Pollak 7WB-143V
7-blade to 4-flat flexible adapter
Connect a compatible 4-flat trailer harness to an existing 7-blade towing socket through a flexible lead.
View exact Pollak productPollak 7-Blade Wiring: 4-Flat, 5-Flat & Circuit Tester Guide
A 7-blade tow-vehicle connector can be used with different trailer plug formats, but a plug adapter, a dual-output connector and a circuit tester are not the same accessory. This guide compares three Pollak parts by the connection they make and the problem each is intended to solve.
Start with the plug that is actually on the trailer
4-way flat
A common trailer-light connector. If the vehicle has a compatible 7-blade socket, the flexible 7WB-143V provides a matching 4-flat trailer connection.
5-way or 4-way flat
7WB-178PFV provides dual 5-flat and 4-flat outputs from a 7-blade vehicle-side interface. Verify the installation and available tow-vehicle circuits.
Diagnose the socket
7WB-199PDV is an LED circuit tester for the vehicle's 7-blade socket. It does not change connector type or substitute for a proper trailer wiring inspection.
Connection safety: An adapter does not create functions absent from the tow vehicle. Trailer brakes, auxiliary power, reverse-light and lighting circuits must be supplied and wired as required for the trailer. Check the actual pin assignments and electrical installation before connecting.
Pollak 7-blade adapter and tester part-number chart
| Pollak part | Component | Vehicle-side interface | Trailer-side connection |
|---|---|---|---|
| 7WB-143V | 7-blade to 4-flat flexible adapter | 7-blade RV socket | 4-way flat plug |
| 7WB-178PFV | Dual 4-flat / 5-flat adapter | 7-blade vehicle-side connection | 4-way and 5-way flat |
| 7WB-199PDV | 7-blade LED circuit tester | 7-blade vehicle socket | No trailer outlet |
Why the three parts are different
7WB-143V: A flexible-wire adapter between a compatible 7-blade vehicle socket and a 4-flat trailer plug. It is intended for a trailer needing the appropriate four-way lighting connections; it does not add electric-brake controls.
7WB-178PFV: A dual-output 7-blade-to-5/4-flat connection option. It is intended for trailer owners who need 4-way or 5-way flat outputs. Confirm the mating interface and vehicle wiring before treating it as a replacement for an existing socket.
7WB-199PDV: A polarized LED 7-blade socket circuit tester. Its lights help verify socket continuity, but the tester is not an adapter and cannot guarantee correct trailer braking or rule out every fault under load.
Match the Pollak part to your vehicle and trailer
Pollak 7WB-178PFV
Dual 4-flat / 5-flat adapter
Provide separate 4-way and 5-way flat connections from the appropriate vehicle-side 7-blade interface.
View exact Pollak product
Pollak 7WB-199PDV
7-blade LED circuit tester
Use LED indicators to check vehicle-side 7-blade socket circuits; this accessory is not a wiring adapter.
View exact Pollak productBefore towing
Identify the vehicle-side and trailer-side connectors, inspect the socket for corrosion or damage, and confirm all required lamps and safety functions operate after connection. Follow the tow vehicle and trailer manufacturers' wiring diagrams if an electrical fault remains. Keep the connection secure and protect unused contacts from dirt and moisture.
For other connector combinations, see the CURT trailer wiring adapter selection guide.
Common questions
Will a 7-blade-to-4-flat adapter provide trailer brake power?
No. A four-way flat connection does not itself provide the separate electric-brake circuit required by an electric-brake trailer.
Is 7WB-178PFV the same as a simple 4-flat pigtail?
No. It is a dual-output connection design supporting 4-way and 5-way flat trailer connections from a suitable 7-blade vehicle interface.
Does 7WB-199PDV repair a wiring problem?
No. It is a diagnostic tester for the vehicle socket. Any missing or incorrectly connected circuits still need proper troubleshooting and repair.
Quick product links: 7WB-143V · 7WB-178PFV · 7WB-199PDV
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