Volvo Electrical issues/ Abs Light

[Copper]

Hello everyone this is my first post so first I'd like to say thank you for all the help I received from this website over the last year, Truly thank you very much.



My question today is in regards to my 2006 Volvo vnl 300 with an isx cm870. It currently has an ABS light on and the code that is showing is "Sid 251 fmi 4" a low battery voltage code. I've completely checked all connections at the Bendix Ec-60 Abs ECU and have actually replaced that ECU. it is still showing the same code. All connections at the battery appear to be correct. I'm fairly certain the issue is wiring related but I have no idea how to test, troubleshoot, or trace this problem. I have attached a screenshot of the codes currently showing on JPRO. Any help or guidance in the right direction would be much appreciated.