What type of harness connects the shift selector to the ECU and contains the bi-directional communications connector to allow the transmission ECU to 'talk' to Detroit Diesel DDECsystems, the diagnostic data link (DDL) connector?

What type of harness connects the shift selector to the ECU and contains the bi-directional communications connector to allow the transmission ECU to 'talk' to Detroit Diesel DDECsystems, the diagnostic data link (DDL) connector?

• A. Vehicle
• B. Cab
• C. Chassis wiring
• D. Connector

Answer: (B)

The cab wiring harness. In heavy trucks, the cab harness carries the controls and communication links that live in the cab, including the shift selector’s connection to the engine/transmission ECU and the bi-directional data link used for talking to the Detroit Diesel DDEC system. It also houses the diagnostic data link connector, which is used for diagnostics and ECU communication. The other harness types don’t fit because the vehicle harness covers the entire vehicle, the chassis harness focuses on frame and under-vehicle components, and a standalone connector isn’t a complete wiring system.

The cab wiring harness. In heavy trucks, the cab harness carries the controls and communication links that live in the cab, including the shift selector’s connection to the engine/transmission ECU and the bi-directional data link used for talking to the Detroit Diesel DDEC system. It also houses the diagnostic data link connector, which is used for diagnostics and ECU communication. The other harness types don’t fit because the vehicle harness covers the entire vehicle, the chassis harness focuses on frame and under-vehicle components, and a standalone connector isn’t a complete wiring system.