Brake Controller Trailer Disconnect Warning Light

Updated 01/28/2020 | Published 01/27/2020

Products Featured in This Question

Replacement Magnet Kit for 12" Electric Trailer Brake Assemblies - 5,200 lbs to 7,000 lbs

(154)

$26.82

Dielectric Grease for Electrical Connectors, 2 oz.

(1481)

$10.96

Question:

I just took my travel trailer in to get bearings packed and new tires put on. Prior to this i have never had an issue with the trailer brakes, they worked great. On my way home from the shop, i noticed the trailer brakes were barely working. I figured they got grease on the pads or something. Also, now my truck brake controller is giving me a warning trailer brake light that comes off and on constantly when towing. It says the trailer is disconnected and then says it is connected. It does this every 20 seconds or so. I know the grease on the brakes will definitely affect stopping, but will it also give me the warning that my controller is telling me? Thanks

asked by: Rudy

Helpful Expert Reply:

An often seen cause for the trailer brake controller to display a disconnect error message is a damaged or corroded connector on the trailer. This may have occurred during it's time at the shop or just didn't show up as a issue until after this work was done.

Other common causes for this error message are a bad connection at the electric brake assemblies or a short on one of the magnets. There could also be damage or a short on the wire that carries the brake circuit. I recommend re-checking the trailer.

Corrosion can occur inside a connector too so you'll want to re-inspect both the external contacts and the back/inside of the connectors if possible for signs of any corrosion. Even slight greenish or whitish discoloration can indicate a corrosion issue, and certainly it can also happen that there can be severe corrosive build-up inside the connectors. Use a product like Dielectric Grease for Electrical Connectors # 11755 to help prevent corrosion.

There is a chance that your trailer connector could be wired differently than your truck since the trailer is new. You can test the trailer by keeping it disconnected from the truck and applying 12V power directly to the brake circuit contact. On a trailer plug this will be the pin indicated by the arrow shown in the linked photo. If the brake circuit activates then it is wired correctly.

A troubleshooting article is linked for you.

expert reply by: Patrick R