Hi Jason,

There are only perhaps 2 or 3 people on this forum who have any experience with repair and troubleshooting of these specific cars - and they are also on the myimev forum. So to be honest you're much more likely to get help on myimev as this forum while being UK centric is 95% EV drivers and maybe 5% DIY'ers while myimev forum members are heavily DIY oriented people who like to get their hands dirty troubleshooting and repairing and that forum is the best resource I've found online for getting help repairing these cars.

Back in February I had to repair the onboard charger in my 2011 Ion - it had the classic 20 amp fuse in the MCU and two disc capacitors in the onboard charger failure that stopped it charging either the traction battery or the 12v battery. I was able to do this myself relatively easily thanks to the help on myimiev (having an electronics background helps too...) and I was actually forewarned of the problem before it happened to me so as soon as it did happen I was quickly able to diagnose it and knew immediately what it was likely to be and ordered the parts before I even opened it up...

I'm not that far from you (Motherwell) but I don't have any experience of the P1A15 fault apart from casual reading in myimiev a few months ago, and well, coronavirus...

One of the potential causes of P1A15 from what I remember is a faulty pre-charge resistor, however this is located inside the traction battery housing so you'd have to drop and dismantle the traction battery to get at it even to test it. I've had my traction battery out to swap some cells (and took a bunch of photos of the process) and @G.a.r.y has worked on some as well so there is at least that. I'm not entirely sure where in the traction battery assembly the resistor is though as I didn't go looking for it. A faulty air con compressor or PTC heater putting a partial short on the HV bus could potentially also cause P1A15 so it might be worth unplugging them (the two orange cables at the front of the pack) as a quick test to see if the car will then go into READY. (Be careful of the high voltages of course, 360v DC is deadly as you can't let go if you grab it like you can with AC, it's much more dangerous than a 240v AC shock)

I wish you well though and I'm sure with help from the guys on myimiev you have at least a fighting chance of fixing it. After an onboard charger failure in February and a brake vacuum pump failure in June I decided enough was enough and traded mine in on a much younger Leaf as I already have an old Petrol car to exercise my DIY skills.

 

Hello,
I second everything that DBMandrake has written.
Is the error on the car constant or intermittent? Does the same error code return after clearing every time you try to start the car, or is it intermittent? Do you see any other error codes? Is the capacitor voltage always reported as 2 volts? This very low voltage implies that there's no attempt at charging the cap - maybe the EVECU is not pulling in the pre-charge Contactor.
Do you have high-voltage experience, tools, test equipment and PPE to safely work on this problem?
I doubt that you would find general electronics companies that could test the boards removed from the vehicle. Some of the components on the boards can be tested statically with a multimeter, but I think you first need to progress in localising the fault.

 

Thanks for the feedback guys, it's much appreciated. I must say the myimiev forum is probably the most technical car forum I've ever come across- very impressed!

Had heard that the heater and AC units can cause a problem, so I think they would be worth investigation, even just to rule them out.

The oracle that is Kiev seemed to be pointing towards some failed components in the bottom PCB, hence my interest in getting these tested. Seems to be a similar issue to that which affects the DC-DC converter, i.e. failed 50p capacitors etc.

The error is permanent. I've never been able to get the car to go into 'Ready'. If I reset the error code (and I'm quick), I have been able to hear (what I think are) the contactors working. The error generally comes back before I have the opportunity to hear this though.

I've only tested the capacitor voltage once, using Hobdrive. I've read that it's a good idea to measure this with a multimeter and compare the two values. Not 100% where I would be measuring about though.

I've never worked on HV before, but my pair of the Class 0 gloves arrived in the post today, so figured I should be pretty well protected with those and some safety specs. Plan of action would be, disconnect 12v. Wait 5 mins. Pull plug under passenger seat. Disconnect heater/AC. Reconnect plug, then 12v. Test again. If unsuccessful, repeat previous procedure, add in a little extra waiting time to allow big cap to discharge, then remove inverter for closer inspection.

Think this sounds logical, but I would welcome your thoughts!

 

I think your purchase of Class 0 1500v DC gloves sounds like a very good idea. I would also suggest taking a moment to think through every step of any HV procedure before you start.

