Code: 77 Internal ECM supply voltage (8V) is too high.
Condition: ECM detects that the voltage at ECM connector 2, pin35 is above 8 volts.
Code causes: Faulty ECM. ECM connector 2, pin 35 is/was shorted by an external 12 volt source. Internal circuit short to 12 volts.
NOTE: Connector 2, pin 35...