Endeavour Terminal 30 Issue

I also drive a Ford Endeavour, and I had a similar problem last year. By 'Terminal 30' I assume you mean the direct battery voltage feed used for critical systems? If so, this could be a significant voltage drop somewhere. Have you checked the main fuse box for any signs of corrosion or loose connections? A short circuit is also a possibility. Check the charging system too.

Thanks for the quick reply! Yes, I meant the direct battery feed. When you say 'main fuse box', are you referring to the one under the hood or inside the cabin? Also, how exactly did you pinpoint the short circuit in your case? Any tips for testing the charging system?

In my case, the under-the-hood fuse box was the culprit. Some dampness had made its way inside, causing corrosion. I didn't have a short circuit so I can't comment on that, but it is possible that one of the ECUs is not shutting down correctly causing a voltage leak when parked. Given the Terminal 30 error and start problems, it might be worth taking it to a workshop to check if the battery drain is too high with a proper ammeter.

Thanks a lot for your help! I followed your advice and brought it to a trusted workshop. Turns out the battery was indeed defective and needed replacing. Also the drain test revealed excessive voltage being leaked by the ECU. After changing the battery, the mechanics re-flashed the ECU's software, and that solved the issue. The bill was 290€.