Questions & Answers (13)
Hello, Iain! Yes, this works on any vehicle equipped with a 4-flat trailer harness. Please contact your local U-Haul Hitch Center if you need the proper wiring installed on your vehicle. Thank you!
Hi, Bob! Yes, please contact your local U-Haul Hitch Center to schedule an installation appointment. Thank you!
Hi, Robert! Please visit your local U-Haul Hitch Center to determine the correct, vehicle-specific 7-way parts. Thank you!
Hello, Pac! Here are the wiring instructions:
- Determine a suitable mounting point on the tow vehicle for the adapter. Make sure that the trailer's wire harness has adequate length to reach this point and mount the adapter.
- Plug the 4-flat plug of the adapter onto a 4-flat plug extending from the vehicle. This will provide tail light, left and right turn functions.
- Locate a grounding point near the adapter such as the vehicle's frame or cross member. Clean dirt and rustproofing from the area. Secure white wire with the eyelet (do not drill into vehicle floor or bed).
- Connect remaining wires by crimping yellow connectors (see image above for a diagram of wire locations).
- Note: white wire in 4-flat is not connected to the 7-way adapter. The large white wire must be grounded to assure proper trailer light function.
Hi, Ed! The 13321 is a universal, pre-wired 7-way trailer connector designed to plug into a vehicle's existing 4-flat trailer harness.
For more information on vehicle specific 7-way connectors, please visit your local U-Haul Hitch Center. Thank you!
Hi, Richard! Once plugged in and white ground wire grounded, your trailer will receive turn signal, brake lights, and running lights from the truck 4-flat.
If you require further assistance, please contact your local U-Haul Hitch Center. I hope that is helpful!
Both 13321 and 47185 will adapt your 4-flat to a 7-way spade.
Tech tip: The 13321 & 47185 12 gauge white ground wire must be grounded to the vehicle for proper lighting.
The 13321 12v trailer battery charge line (black wire) must be ran to the vehicles battery with an in line circuit breaker (U-Haul part 13520 or 13530) separate from the 4-flat module battery feed.
The 13321 center auxiliary post (yellow wire) is more commonly connected to the vehicles reverse light for releasing a boat trailers reverse lock out solenoid. However, can be used as another 12v source if needed by running an additional wire and in line circuit breaker to the vehicle battery.
4-flat provides Stop, Turn and Tail lights. White wire (Ground) - Connects to a clean surface on the vehicle frame. Black Wire (charge line) - Connects to vehicle battery with in-line breaker, most commonly used to charge trailer battery. Blue Wire (brake control out put) - Connects to vehicle brake controller out put wire. Yellow (Auxiliary) - Most commonly connects to the vehicle reverse light to release trailer surge brake when backing up.
"The 13321 4-flat provides the 7-way with stop, tail and turn. White wire - Common ground. Blue Wire - Electric brake. Black Wire - Battery charge. Yellow - Auxiliary. (more commonly for reverse light). If you are not getting any trailer lights after plugging in the 4-flat and grounding the white 10 gauge wire, please schedule an appointment with your local U-Haul hitch professional who can quickly diagnose and repair your wiring issue."
"The white wire will need to be grounded on the vehicle to function properly." ... as noted by our hitch pro.
Our hitch pro writes: "13321 is designed to adapt the 4-flat vehicle end to a 7-way flat pin connector. If you are planning on towing a U-Haul trailer and your vehicle is equipped with a 7-way flat pin connector, please use U-Hauls 47335 7-way to 4-flat adapter. "