Hi Graham, they seem a bit obvious but maybe it can help, here is the breakdown of the fault code
1. Cable connections between seat switch (S4) and controller (N1:33, N1:38) faulty.
2. Cable connections between pedal position sensor (1B2) and controller (N1:1, N1:32, N1:49, N1:61) faulty.
3. Seat switch (S4) defective.
4. Pedal position sensor (1B2) defective.
Are you sure your clearing the right fault. Is the glow plug light flashing? If so you have an engine management fault and need another lead to connect to the engine ecu. I see fault 104 regularly it doesn't normally cause any issues or display on the dashboard. Is the lightening bolt lit and T104 showing on the display?