is the wiring harness - but I've not seen any damage on the wiring I've seen while pulling or reinstalling the pack, crawling under the car, etc.

 

[MickeyS70]

My latest theory of the case is that it's a low (again, 3.47-3.51 cell voltage) SOC and thus charging is prevented.

If the voltages reported are steady in the range above then AC charging should be possible. However a low SoC can exacerbate CMU ‘blips’ (as described in post #16) therefore it might be a good idea to monitor cell voltages during a failed charge attempt.

 

[jpr]

My lovely partner helped me drag the sick car a few miles with the good car and we got enough charge in the pack that the battery gauge now shows one flashing bar. I monitored cell min/max voltages and they showed a reasonably consistent spread of 0.03 or so as we charged it, now up to 3.71 or so.

Still low, but I'd expect it to AC charge now - which it doesn't (again, testing on an EVSE that works with my other EV's). Monitoring cell voltages while attempting to charge shows no change - the EVSE handshake appears to be the point of failure here, so that's not surprising.

Browsing a few other forum posts, it looks like water in the air conditioner compressor can cause havoc but can safely be disconnected - may try that next.

 

[MickeyS70]

Still low, but I'd expect it to AC charge now - which it doesn't (again, testing on an EVSE that works with my other EV's).

Do you use the same cable? edit: forget that, if it works with the other IMiev it must be ok

Monitoring cell voltages while attempting to charge shows no change - the EVSE handshake appears to be the point of failure here, so that's not surprising.

There is a direct connection from the charge socket to the EV-ECU, might want to bell it out using the schematics in the service manual.

Browsing a few other forum posts, it looks like water in the air conditioner compressor can cause havoc but can safely be disconnected - may try that next.

I know you mentioned this already but have you checked for active DTCs when trying to charge, the OBC only transmits when active or starting up?

 

[kiev]

You're balls deep in the pool looking inside OBCs and diodes and wiring stuff, but what DTCs are showing up?

What error pattern of the LEDs are showing on the EVSE?

Oh it looks like Mickey beat me to it.

Get the codes, then you can know where to look. e.g. if you have a HV error due to leakage at the AC compressor (culprit), then the car won't charge (symptom).

 

[jpr]

You're balls deep in the pool looking inside OBCs and diodes and wiring stuff, but what DTCs are showing up?

Well, that's what started this - there are no relevant codes as far as I can tell.
B1108 - electric heater fail 1
U1104 - SAS CAN timeout/Not equipped
U1111 - Display CAN timeout/Not equipped
U1113 - MiEV Remote CAN T/o /Not equip
U1116 - KOS CAN timeout/Not equipped
C1912 - Tyre air pressure low, Tyre1
C1932 - Tyre air pressure low, Tyre3
C1942 - Tyre air pressure low, Tyre4

What error pattern of the LEDs are showing on the EVSE?

Power is on, "charge" is flashing (instead of "steady"), 12A or 8A mode selected.

Get the codes, then you can know where to look. e.g. if you have a HV error due to leakage at the AC compressor (culprit), then the car won't charge (symptom).

That'd be cool! I'm not seeing that, maybe someone else has a different interpretation.

Do you use the same cable? edit: forget that, if it works with the other IMiev it must be ok

Yessir

There is a direct connection from the charge socket to the EV-ECU, might want to bell it out using the schematics in the service manual.

Will do!

I know you mentioned this already but have you checked for active DTCs when trying to charge, the OBC only transmits when active or starting up?

I just tried - no different from the DTC's I see when not charging. Which doesn't seem like a massive surprise, I know the OBC is good (I left them swapped between the cars) and it's also not progressing a charge past the handshake.

 

[MickeyS70]

Ok, all points to the car not ‘realising’ you want to charge it, we know it's not the EVSE, the cable or the OBC itself, therefore what's left is as @coulomb pointed out in post 21:

- just connect the EVSE cable on the car side (if its tethered turn off EVSE), try to start the car, does it show the red charging symbol?
- check fuse 11 (10A) in the motor compartment
- check charging relay A-06X
- check all connections between charging socket, EV-ECU, OBD and 12V system.

 

[kiev]

B1108 - electric heater fail 1

Here is a troubleshooting page for that code; i don't remember if it is a fail-safe code or if it disables the HV. It has quite a few possible causes.

pdf of TSB for B1108

Do you have full fluid supply in the heater system?

Do you have the heat switched ON? If so turn it OFF and clear, then read the DTCs again to see if it persists.

Does the car start to READY and runs and drives okay?

 

[coulomb]

It might be worth disconnecting the heater, IF you can do that safely. Like the air conditioning, a fault with it might stop the contactors from coming on. With no contactors, you can't charge the main battery.

 

[MickeyS70]

I would have thought if a heater/AC issue would prevent the contractors from coming on, @jpr would not have been able to charge the car by towing it (post #25)?

