Troubleshooting Trailer Wiring that Turn Signals Cause all Lights to Flash
Question:
All my lights are flashing when signals are on and when I turn on truck lights breaks lock up
asked by: Travis
Expert Reply:
Sounds like your trailer connectors are miss-wired or are shorting out.
What you will first want to do is use a circuit tester like the part # 3808 to test the pins of the trailer connector on your truck for voltage in the correct places. Since I don't know what style of connector you have on your truck you will need to check out the help article I attached that has diagrams for all common trailer connectors.
If the problem is on the trailer you will need to rewire the connector of the trailer to match the diagrams as well. You can use a jumper wire on each connector pin from a vehicle battery to test the pins as well.
It sounds like the blinker circuit and the running lights are shorting out to each other and the 12 volt power circuit is shorted out to the brake output circuit.

Product Page this Question was Asked From
25 Ft 5-Way Trailer Wiring Harness - Wishbone Style - 30" Ground - 5' Auxiliary Wire
- Trailer Wiring
- Trailer Connectors
- Trailer End Connector
- 21 - 30 Feet Long
- Plug and Lead
- 5 Flat
- Optronics
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Article: Trailer Wiring Diagrams
- Article: Wiring Trailer Lights with a 5-Way Plug (It's Easier Than You Think)
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Q&A: Taillight Replacement Option For a Winnebago 170778-01-000 Light
- Q&A: Replacing Trailer 5-Way Connector That has 7 Wires
- Q&A: Replacing 5-Way of Trailer that Has Two White and Brown Wires
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: Trailer Lighting Requirements
- Q&A: Replacing 5-Way Connector with 8 Wires on Boat Trailer
- Q&A: Should Ground Wire of Trailer Wiring Run to Frame of Trailer or Back to Light Assemblies
- Q&A: Trailer Light Kit Recommendation for Ranger Boat Trailer
- Q&A: Do You Need to Run a 2021, 2022 or 2023 Chevrolet Equinox at Certain Times When Flat Towing
- Article: Wiring Trailer Lights with a 6-Way Plug (It's Easier Than You Think)
- Article: How to Tell the Weight Rating of a Trailer Axle