With an old-fashioned analogue meter set to Ohms you can confirm that the 800uF 450v input filter capacitor in the motor inverter will accept a charge. The meter pointer will initially swing to the right indicating low resistance, then drop back as the capacitor charges ( to the voltage of the meter's internal battery ). You will have to temporarily disconnect one terminal of the capacitor ( which is polarised ) to test it. Note that when an analogue meter is set to Ohms, the black test lead is actually positive.
If you plan to do a dynamic test by measuring the actual voltage across the capacitor as ( or if ) it charges, then again an analogue meter may indicate this faster ( as long as the meter has a 500v DC range and adequate insulation ).
I still suspect that the capacitor is not even attempting to charge, because a Contactor is not closing ( or not conducting ). You can monitor the 12v control signals for the negative, the precharge, and the positive Contactors at connector C-111 of the EV-ECU, under the rear seat. The +12v signal for the negative contactor is pin 106 ( violet ), precharge is 105 ( yellow ), positive is 107 ( red ). Ground is pin 10 ( black ) on connector C-106.
Before each test, clear the fault code and then try to power-up whilst monitoring the contactor drive signal. It may be helpful to rig a 12v LED indicator to each of the 3 signals to be able to see a pulse.

 

Thank you Eddie, that's all really useful information. Appreciate you ask taking your time to write such helpful posts. There's certainly loads of very well informed people out there in the ev community!

Unfortunately, I'm currently self isolating, so it'll be Sunday at the earliest before I get a chance to put it into practice.

I have an old avometer, which sounds like it might be more useful for the tests you've described. I don't have it handy at the moment to check the specs- hopefully it will be up to the job.

I'm guessing a led is preferred to a 12v test bulb as the signal is on for too short a time to allow the bulb to illuminate?

Also is there a sequence that these pins should follow during start-up? Or as long as all get power during start-up that's ok?

Thanks, Jason

 

Jason, an Avo would be perfect! For the static test on the capacitor, the straight Ohms range will do ( check that the internal 1.5v battery is OK ). To measure the cap charging, use the 500v DC range. Clipping the test leads on permanently, rather than holding them, would be safer.
However, I would first confirm that the 12v contactors are being activated. In normal operation the negative contactor should pull in and stay on, then the precharge should pulse ( a second or two ? ) and drop out, whilst the positive comes on and stays on.However, with this fault condition, the exact sequence will depend on how quickly the P1A15 error causes all the contactors to drop out.
A 12v LED across each contactor coil may help to show what happens. I would suggest a set of 5 x red, constant, 3mm, price £1.95 :

https://www.ebay.co.uk/itm/12V-Pre-Wired-LEDs-3mm-5mm-10mm-Various-Colours-Lamp-Wired-LED-9V-12-Volts-UK/262762466125

This test may show that the contactors are trying to close, but it will not prove that their contacts are conducting properly.

 

Thanks again Eddie, I've ordered up the led test leads and a battery for the Avometer. Although having re-read your reply more closely, I now don't think I need the slightly expensive 15v battery....oops!

Info regarding order of the ECU pulses/ order the contactors should come on is very useful, thanks.

Will be sure to feedback with the results of my investigations.

 

Yes, the 1.5v battery is enough for the Ohms range of an Avo; the 15v battery is only needed for the Ohms x 100 range.
It would be possible to place the three wire-ended LEDs nearer to the driver's seat by extending their leads. I think 5 or 6 feet is possible, by using 3 lengths of twisted-pair flex, with each signal wire ( pins 105, 106, 107 ) paired with a grounded wire ( pin 10 ).
To piggy-back these test leads to the pins at connector C-111 of the EV-ECU, I would be tempted to push a needle through the wires.

If this troubleshooting process does not yield any clues, I think it could be repeated using an oscilloscope to check for and get precise timings of the contactor drive signals, whilst monitoring the voltage rise on the capacitor.
Another idea would be to positively drive the contactors in the required sequence, using external 12v supplies, instead of the EV-ECU signals.

 

So, finally managed to get a look at the car this afternoon.

Results were as follows-
Voltage over the big capacitor was 350v. This only lasted for a split second, before reducing to 0v. The cap only charged up on occasions when I could hear the contactors operating. Occasions when the contactors operated were few and far between. I think this was because a DTC (u1113- related to CANBUS) kept appearing even before I'd tried to start. The p1a15 error didn't generally seem to appear every time, but I'm pretty sure it did after I'd heard the contactors activating.

