| Trailers generally come with a 4 or 5 wire flat | | | | Check the simple things first if all lights act strangely. |
| connector or a seven wire round connector. If your | | | | |
| trailer has an electrical wiring connector this does NOT | | | | 1. Check the wiring connector between tow vehicle |
| mean your trailer has electric brakes. Electric brakes | | | | and trailer. Clean the exposed connectors with a fine |
| are a separate connection. | | | | sand paper or steel wool. Make sure wires have not |
| The purpose of the wiring connection is to match the | | | | been cut or scrapped on the pavement. |
| action of the lights on the tow vehicle to the trailer | | | | 2. Check the ground wire from the connector to the |
| lights. This includes the running (night) lights, emergency | | | | trailer. This wire cannot just be wedged under the |
| flashers, turn signals and brake lights. A four wire | | | | coupler lip. The wire has to be against clean bare |
| connector contains a ground wire (connected to the | | | | metal, with a screw or bolt attaching it to the frame. |
| trailer frame), running light wire (goes to both right and | | | | Preferably a separate drilled hole in the frame for this |
| left trailer lights) and turn signal/brake light wire for right | | | | connection. |
| and left lights. | | | | 3. If only one light is acting up, check the bulb first for |
| If you have a five wire connector, the 5th wire is used | | | | proper connection, Carefully remove the bulb and clean |
| for an electrical solenoid on a hydraulic actuator used | | | | the connectors on the back of the bulb and inside the |
| to stop the brake when backing up. This are | | | | light housing. Check the ground to the frame. This can |
| commonly called a "back up solenoid", "reverse flow | | | | be a short wire of just the bolts holding the light to the |
| solenoid" or "stop flow solenoid". The fifth wire from | | | | trailer frame. |
| the tow vehicle is connected to the reverse lights of | | | | 4. If you have a long bell wire or similar, you can check |
| the tow vehicle. This activates the solenoid when the | | | | the ground at each light. Attach an alligator clip at each |
| vehicle is placed in reverse. | | | | end of a wire that is long enough to go from the tow |
| Most trailer light problems stem from a bad ground | | | | vehicle to the end of the trailer. Connect one end of |
| connection between the tow vehicle and the trailer. | | | | the wire to the vehicle frame, making sure to get a |
| Since there is not a ground wire going back to each | | | | good connection to bare metal. Connect the other end |
| light (very few trailer manufacturers add additional | | | | to the ground on the light. Compare results. If the light |
| grounding wires), the proper ground for each light is | | | | works better, that is the most likely spot where the |
| dependent on the wiring ground from the vehicle to the | | | | ground connection is bad. |
| trailer and the ground connection at every light. | | | | 5. If your lights flash rapidly and not a full brightness, |
| Indicators that you have a bad ground connection are: | | | | you may need a new flasher in the tow vehicle. |
| | | | Consult with a local auto parts store to replace the |
| 1. Weak or dim trailer lights | | | | existing flasher with a HD model. |
| 2. Opposite light dimming when turn signal is on | | | | Remember, your trailer lights tell the traffic around you |
| 3. Running lights go dark when turn signal is on | | | | what you are doing. Improperly working lights are a |
| 4. All lights dim and lightly blink when turn signal is on | | | | hazard to you and everyone driving around you. |