Trailer 7 pin plug. What makes the truck register that there is a trailer?

[Joseph DeMeyer]

Hello, 

I needed more reverse light while plowing so I wired two lights into a 7 pin plug(reverse and ground). When I plug it into my 24 nothing happens. When I plug them into my dads 22 the revier light work. When it’s plugged into my truck, the truck doesn’t register that anything is hooked up so it doesn’t send power. Anyone have any idea what is required for the truck to register that it needs to send power?

[tbarn]

Trailering Description and Operation

Trailering System Overview

Begin the trailering system diagnosis with Diagnostic System Check - Trailering. The Diagnostic System Check - Trailering will provide a complete strategy to locate and repair a vehicle trailering electrical fault. Not following this strategy may cause additional diagnostic time and/or misdiagnosis.

The trailering system consists of the following:

• Trailer Lighting, refer to Trailer Lamps Malfunction for additional diagnostic information.
• {JL1} Trailer Brakes, refer to Trailer Brake Malfunction for additional diagnostic information.
• Trailer Battery Charging System, refer to Trailer Battery Charging Malfunction for additional diagnostic information.
• Trailer Detection, refer to Trailer Detection Malfunction for additional diagnostic information.
• Trailer Tire Pressure Monitoring System, refer to Trailer Tire Pressure Monitoring Malfunction for additional diagnostic information.
• Trailer Theft Detection.

7–Terminal Tow Vehicle Electrical Receptacle Pinout

• Terminal A – Trailer Backup Lamp Control
• Terminal B – Ground
• Terminal C – Trailer Brake Control
• Terminal D – Right Trailer Stop/Turn Signal Lamp Control
• Terminal E – B+
• Terminal F – Trailer Park Lamp Control
• Terminal G – Left Trailer Stop/Turn Signal Lamp Control

Connecting Aftermarket Accessories

• Some aftermarket accessories that connect to the X88B Tow Vehicle Electrical Receptacle will be recognized by the vehicle as a trailer connected, even if the accessory is not a trailer. As a result, side blind zone detection, rear park assist, and/or rear cross traffic alert will be turned off anytime the vehicle detects a trailer/accessory is connected.
• Vehicles equipped with U1D/UET have trailer theft detection that constantly monitors trailer connected status when enabled. This is done by randomly pulsing the lighting circuits of the trailer when the vehicle is parked. As a result, some aftermarket accessories may be turned ON/OFF when connected to the vehicle with theft detection enabled.
• Vehicles equipped with U1D/UET use pulse width modulation voltage (PWM) for trailer lighting functions. Some aftermarket accessories are incompatible with PWM and may not function correctly when connected to the trailer lighting circuits of the vehicle.

Trailer Battery Charging System

Trailer battery charging is accomplished through constant battery voltage from the X50A Engine Wiring Harness Junction Block to the X88B Tow Vehicle Electrical Receptacle. Battery voltage is supplied to terminal E at the X88B Tow Vehicle Electrical Receptacle at all times. If equipped, the trailer battery will constantly be charged by the vehicle’s electrical system anytime the trailer is connected. Some trailers require the B+ circuit to the X88B Tow Vehicle Electrical Receptacle for the trailer brakes to function.

Trailer Lighting and Detection With U1D/UET

Note:

• Some trailers utilize 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.
• When a trailer is detected on a vehicle equipped with side blind zone detection, rear park assist, and/or rear cross traffic alert, the vehicle will automatically turn these features off. These features are turned off to prevent false detections due to the trailer obstructing the view of the sensors.
• Vehicles equipped with IOR/1FL do not come equipped with the trailering APP however may still be equipped with a K68 trailer Lamp Control Module.

The K68 Trailer Lamp Control Module is responsible for controlling the trailer lighting on vehicles with U1D/UET. The combined trailer stop/turn signal lamps of the trailer must draw at least 55mA of total current to be detected as a trailer or the Trailer Lamp Control Module will not control the lighting circuits. The Trailer Lamp Control Module receives serial data messages from the K9 Body Control Module (BCM) indicating what lamps have been activated on the vehicle. The Trailer Lamp Control Module responds by applying pulse width modulated voltage (PWM) to the appropriate control circuits for the requested lamps illuminating the lamps on the attached trailer. The Trailer Lamp Control Module constantly monitors for trailer connection status, trailer lighting faults, and trailer theft deterrent purposes. This is accomplished through the lighting circuits of the trailer to determine if a trailer is connected. When a trailer is connected, the Trailer Lamp Control Module senses the trailer connection and alerts the driver by requesting a trailer profile setup through the Trailering App, which is displayed on the infotainment screen. If a trailer is disconnected with the ignition ON, the vehicle will display multiple trailer lighting messages until a trailer is reconnected or the message is dismissed by the user. With the key OFF, the Trailer Lamp Control Module will periodically pulse the lighting circuits of the trailer to verify it is still connected. The lights on the trailer may flash at different intervals with the key OFF depending on which type of lights the trailer is built with. If a trailer is disconnected with the key ON, the vehicle will display a trailer disconnected message until a trailer is reconnected or the ignition is cycled.

Trailer Lighting Without U1D/UET

The K219 Lighting Control Module is responsible for controlling the trailer lighting on vehicles without U1D/UET. The lighting control module receives serial data messages from the K9 Body Control Module (BCM) indicating what lamps have been activated on the vehicle. The lighting control module responds by applying voltage to the appropriate relay control circuits for the requested lamps anytime the vehicle lamps are commanded ON. With the relay coil energized, the relay contacts close and allow voltage to flow through the relay illuminating the appropriate lamps on the attached trailer

[Joseph DeMeyer]

So if I’m interpreting this correctly, there needs to be a draw on the stop/ turn signal of at least 55 mA to be registered as a trailer. If I wire in a couple lights or a couple diode’s or resisters it should have enough draw. Thanks for your help

[EJCarter]

Here is another option...

You could wire them directly to the back-up light wire behind the tail light assembly. I went with these small Rigid LEDs and mounted them in the bumper steps. I know the newer trucks have larger steps, but I'm assuming there will be a suitable rear facing surface. This was a pretty simple install. I wired each light separately to each back up light and attached the ground to a small screw I found tucked up on the backside of the bumper. The wires ran down inside the bed behind the tail lights. All connections were taped up very well with heavy duty electrical tape. I installed these with a T-Tap to see how they would work. I planned to go back and solder them, and then add heat shrink, but you know how that goes ...it's probably been 7 years now with no issues.

 

(Pic with lights also shows Rigid's piece of cardboard from packaging I used as template)   

[64BAwagon]

I changed the backup lights to LED. Problem solved. I got them from Lasfit. Made a huge difference.