Here is an excellent video from Powerful UK explaining how the MHEV system works on JLR products, as well as basically every other automaker. Simon does a great job explaining how everything works without being overly technical. Worth a watch if you want to learn more about the system!

 

Two weeks ago my DC to DC converter failed and my 2023.5 Defender turned into a brick. There was no warning, no alerts, nothing. The vehicle just stopped and became completely unresponsive. On attempting to restart it briefly showed a warning "Stop safely, Electrical fault detected" before dying again. It wouldn't turn on but interestingly it also wouldn't turn off. With the vehicle seemingly off, you could roll down the windows, but not up, you could unlock the doors, but not lock them. The rear and side lights remained illuminated the entire time and refused to turn off, we could not shift the vehicle out of gear or remove the electric handbrake. The hazard lights were the only thing that actually seemed to work normally. The car was firmly planted in its position absolutely refusing to budge.

Land Rover road side assist was called and the vehicle was towed to the service center (kudos to my service center as they repaired it the same day). What I found interesting was this was a single point of failure and nothing I could do would prevent this from happening, nor was the car moveable in any capacity, it would have been nice to (or at least attempt to) push it out of the way.

To avoid this, as shown in the video, I guess I could drive around with the GAP tool activated which would have shown the battery being depleted and not charging, which would be an indication that something is not right, but realistically who is going to do that.

 

Yes. It's a good video. Got me inspired to check my own. 91% at 4+ years.

It's kind of fun to watch these live values as the car is driven.

 

I need to stop watching Simon. Here I was, thinking now that don't have a diesel any more and the constant monitoring of the DPF, he now chucks my OCD into a whole new parallel universe.