The early Ford Mustang Mach-E electric motors are affected by a software problem that could lead to an empty 12V auxiliary battery and the inability to drive or even enter the vehicle.
According to The edge article, there is a problem with the software on the drive control module, which prevents the 12V auxiliary battery from charging when the car is plugged in and charging the main traction battery.
In other words, the small 12V battery will only get juice from the main battery (via a DC / DC converter) if you unplug it. This is an obvious error and in many cases will result in an empty auxiliary battery.
According to an official service bulletin submitted by Ford to the National Highway Traffic Safety Administration (NHTSA), it is about cars “Built on or before 3-Feb-2021” (at least several thousand).
Issue: Some 2021 Mustang Mach-E vehicles built on or before 3-Feb-2021 may discharge the 12-volt battery while the vehicle is plugged in during the high-voltage charging process. This may be due to the parameters in the drive control module (PCM). Follow the service procedure to correct the condition to reprogram various modules starting with the PCM. “- service bulletin
Since the Ford Mustang Mach-E is envisaged for software updates over the air (OTA), this should be an easy solution. However, Ford’s OTA is not ready yet (beta phase), so owners of the cars involved should visit dealers at least for the time being to get a new software update.
The service procedure:
- Connect a battery charger to the 12 volt battery.
- Reprogram the PCM using the latest software level of Ford’s appropriate diagnostic scan tool.
- Check the availability of software updates for other modules.
We think that at least for more advanced customers who can check the voltage of their battery and monitor it over time, it is not a necessary update – at least they can in theory wait for the OTA / regular maintenance at the dealer.
Those on the other hand who have been surprised by a dead 12V battery should first recharge (start). This can be tricky, because without the help you can not end up in a closed Mach-E.
There are already videos on how to do this specifically in the case of Mach-E specifically. Actually, any roadside assistance should be able to help.
Several problems with charging the 12V lead-acid batteries had previously affected several electric motors. One of the most recent models with a 12V problem was the Volkswagen ID.3 (solved).
Hopefully, in the future, manufacturers will be more cautious on this topic, including OTA as soon as possible and perhaps gradually switching to higher capacity / higher voltage lithium-ion batteries to improve the auxiliary system overall.