I also monitored the EV ECU pins as suggested. 105 and 106 were definitely working (albeit only when the contactors could be heard). 107 didn't appear to be doing anything, but this could've been due to a bad contact with the test led. I plan to have another go tomorrow and see if I can get 12v on pin 107.

Seems a little odd to me that the u1113 error seems to be so persistent. My initial thoughts had been that this was symptomatic of the p1a15 dtc, but since they don't seem to always appear together, I'm really not sure now!

 

Had another look at the car again this afternoon.
Managed to reliably get the contactors to activate. To do this I need to delete the DTCs. They both come back almost immediately. If I repeat this a few times, I eventually end up with only u1113. If I then switch off the ignition for about 30 secs, I hear a relay click behind the right hand side of the dashboard. If I then turn the ignition, the contactors can be heard.

I then checked the connections of the test leds and monitored the pulses. 105 and 106 can be seen to come on and off, although 107 (the positive contactor doesn't produce a signal).

Ev ECU circuit diagram

I managed to get a video of the LEDs, see below link. Not sure if the flashes are indicative of anything?

Ion ev ecu

I'm starting to think that the ev ecu might be defective. Although, I appreciate that the ECU might not allow the positive contactor to activate if there is an underlying issue.

 

Had another look tonight. Managed to get Hobdrive to read out the capacitor voltage during start up. It showed 344v against a battery voltage of 358v (approximately 96%).

Didn't get a very accurate reading with the Avometer due to the needle dropping away pretty quickly, but I'm thinking that the voltage I measured over the cap was actually 358v (rather than my earlier estimation of 350v).

Now thinking that the issue may be to do with the voltage measuring circuit in the inverter being defective. So, although the capacitor is charging up to battery voltage, the ev ECU is seeing that the capacitor voltage isn't charging fully. Think this is what's causing the p1a15 code to be thrown.

Would welcome any thoughts on my slightly indirect route to this conclusion!

 

I seem to recall some discussion of similar symptoms reported in one of the threads on myimev where the problem was tracked to a faulty voltage divider which measures the voltage across the capacitor. You might have to hunt a bit to find that discussion though.

 

p1a15 is precharge capacitor timeout.

Faulty air con or heater/their wiring can cause it, along with a few other things. Disconnect power to the heater and air con as a first try. Precharge resistor failure is not common, issues inside the dc-dc converter are common.

Cheers.

 

Sorry for the late reply.
The measured brief 350v or 358v across the capacitor is correct. Perhaps that voltage is via the precharge contactor, maybe the issue is due to the main ( positive ) contactor not closing or not conducting? Obviously not easy to read an analogue meter quickly enough, but then again the sampling rate of a DVM means they are slow too. Some digital meters have a PEAK HOLD option ( I've got a clamp-on DC ammeter that does that ).

The U1113 CANbus errors - perhaps bad connections, maybe some connectors or modules were disconnected and removed then re-installed during troubleshooting before you got the car.

From your video, it looks like there is a brief flash on 105 (PRE) ( probably not a fault? ), then 106 (NEG) comes on, followed by a good steady pulse on 105 (PRE), finally 106 (NEG) drops out.
Nothing on 107 -POS- could be the output driver of the EV-ECU for that signal failing, or the ECU decides not to enable POS because it thinks the voltage on the capacitor is not high enough or not rising fast enough. Does that decision already get made during precharge......? If so, then yes, your fault may well be the previously-seen issue of a faulty or over-pessimistic voltage measuring circuit ( the "hybrid" ).
What is the voltage of the 12v battery at the EV-ECU or at the motor inverter? I have read a suggestion that a low 12v is enough to throw the op-amp voltage comparator off balance.

 

Sorry for the late reply.
The measured brief 350v or 358v across the capacitor is correct. Perhaps that voltage is via the precharge contactor, maybe the issue is due to the main ( positive ) contactor not closing or not conducting? Obviously not easy to read an analogue meter quickly enough, but then again the sampling rate of a DVM means they are slow too. Some digital meters have a PEAK HOLD option ( I've got a clamp-on DC ammeter that does that ).

The U1113 CANbus errors - perhaps bad connections, maybe some connectors or modules were disconnected and removed then re-installed during troubleshooting before you got the car.

