Greetings. I can't locate the disconnect wire for the auto timing advance. In order to set the timing on this Chevrolet 7.4L Gas motor, the auto timing advance or EST wire needs to be disconnected but I cannot locate this wire within obvious sight anyway. On GM passenger vehicles for this year, the wire connector is within the firewall harness and is usually fairly easy to locate but on the Motor home I am unable to locate it and it has to have one. Does anyone have an idea where this disconnect is located?