Temperature problem?

[NORTON]

Thanks again!
And now I can totally remove my back seats to get even more space. It's been a two seat cargo hauler for a long time.
I can't remember the last time I had the back seats up.

[drpeshev]

It got cold again and the car stopped again(When I turn it on-only one happens: " Initializing , wait to shift",but NOT Ready). What is temperature-dependent under the hood???! When you put a heater in front of the car , it starts. It doesn't start below 10 degrees celsius (50oF)

[Infinion]

It got cold again and the car stopped again(When I turn it on-only one happens: " Initializing , wait to shift",but NOT Ready). What is temperature-dependent under the hood???! When you put a heater in front of the car , it starts. It doesn't start below 10 degrees celsius (50oF)

Yeah I'm not really sure what is allowing you to start the car under the hood. Instead of a big heater, do you have a blowdryer to direct the hot air more precisely? Maybe you could experiment on what specific section/component under the hood allows you to start the car when you heat it up.

Have you tried preconditioning the vehicle before driving? Press the lock button on your key then hold the precondition button for a few seconds until the hazards flash once. This will activate the car and enable the 2kW battery heater until you start driving.

Have you tried entering Service Mode? This is done by holding the start button for longer than 5 seconds and enables all systems besides driving, which you could use to heat the battery with the 2kW battery heater. After a minute, you can shut the car off and then start the car in normal mode to see if it is drivable.

Where (the Hell) is this resistor
What is battery disconnect unit BDU (12v harness?)

Are you actually talking about R39? If so, it is here


To access this, you have to remove the High voltage battery cover that sits overtop everything.


The battery needs to be disconnected and high voltage service disconnect removed.
Normally you would disconnect the connectors and lower the battery out of the car from below while the vehicle is on a lift....But that requires the help of a proper shop.

I don't know if you can access all the bolt locations from inside, but it is certain that you would have to remove the cloth floor, and I have no idea how to do that without removing it destructively with cuts all around the battery pack in order to create a huge opening. Better if you lower the pack on a big scissor lift table while the car is on a lift of its own. (Find an EV repair shop!).

Here are some pictures of the battery box situated in the vehicle.

https://www.sparktalk.com/threads/2014- ... tures.360/

[drpeshev]

I haven't tried R39 yet , because it is too complicated and not under the hood.When I put a heater in front of the car in the garage and the temperature rises 10oC/50oF there is NO problem.
I tried preconditioning with the remote- not working under 10oC/50oF
Will try Service Mode!
Thank you very , very much

[drpeshev]

R39 changed without lower the battery out of the car

[Infinion]

R39 changed without lower the battery out of the car

BUT NO luck - now is cold again and my spark won't start under 15oC (60F)
Any other suggestions ?
p.s. Is there any chance the car is made only for California hot climate and there is some temperature software restrictions
Thank you very much for helping me , desperate again

Hey drpeshev, that sucks that you're still having problems. Very impressive that you got to R39.

No, the car works in cold climates, it's 6-10ºC where I live and the range is just reduced.


Let's hit PAUSE on investigating the high voltage interlock loop and investigate a few more basic things.

First, have you tested the AGM battery under the hood to see if the voltage is too low on a cold morning? If the voltage is too low, the high voltage contactors won't engage and I don't believe the APM will engage either. The AGM could have a low state of charge, or it could be fully degraded and unable to hold a sufficient charge while cold. That being said, when you add your heater and blow hot air under the hood in both situations, it could increase the available capacity and allow you to run the vehicle. This could be an indication of a dying AGM that needs to be replaced if true.

To get sufficient voltage for initializing the system and getting the car in a "ready to drive" state, do you have any other 12V lead-acid batteries lying around, or clamp-on (jumper) 12V car starters that you could add to or replace the AGM with for TESTING purposes?
A few users have replaced the AGM with smaller batteries and SLA batteries in this thread: viewtopic.php?f=10&t=9274 and it seemed to have worked in their vehicles.

