What does HEGO mean on the fuse system Ford Falcon 98 EL in main terminal to alt and battery there is a short ground between terms?

HEGO stands for Heated Exhaust Gas Oxygen sensor. It is a type of oxygen sensor used in automotive exhaust systems to measure the amount of oxygen in the exhaust gas, and is typically located in the exhaust manifold or exhaust pipe.

In a Ford Falcon 98 EL, the HEGO sensor is connected to the main terminal of the alternator and the battery. A short ground between these terminals would mean that the HEGO sensor is not receiving the correct electrical signal, which could affect the fuel mixture and cause the engine to run poorly.

If you suspect that there is a short ground between the main terminal of the alternator and the battery, it is important to have the electrical system inspected by a qualified mechanic to prevent any damage to the vehicle's electrical components.