From your video, it looks like there is a brief flash on 105 (PRE) ( probably not a fault? ), then 106 (NEG) comes on, followed by a good steady pulse on 105 (PRE), finally 106 (NEG) drops out.
Nothing on 107 -POS- could be the output driver of the EV-ECU for that signal failing, or the ECU decides not to enable POS because it thinks the voltage on the capacitor is not high enough or not rising fast enough. Does that decision already get mad e during precharge......? If so, then yes, your fault may well be the previously-seen issue of a faulty or over-pessimistic voltage measuring circuit ( the "hybrid" ).
What is the voltage of the 12v battery at the EV-ECU or at the motor inverter? I have read a suggestion that a low 12v is enough to throw the op-amp voltage comparator off balance.

Hi Eddie,do you have an iMiev or one of the PSA clones. For the PSA clones, I think the U1113 code is permanent and non fatal because they they don't have the remote.

 

Apologies for not getting back with an update for ages. Finally got my inverter board back from the electronics place who had advised there was nothing wrong with it that they could find but said that there might be something that is not working in circuit.

So, in a bit of desperation, I soldered in a 2MOhm resistor as per the attached photo. Pleased to say that upon clearing the codes with hobdrive, the car now goes into Ready! Very chuffed!

Big thanks to everyone that contributed their experience and knowledge (particularly Eddie).

View attachment 140297

 

Hi Civdjh, got the same problem with P1A15. The code is no longer clearing. Hoping to get some scope traces on the three contactor coils that switch on the traction battery to see if any of these are being instructed to activate. I can hear any clacks. It's a 2017 CZero so has the revised MCU & OBC

 

Hi guys. See there's been quite a bit of activity on this thread since yesterday!

Went to move the car today and, whilst it started, it went into turtle mode and pretty much failed to proceed. Read the live data from hobdrive and it showed that the capacitor voltage (when starting) was higher than the battery voltage. This was accompanied by some new dtcs.

My thinking is that my 2MOhm resistor was adequate yesterday (when things were a little bit warmer).

Propose to use a 5MOhm trimming pot to 'adjust' the capacitor voltage back into range. Think it would be wise to route the pot wiring up to the upper plenum so I can easily adjust if I'm out.

Welcome anybody's thoughts on this proposal.

y

 

Hi where did you solder the resistor? I couldnt seem to open your picture. Seems to prove it is the voltage divider that is failing although having the variable resistor seems like an ongoing inconvenience. Is the voltage divider replaceable with one from a dead car or is it part of a larger component?

Cheers.

 

The voltage sensing circuit is part of the board that's in the bottom plenum of the inverter. Problem is, it's coded to the car (not insurmountable). Bigger issue is that there aren't any available at the moment.

The variable resistor would be trimmed to the required value. I'd hope it wouldn't need to be adjusted regularly unless the caps on the voltage sensing circuit deteriorate further.

Resistor soldering location below- it's on the second leg of the IC as per the thread on the imiev forum.

 

Over on mymive forum, havnt some people managed to replace the caps and op amps?

 

There's talk of replacing the caps but don't think I have the dexterity, eyesight or equipment to replace the surface mounted components used- they're tiny!

 

Agreed.

 

I'm not really that aware of the failure modes for these components, but that is certainly the suggestion that they leak and pull down the voltage.

Was purely going by what Kiev had said on the imiev forum- he sounded quite the authority on such things!

The fixed resistor (2MOhm) worked on Saturday, but since weather has got colder, the big cap voltage is now showing as >100% of the battery voltage. Ev ECU definitely doesn't like this fact!

 

I'm not really that aware of the failure modes for these components, but that is certainly the suggestion that they leak and pull down the voltage.

Was purely going by what Kiev had said on the imiev forum- he sounded quite the authority on such things!

The fixed resistor (2MOhm) worked on Saturday, but since weather has got colder, the big cap voltage is now showing as >100% of the battery voltage. Ev ECU definitely doesn't like this fact!

Hi Civjdh, not sure if you have come across this German fo

I'm not really that aware of the failure modes for these components, but that is certainly the suggestion that they leak and pull down the voltage.

Was purely going by what Kiev had said on the imiev forum- he sounded quite the authority on such things!

The fixed resistor (2MOhm) worked on Saturday, but since weather has got colder, the big cap voltage is now showing as >100% of the battery voltage. Ev ECU definitely doesn't like this fact!