To start, find a voltmeter or multimeter to test the voltage. Report what the voltage is between the terminals

• Voltage while cold,
• Voltage after you've raised the temperature under the hood with your heater, and
• Voltage after you start the vehicle (should be around 14V from the DC-DC auxiliary power module.

A charged battery should be sitting at around 12.6V or higher. If it's somewhere in the 11.5-12.2V range it's getting pretty deeply discharged and should be put on a charger immediately or have its capacity checked (50Ah?) and completely replaced if it has dropped below 11.5V (causes sulfation, huge loss of capacity every time).


Another thing worth checking for are loose battery cables which can cause a voltage drop if they are corroded or don't have proper contact. This would also give you issues so make sure terminals are tight at the battery posts, and also confirm that there is a good connection to the body ground.

Report your voltage findings and we'll start from there. It would be great if it all came down to a dead battery. I'll keep my fingers crossed for you.

[gazik75]

Hello, please help me, what is the catalog number for these parts? R39. I can't start the spark, it gives an error message P0C78

[Infinion]

Hello, please help me, what is the catalog number for these parts? R39. I can't start the spark, it gives an error message P0C78

This thread had to do with examining the interlock loop related to OP's code, or another malfunctioning sensor related to temperature. Your code is unrelated to this, but I can try and help answer your question.

Visit for code explanation
https://www.aboutautomobile.com/Diagnos ... Code/P0C78
I wouldn't try doing anything to the interlock system or trying to find a part number for R39, it will not help you.

Precharge as referenced in the error code involves a low-power resistor and relay that help softly complete the battery connection to the car's high voltage systems when you first START or charge the car. This small resistor-relay combo sends limited power before all the main contactors do, slowly equalizing the voltage between the battery side and the load side where the high-voltage power modules remain in a de-energized state. This is done so that the contactors don't experience wear from the sparking that would otherwise ensue on their metal contacts if you suddenly introduced 350V across them. And this strategy prolongs the life of those contactors astronomically and is typical in all EVs and PHEVs.

This is the precharge process. The voltage difference across those contactors should slowly go from 350V to 0V in a certain amount of time before the main contactors clunk together, and if it doesn't do this in time for whatever reason, you get your error code.

Please see this section of the Dr Kelley's video of this contactor section that explains this much better than I do. The Bolt EV and Volt should use the same parts so it is relatable to the Spark EV.
https://youtu.be/ZBzRKglr95U?t=4802

ANYWAYS TL;DR
Before you replace anything, there are low-hanging fruit solutions.
Could be the 12V battery:

1. Check to see if your 12V battery's connections at the post are firm and not corroded, and if the voltage on the battery is sitting at or above 12.6V
2. Disconnect one of the 12V battery terminals with a 10mm socket and let the car sit for a few minutes to reset all the 12V computers. If the battery was low or dead throw it on an automatic charger or 14.6V until current drops to 10% of your Ah rating or roughly below 5-6A.
3. If your AGM is original, it is most certainly getting weak. That can affect the precharge process because all the contactor coils run on 12V power! Test it if you have the tools, charge it on a 3rd-party battery charger and try again, or get it tested at a shop, and replaced if it's bad.
4. reconnect the posts to your battery.
5. Start the car and report here what happens

I'm not clear on this but the car should do its own testing each time you start it. If it doesn't, you might need to clear the P0C78 code with an OBD II dongle manually.

We can explore other options later. I highly doubt your precharge relay and resistor went bad but if it did, it's not in an easy place to replace and the parts and labor wouldn't be cheap either, so I hope it isn't.

[gazik75]

I completed the entire process of resetting errors. I checked the battery charge at 12.5 volts. After resetting the errors, I disconnected the battery. I turn on the ignition, errors P0C78, P0ABC. P0A0C. U1861. P1E00. I have a question for you: perhaps the absence of motor 94558478 and error U0284 affect other errors. After all, I drove exactly 10,000 ml without this part?

[gazik75]

It's a pity error PС078 covers many other faults that cannot be detected by the scanner, I found the cause of the faulty module that was blocking everything, the repair took a long time