B4: Check Core to Core Insulation

with connectors FC025, FC026, BT007 and BT008 disconnected measure the insulation resistance between FC026/013 and FC026/014.

Is the resistance > 10M OHM?

Yes
Go to B5

No
Inspect harness/connectors FC025, FC026, RH001, BT002, BT007 and BT008 for corrosion, damage, bent or pushed back pins. Repair as required and test the system for normal operation.