Instruments and controls
Seats and restraints
Detroit Diesel engines
Air brake system
Engine brake Manual gearboxes and hydraulic clutch
SmartShift Freightliner automated gearboxes
Fontaine fifth wheel coupling
Coupling device for Holland trailer
General Maintenance Information
Frame and its components
Heater and air conditioning
Wheels and tires
The Freightliner wiring diagrams are divided by system function. This allows
for many different options or accessory systems to be installed on the same
model truck. Examples for this section are drawn from the diagram below
Checking and cleaning the trailer cable one.
Disconnect the trailer electrical cables from the outlets in the cab.
Inspect the cables and connectors for corrosion and clean if necessary. If the outlet is too corroded to clean, replace it. Freightliner also recommends replacing the wiring harness of the outlet if corrosion has entered the wires and connectors inside the outlet.
IMPORTANT: When using an aerosol cleaner to remove corrosion, be careful to protect any surrounding painted surfaces.
Apply lithium-based dielectric grease to the inside of the connectors, such as Lubriplate FLP DS-ES.
Connect the cables.