Troubleshooting A Tekonsha Sentinel Brake Controller That Keeps Flashing

Updated 08/01/2025 | Published 08/25/2023

Question:

I have a 1996 Tekonsha Sentinel break controler mounted in my 1986 250 Ford pickup. I have used it and it worked fine. I havent used my pickup for years towing anything. Inotice that my controller light blinks all the time. Is this suposed to blink all the time even when the ignition is turned off. It has been so long since I have used it ,I dont remember how to use it? I am 92 years old. Please help.

asked by: V L

Expert Reply:

If the lights are flashing on your Tekonsha Sentinel brake controller it's most likely going to be a short in the wire, a bad ground connection or poor voltage from the vehicle's battery. You'll want to check the voltage with a multimeter # PT89ZR at the brake controller to ensure it's actually getting 12 volts. Next you can check the ground connection to make sure it isn't loose or corroded. You can also trace the wires to check for any kinks, cuts, or damage that could cause a short. If all of this is fine then the unit itself is most likely just faulty at this point and would need to be replaced.

expert reply by: Kevin C

Chris G.

7/31/2025

i have a Tekonsha Sentinel Brake Controller, when the trailer is hooked up, i step on the truck brake pedal the light on the right side of the controller flashes once, and nothing happenes (brakes do not engage) when i move the slider under the controller all the lights come on as they should and the trailer brakes engage.

Jesse M.

7/31/2025

@ChrisG Are you testing this with the vehicle parked? If so, that is normal. The Sentinel brake controller is activated by inertia. So it will only apply the trailer brakes via the brake pedal when it detects deceleration. The manual slide will work anytime, even when parked. The brake pedal only activates the brakes when you are decelerating.

Chris G.

7/31/2025

@JesseM i am just testing by feel when the vehicle is moving.

Jesse M.

7/31/2025

@ChrisG How fast were you going? Sometimes it takes a bit of speed to get the accelerometer to activate but it should work even at low speeds. If the light flashes once then nothing else happens this is an indication that there is an issue such as a short or excessive current on the system or low battery on the tow vehicle