Stuck On Coolant Pumps and Completely Drained HV Battery Surprise

[Heima]

Instead of writing a long winded story, I decided to make it short.
If you are messing around with your 12V battery, and for some reason, your coolant pumps spin up to 50% and hold there even after the vehicle is powered off and locked. And if your HV battery now for some unknown reason has absolutely 0% charge and 0 miles range, then you are going to need forscan.
Note, 12v battery disconnecting and reconnecting does not fix this.
Use forscan to reboot the body controller to stop the pumps. Recalibrate the BECM state of charge to get back to the real SOC of the HV battery.
In this crazy state, caused by I believe a multimeter circuit breaker or fuse while measuring currrent drawn on the 12V battery, it was not possible to start the car. Messages on the dash about a depleted battery, and forscan reporting 0kw for ETE. Yet, forscan did report ok voltages for the cels, 3.645 v. So the battery wasn't actually depleted. If I didn't have Forscan, I would have been F'ed.
And clearing DTCs did not fix.

 

[davideos]

Thanks for the tidbit of advice.

 

[TheThing2018]

Recalibrate the BECM state of charge to get back to the real SOC of the HV battery

How do you recalibrate it? By Forscan or by a sequence of manoeuvres (such as brake/power/brake/start/...)?

 

[Heima]

How do you recalibrate it? By Forscan or by a sequence of manoeuvres (such as brake/power/brake/start/...)?

I used Forscan, but I believe the Topdon Topscan can do it as well. I have one of those, but prefer Forscan for the FFE.

 

[hoprocket]

Definitely a good tip. I also once had the coolant pumps get stuck on, albeit in a different scenario. I was trying to bleed the coolant system using Forscan sliders to manually control the pump speeds and valve positions. At one point the pumps stopped responding to commands and were just stuck on. I thought I was in real trouble when powering cycling the car didn't make them stop! Fortunately I used the same body controller reset command and they stopped. Forscan is double edged sword. It can get you in trouble if you don't know what you're doing (like me), but can also save you.