Apparent Malfunction of Tekonsha Sentinel Trailer Brake Controller

Updated 12/26/2014 | Published 12/25/2014

Question:

This unit was installed in my GMC 1999 3500 dually pickup when I purchased the truck about two years ago. More recently I purchased a 25/0 fifth-wheel travel trailer, and made one trip with it last September. This trip was about 1000 miles long, and was mechanically uneventful. The trailer has sat dorment from early October through mid-December, at which time I set forth from Shenandoah County, Virginia via I-81 to I-77, heading to Charlotte and beyond. BUT, I noticed at a rest area that the axles serving all four trailer wheels were HOT NOT WARM to the touch, and thus drove another 5 miles to the nearest Camping World, which is closed today. I also noticed that the referenced unit, which usually displayed a solid green light which went to red whenever the brake was applied was then and is still solid red. I am parked at a Camping World outlet waiting for them to open for business Friday. In the meantime,it seems that the brake shoes are continuously under pressure?? The red light remains on, even though the connection between the truck and the trailer has been disconnected. I have no manual for the operation of this unit, only the direction of the mechanic who works for the sales organization. Any advice you may be able to offer will be most certainly appreciated. Thank you, and Merry Christmas.

asked by: Tom C

Expert Reply:

According to my contact at Tekonsha if the green light on your older (and discontinued) Sentinel trailer brake controller is flashing at approximately an 8 second interval, this is a diagnostic light that is showing that the trailer is connected and the system is operating. If the red light is illuminated that indicates that there is current flow to the trailer. When the green light is a solid green light then it is indicating that braking has begun.

Since your red indicator light remains on even with the trailer disconnected from the truck's wiring it could be that the Sentinel has finally failed. This problem could also be caused by corrosion inside your trailer socket at the back of the truck. Severe corrosion could cause two circuits to become bridged together, such as your brake circuit and your trailer 12V power circuit. If this happened the 12V feed could be sent continuously to the trailer's brake circuit which would cause them to remain engaged. This could cause the heat build-up you noticed. Also check the trailer-side plug for the same issue. Clean or replace the connectors as necessary.

Another possibility is that your trailer bearings are low on grease and this is causing the heat. I suggest you remove the hubs and inspect the bearings for signs of heat damage. Make sure the hubs and bearings are fully packed with grease. If they are okay the odds are there is an issue in the wiring or the controller needs to be replaced. If you do need a new controller I suggest the P2 # 90885 which is among the most popular and reliable units we offer.

The linked article on troubleshooting brake controllers may also help out.

expert reply by: Adam R