Measure the resistance between the main fan relay 2 terminal and ECM connector.
Connector & terminal
Euro 4 model
(B135) No. 27 — (F27) No. 22:
Euro 5 model
(B134) No. 32 — (F27) No. 22:
Is the resistance less than 1 Ω?
Repair the open circuit of the harness between main fan relay 2 terminal and ECM.