If the trailer lighting on customers’ trailers connected to some 2019-2020 Silverado and Sierra models does not operate as expected, such as inoperative lighting, improper trailer detection, or intermittently flashing lights with the vehicle off, the cause may be related to either the trailer or the truck. (Fig. 11) Proper diagnosis requires determining the operation of the trailer wiring as well as the components on the truck.
图11.
2019-2020 Silverado and Sierra models equipped with the in-vehicle trailering app (Trailer Information Indicator, RPO U1D) (Fig 12) use the K68 Trailer Lighting Control Module to control all trailer lighting as well as additional features like trailer detection, trailer theft alert and trailer lighting circuit diagnostics, such as trailer bulb out detection and over-current.
图12.
2019年与2020型号
2019型号采用RPO U1D控制拖车照明通过脉冲宽度调制（PWM）电压。拖车公园和停止/转向信号灯控制电路必须绘制至少55mA的总电流以被检测为拖车，或者拖车照明控制模块不会将照明电路控制到拖车。
2020型号用RPO U1D控制拖车照明通过脉冲宽度调制（PWM）电压仅对止动/转向信号和备用灯。公园灯使用内部印刷电路板（PCB）继电器来控制停车灯电路，为停车灯提供额外的输出电流。如2019年型号，拖车停止/转向信号灯控制电路必须绘制至少55mA的总电流要被检测为拖车，或者拖车照明控制模块不会将照明电路控制到拖车。
拖车灯闪烁
One lighting issue that may concern customers is how often the trailer lights flash as part of the trailer detection and/or trailer theft features. The Trailer Lighting Control Module periodically pulses the lighting circuits of the trailer to verify it is still connected when the vehicle ignition is off.
如果停放当车辆停放时的周期性拖车灯对客户感到令人反感，请参阅关于拖车照明控制模块的校准更新的信息的公告＃20-NA-198。更新完成后，拖车灯将仅在拖车盗窃功能关闭时每42分钟闪烁一次。如果在拖车应用设置中打开拖车盗窃警报（图13），则拖车闪光的定时不会随着系统需要连续监控拖车连接而变化。
图13.
拖车模拟器测试工具
要确定拖车照明控制模块的正确操作，请将EL-52641拖车模拟器测试工具（图14）连接到卡车的7路连接器。拖车照明控制模块将检测到测试工具并使能拖车照明输出。通过连接的工具，打开车辆点火以操作所有灯光：PARK，LT / RT转动，停止和反向。如果测试工具上的灯照亮与车辆上的灯的相关性，并且在驾驶员信息中心（DIC）上显示任何DTC或警告消息，则该卡车通过设计而运行，不应对组件执行修理在卡车上。
图14.
TIP:When the vehicle ignition is turned off while the Trailer Simulator Test Tool is connected, the trailer lighting LEDs on the tool may flicker/flash randomly. This is normal and is part of the Trailer Lighting Control Module’s trailer detection/trailer theft feature.
Trailer Wiring
具有非常差的条件的接线的拖车可能导致拖车照明电路的几个DTC以及DIC警告消息。在一些情况下，差的布线甚至可以在车辆上打开拖车照明控制模块熔断器F74UA或F82UA。如果发生这种情况，请验证客户的拖车接线（如果可用）是否处于良好的工作状态。如果卡车在使用拖车模拟器测试工具后正常运行，则该原因与拖车一起使用。拖车相关的照明问题不受保修范围。
以下是一些可能帮助客户/拖车供应商了解并更正任何与预告片相关问题的提示。
- Some trailers use a trailer-mounted control module to operate some or all of the trailer lights. These trailers may use the B+ circuit from the trailer connector to power the trailer lighting circuits. These trailers may not always be detected by the Trailer Lighting Control Module and may set faults. Load resistors could be added in parallel to the detectable lighting circuits of the trailer to increase current draw. Another option is to rewire the trailer to eliminate the trailer-mounted control module and have the circuits wired directly to the trailer lamps.
- Some non–DOT approved LED lamps may not draw enough current for the Trailer Lighting Control Module to detect a trailer when connected and, as a result, the Trailer Lighting Control Module will not enable the lighting circuits to the trailer. Changing one or more trailer lamps on the detectable circuits to incandescent bulbs or DOT-approved LED lamps will increase current draw while maintaining full functionality of the Trailer Lighting Control Module. Adding a load resistor in parallel to the detectable lighting circuits of the trailer also will increase current draw.
- Some aftermarket accessories, such as trailer-mounted cameras, are incompatible with PWM voltage and may not function correctly when connected to the trailer lighting circuits of the vehicle. The lighting control circuits can be wired to control a relay, in which the relay will provide stable voltage to the customer’s aftermarket accessory.
有关拖欠照明的其他信息，请参阅＃pit5747a和bulletin＃20-na-198。
- 感谢凯文未成年人
