Body Builder Wiring Diagrams | Volvo Trucks USA Cutting into an OEM harness will void the warranty of the harness, should it be incorrectly used to supply power to PTO equipment. Be sure to consult with your local Volvo dealer when ordering trucks to ascertain proper connectors are supplied when the vehicle is manufactured.Founded Location: Gothenburg, Sweden VOLVO VN770 Problems - 1999 VOLVO VN770 Electrical System Jul 16, 2002Electrical System Problem on the 1999 VOLVO VN770. Car problem(s) with the 1999 VOLVO VN770 database includes information received by NHTSA from consumers either directly or as recorded by the Vehicle Safety Hotline. loss of guages volvo - Electrical - Let's Truck I have an 03 volvo purchased about a year ago from a friend I have had this truck to volvo twice he had it in the shop 5 times for this problem. My brothers Volvo had a similar problem. The wiring harness that goes around the back of the engine had rubbed on the bell housing. He respliced all the bad wires and fixed all his problems.