Hi Civjdh, not sure if you have come across this German forum discussing same P1A15 issue.
P1A15 Fehler - Problem gelöst - C-ZERO, i-MiEV, iON - Allgemeine Themen • C-ZERO, i-MiEV, iON - Elektroauto Forum (goingelectric.de)
I gather from that discussion that the problem might sometimes lies in the offset drift of the A/D voltage measurement circuit (transformer residual magnetism) and that maybe reprogramming the A/D is possible. Hopefully someone else can read the German thread and better understand the cure to the P1A15 common problem.
regards

 

Hi Freddy, had a read of it courtesy of Google translate and there's definitely some useful info in there. Never thought in my life that I'd be considering recalibrating a integrated circuit.... But what can I say, EVs not only save you money, but they also teach you about electronics!

 

I can speak and read German, but cannot make much sense of the comments in that thread. It doesn't help that the "solution" is only being passed on by private messages.

The discussion about the fault being caused by an over-saturated transformer core that has become permanently magnetized, and which could be fixed by demagnetisation, makes no sense at all. There are transformers on the hybrid daughter-board, perhaps for voltage isolation, but they are pulse transformers with ferrite cores, and this highly permeable material has negligible remanence.

The AD8677 Op-Amp used in the hybrid circuit is already a device with ultra-low offset, ( i.e. it knows when the two inputs really are equal ), and this offset is stable against variations in temperature and time ( i.e. ageing ). Rather than the "MyImiev Forum solution" of trimming the input voltage divider to alter the ratio of measured voltage vs. reference voltage, this new solution biases the output of the Op-Amp by using a 20k variable resistor to offset ( skew ) the pre-existing internal balance in the chip between the two inputs. It is like the old grocer's trick of casually resting one hand on the scales whilst weighing your purchase....

 

P1A15 error update.

With a brand new fully charged battery, dome some further testing.

Going from 'ON" to "START" position with the key, the Negative Contactor switches on, then the precharge, the contactors are clacking, the dash warning HV light comes on
On a 2 channel scope I can see all this.
If I connect the two channels to the Precharge Contactor coils driver output from EVECU and the other channel to the Main Positive Contactor, its never energised. You can see that on attached pic. The Precharge Coil output has a brief pulse then a much longer On period. Is this correct?

 

P1A15 error update.

With a brand new fully charged battery, dome some further testing.

Going from 'ON" to "START" position with the key, the Negative Contactor switches on, then the precharge, the contactors are clacking, the dash warning HV light comes on
On a 2 channel scope I can see all this.
If I connect the two channels to the Precharge Contactor coils driver output from EVECU and the other channel to the Main Positive Contactor, its never energised. You can see that on attached pic. The Precharge Coil output has a brief pulse then a much longer On period. Is this correct?

Sorry the Main Positive coil driver is never energised

 

The PreCharge Contactor coil driver durations are about 200ms for the pulse and about 1000ms for the main on period.

I'm guessing this is some sort of logic check to make sure the Precharge Contactor is not welded shut?????

 

The behaviour that you have recorded ( a brief pulse on the Precharge contactor followed by a longer "On" period ) corresponds to what was seen by Civjdh in post #11, when he was using LEDs, rather than a 'scope, to indicate the status.

 

@freddym

Your scope has confirmed what the fault code suggests - negative and pre-charge contactors are being powered however the ECU is not happy with the voltage across the capacitor being correct within the specified amount of time so aborts instead of engaging the positive contactor.

Is it possible for you to put the scope on the HV out of the battery pack ? You could measure this on the 20 amp fuse inside the MCU inspection hatch, or at one of the cables for the heater or A/C compressor.

Be aware that the HV system is fully isolated from the ground of the car - you cannot connect your scope ground to both the 12v ground and HV negative at the same time as you will cause the HV system to fail the isolation test when it checks the insulation resistance between the HV system and normal electrical system. The entire HV system including battery, motor, inverter etc "floats" relative to the chassis with opto isolators / transformers etc being the only connection between the two systems. (Even the CMU's in the battery pack use opto-isolators for the can bus signals)

You could connect a battery powered scope (I assume yours is?) to the HV negative and MCU fuse (or just across the PTC heater plug) and use a simple opto-isolator circuit to connect another channel to the pre-charge contactor relay coil if you want to look at the relative timing of the contactor and HV voltage rise although I'm not sure the relative timing is that important - the HV voltage rise curve alone is probably all the info you need.

It would be very interesting to look at the HV voltage charge curve on a storage scope - how high does the voltage go, (relative to actual battery voltage) how long does it take to get there, and indeed does it rise at all! This would help confirm or rule out a number of possibilities.