Mark

767 with a hard fail on the left engine EEC (Electronic Engine Control).

Engines with a EEC have a mechanical fuel control. FADEC (Full Authority Digital Control) engines have a HMU (Hydromechanical Unit) to control fuel.

Either way, the EEC or FADEC require external inputs to assure proper engine functions.
  
     

With this problem, the EEC's were swapped between engines. The problem didn't follow.

We put a meter to all external inputs and measured the torque coils and feedback wires to the fuel control.

We found the T1.2 temperature sensor reading open. We verified the wires to the sensor plug were good. Resistance readings directly at the probe still had the open.

After a replacement sensor was obtained, we checked resistance. It read 220Ω.
  
     
  
After the replacement and engine run..... all EEC functions checked normal.