How to Install a Trailer Light Connection on a 1999 Chevy

A properly installed trailer wiring harness is a necessary piece of safety equipment when towing a trailer.

Installing a trailer wiring harness on a 1999 Chevrolet Silverado is a simple procedure provided you have the appropriate tools. Check that you have the correct wiring harness for the trailer you intend to tow. There are several different types available, including a four-pin harnesses for smaller trailers, five and six pin harnesses, and seven-pin harnesses. The latter are intended for lsuch arger trailers as boat trailers, RV trailers and horse trailers. These trailers come outfitted with electric trailer brakes.

Things You'll Need

• Trailer light T-connector
• Medium-sized Phillips-head screwdriver

Instructions

1. Remove the tailgate for easier access and then remove the Chevrolet Silverado's driver side taillight using the Phillips-head screwdriver. Use a magnet to hold the screws so that they are not lost.

2. Unfasten the wires from the wiring harness that attaches to the taillight housing by pressing down on the harness release mechanism on the harness' plastic casing. Set the housing aside with the lens facing up to avoid scratches.

3. Install the trailer light T-connector into the vehicle wiring harness. There are three connections on the T-connector. Because it is application-specific to the 1999 Chevrolet Silverado, only one side of the T-connector will fit into the wiring harness correctly. Do not force it if it does not fit.

4. Install the vehicle-side trailer wiring harness into the T-connector and route the trailer-side connector down through the body of the truck and around the plastic guard at the bottom of the bedside until it can be seen underneath the vehicle

5. Re-install the Chevrolet's brake light by connecting the T-connector to the brake light housing's wiring. Fit the tail light housing back into place and replace the screws.

6. Fasten the trailer end wiring harness to the underside of the vehicle using plastic zip ties so that it cannot drag on the ground. Leave approximately 16 inches of loose wiring so that it can easily reach the trailer wiring harness without stretching.

Tips & Warnings

• Use additional plastic zip ties to keep wires tidy. Using a strong U-shaped magnet on the inner bumper will help keep the wiring harness out of sight and clean when not in use.

• Always check the operation of your trailer lights before attempting to tow a trailer. Test the turn signal operation and brake light operation as well as any running lights on the trailer. A routine safety check before towing can prevent dangerous situations before they occur.

References

• "Haynes Repair Manual: 1999-2006 Chevrolet Silverado, GMC Sierra; 2007