Should I Be Able to Hear Trailer Brakes Hum Constantly with Manual Override Engaged

Question:

Good afternoon, I have a 2017 Montana 3710FL and 2022 GMC Sierra Denali 3500. I have replaced all my electric drum brakes with exact e-trailer replacements, both the full backing plate and drum. I have 13v constant at the truck 7pin, and 12.4v at my drum brakes. I have inspected and cleaned my ground connection at the trailer and checked the main wire run from 7 pin to the first split at the front axle and show .25 ohms resistance. When I manually trigger the brake controller gain in the truck to 100, the brakes hum for about 3 seconds then stop. My question is, shouldnt they hum the entire time theyre engaged? If they are supposed to stay humming, where do I look next?? Thank you in advance

asked by: Ryan N

Helpful Expert Reply:

Thanks for your continued support, Ryan!

While it's normal to be able to hear electric brake drums, like your Dexter Nev-R-Adjust Electric Trailer Brake Assembly # 23-464, humming when power is being applied to them, I recommend trying to physically move your trailer tires before investigating every inch of your wiring and magnets (which would be the next step).

Sometimes the magnets can be a little quiet so what I recommend doing is lifting your trailer up by the frame enough for the tires to be off the ground, and then having someone else use and hold the manual override while you try spinning the tires by hand. If you aren't able to do so then it sounds like the brakes are working just fine and you can do a "pull" test with your truck and trailer to make sure the trailer brakes stay locked up with a larger force pulling on it.

If you ARE able to spin the tires by hand then you need to either adjust their strength or you need to check out the linked article on testing brake magnets to narrow down whether the issue is with the brakes or the wiring on your trailer.

expert reply by: Jon G