1994 international 9400 engine brake failure

Where was the short and what did you do to repair it?

 

What engine?

 

By fuse you probably mean circuit breaker is hot as a fuse would blow. Is the relay marked as being engine brake? Have you swapped the breaker and relay with another? When you say you fixed the short exactly what was it doing before? Short or open circuit? You replaced the ignition breaker before but now the jake breaker is getting hot? Sorry for the load of questions but I gotta go.
Go back and look at anything you messed with working on it. Look for a wire tightened under a panel or problems where you replaced parts. The real problem could be what caused your switch problem and just got worse. Process of elimination: Easiest things first. Unplug the 3 wires under the right side of the valve covers. Breakers OK? Look inside. Breakers still hot unplug the switch etc.

 

There's no such thing as Cummings.