 

[jpr]

Ok, all points to the car not ‘realising’ you want to charge it, we know it's not the EVSE, the cable or the OBC itself, therefore what's left is as @coulomb pointed out in post 21:

- just connect the EVSE cable on the car side (if its tethered turn off EVSE), try to start the car, does it show the red charging symbol?
- check fuse 11 (10A) in the motor compartment
- check charging relay A-06X
- check all connections between charging socket, EV-ECU, OBD and 12V system.

Spent some time on this just now -
1) Connecting the EVSE to just the car (and not the wall) and trying to start the car shows the red charging symbol on the dash instead of going to READY mode.
2) Checked, good
3) Checked, good
4) That I'm still working on. There is no obvious damage to any connector or wiring that I've yet seen, though.

Here is a troubleshooting page for that code; i don't remember if it is a fail-safe code or if it disables the HV. It has quite a few possible causes.

pdf of TSB for B1108

Do you have full fluid supply in the heater system?

Do you have the heat switched ON? If so turn it OFF and clear, then read the DTCs again to see if it persists.

Does the car start to READY and runs and drives okay?

Thanks for the link. I ran through the TSB up to the steps that require the MUTIII (which I don't have) and found no issues. It's worth noting that the heater and AC both *work*. The heater makes heat, the AC makes cold. I do have full fluid in the heater supply, it cycles fluid around, hot (or at least warm) air comes out the vents after I've had it on for a few minutes, just like the other car.

With the heater off (select green dot on the temp selector, turn fan off), if I clear the code, shut the car off, and restart it, the code does come back - as as Stored code. Odd. May have something to do with some startup check that isn't working.

The car does start to READY and run/drive.

It might be worth disconnecting the heater, IF you can do that safely. Like the air conditioning, a fault with it might stop the contactors from coming on. With no contactors, you can't charge the main battery.

I decided to try this - still wasn't able to charge. Then again, to Mickey's point, I get contactors closing, so maybe disconnecting the heat or AC is a red herring anyway.

 

[MickeyS70]

The EV-ECU is VIN coded, therefore swapping it won’t work and I think it will also prevent charging (or does it?)

If the signal wire continuity test doesn’t show anything out of the ordinary it might be worth a try even if just to see if it throws any OBC related DTCs?

 

[kiev]

From what i understand, if there is a fault in the AC Input Section of the OBC, then it will fail to charge and there will not be a DTC reported. The OBC just sits there and times out and the EVSE shuts off its internal relay.

The PFC chip is monitoring the AC input right before it enters the waffle plate at the L and N solder joints.

There is a thread for OBC troubleshooting.

 

[MickeyS70]

From what i understand, if there is a fault in the AC Input Section of the OBC, then it will fail to charge and there will not be a DTC reported. The OBC just sits there and times out and the EVSE shuts off its internal relay.

The PFC chip is monitoring the AC input right before it enters the waffle plate at the L and N solder joints.

There is a thread for OBC troubleshooting.

@jpr swapped OBCs and the fault stayed with the car (post #20), therefore I don’t think it’s an OBC problem?
If you get around 14.4V across the battery terminals when ready, it would mean the OBC’s DC/DC section is ‘awake’ and the issue most likely EV-ECU related

 

[jpr]

@jpr swapped OBCs and the fault stayed with the car (post #20), therefore I don’t think it’s an OBC problem?
If you get around 14.4V across the battery terminals when ready, it would mean the OBC’s DC/DC section is ‘awake’ and the issue most likely EV-ECU related

That's correct - OBC is known-good now. I do get about 14.4 across the battery in ready mode.

Does anyone know if it'd be safe to swap EV-ECU's between cars? I'm less concerned over whether it's VIN coded, more concerned if I have a strong risk of bricking the EV-ECU from the good car or needing a dealer to reprogram it when I swap back.

Happy to try this if it's at least reasonably safe.

 

[MickeyS70]

Does anyone know if it'd be safe to swap EV-ECU's between cars? I'm less concerned over whether it's VIN coded, more concerned if I have a strong risk of bricking the EV-ECU from the good car or needing a dealer to reprogram it when I swap back.

The EV-ECUs are from identical cars, I’d say (unless proven otherwise) there shouldn’t be any issue apart from a VIN mismatch.
Maybe swap the one from ‘problem’ car into the ‘good’ one, if it still charges then there is nothing wrong with the EV-ECU, however if it doesn’t, it’s either faulty or the VIN discrepancy prevents it from functioning correctly; check DTCs

 

[jpr]

The EV-ECUs are from identical cars, I’d say (unless proven otherwise) there shouldn’t be any issue apart from a VIN mismatch.
Maybe swap the one from ‘problem’ car into the ‘good’ one, if it still charges then there is nothing wrong with the EV-ECU, however if it doesn’t, it’s either faulty or the VIN discrepancy prevents it from functioning correctly; check DTCs

They're almost identical - the good car doesn't have CHAdeMO but the bad car does. Anyway, I'll give this a shot - good thinking on putting the bad ECU in the good car.

 

[coulomb]

I would have thought if a heater/AC issue would prevent the contractors from coming on, @jpr would not have been able to charge the car by towing it (post #25)?

Yes, agreed.