No power at 7-way plugUpdated 3 days ago

This article assumes that you've previously tested your trailer's 7-way plug and found that there is no voltage (or insufficient voltage) available on the  "AUX 12 Volt + (Black)" pin, as shown in the diagram below.

In trailers with DC-DC chargers installed, this pin may not be able to supply power from the trailer batteries.

IF:

• there is no power detected at the 7-way plug, AND
• the trailer does not have a DC-DC charger installed, AND
• the original factory wiring for the trailer's 7-way plug has not been altered

THEN: It is possible that the breaker for the 7-way plug has failed.

.SAMPLE schematic from a late-model Airstream trailer. Your trailer schematic may vary; see your Owner's Manual.

In many late model Airstream trailers, the AUX 12V+ pin from the 7-way is connected to a self-resetting breaker. If this breaker fails, there will be no connection between the 7-way plug and the trailer batteries. In this case, other symptoms would include:

• trailer batteries do not charge from the truck during towing. (However, they might charge from rooftop solar panels.)
• AIR GEAR Portable Solar Kit charge controller will not turn on when connected to the 7-way plug.
• AIR GEAR MiniLink will not supply power.

Resolution

If failed, this breaker can be replaced by a qualified technician. Be sure to match the exact type and amperage rating of the original breaker.

Example of resettable DC breakers

Note that the schematic and photo above are only representative. The wiring schematic and appearance of the breakers on your trailer may vary from what's shown here.

AIR GEAR cannot provide assistance with diagnosing a power problem in your trailer or motorhome. A failed breaker can be a sign of a more serious electrical problem, so please contact a competent RV technician.