Section 2 Safety & Compliance Electrical System The following are highlights of some of the more common or critical aspects of this system. Electrical harnesses providing battery power and electronic control signals to engine and emissions control/ vehicle OBD components including datalinks may not be spliced. These emissions control/vehicle OBD components include the following: throttle pedal vehicle speed sensor after-treatment wiring If the alternator or battery is substituted, it must meet the requirements of the engine manufacture’s guide- lines. This includes alternator ground voltage drop and alternator ground cable effectiveness.
See the engine manufacture’s guidelines for recommended test procedure. Additionally the maximum voltage differential and the peak-peak voltage differential between the engine ECM block ground stud and battery negative terminal may not exceed 500 mV under any combination of loads or operating conditions. Installation of aftermarket transfer-cases must address the vehicle speed sensor position. The standard posi- tion of the speed sensor is at the transmission tail shaft. When a transfer-case is added it is best to relocate the sensor to the axle side output shaft of the transfer-case. This is typically accomplished by adding a tone wheel into the driveline yoke assembly.
Wiring extensions for the after-treatment wiring are available for relocating the DEF tank from your dealer via Paccar Parts. For relocation of DEF tank, refer to the after-treatment section of this manual. The emission system requires an accurate Outside Air Temperature (OAT) reading in order to properly run its control algorithms. The OAT sensor is located in the driver’s side mirror assembly on Kenworth trucks and is shown in the figures below. If the body builder needs to modify the mirror assembly in any way, it is im- portant the OAT sensor stay positioned on the mirror assembly. Running the vehicle without the OAT sensor connected will cause the MIL lamp to illuminate.
If needed, a replacement sensor can be ordered from your Kenworth dealer. Figure 2-3: West Coast Mirror OAT sensor, located in overmold on mirror harness. 2-6 12/11