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I've searched for a thread with the same problem I'm having and came up empty.
I recently purchased a new livestock trailer that is equipped with LED lights. The lights work as designed and the turn signals flash at the slow steady pace of the truck. Here's the oddity: when the truck is turned off with the key removed, the brake lights will briefly flash about every 8-10 seconds.
All of the threads I found discuss hyper-flashing of the turn signals but that's not what I'm experiencing. Any suggestions on how to cure this problem?
Does the trailer have a break away switch with a small battery to activate the brakes in case of hitch failure? (small cable with a loop on it, little black switch on the goose) That switch could be the culprit. They are kinda cheesy.
Still gotten find a pulsing source. The brake controller does send a pulse searching for a trailer circuit, but I didn't think you could have the pulse with the key off, so the point about one being added or modified is a good one. Those lights will work on such a low current the problem could have been in the truck all along, but never showed up with traditional light bulbs.
Still gotten find a pulsing source. The brake controller does send a pulse searching for a trailer circuit, but I didn't think you could have the pulse with the key off, so the point about one being added or modified is a good one. Those lights will work on such a low current the problem could have been in the truck all along, but never showed up with traditional light bulbs.
What year is the truck?
Steve
If it has an aftermarket controller, they usually work with key off. The other thought was ABS.
Great information in the replies! To recap the questions posed:
Truck is a 2000 XLT, 7.3
No security system
Aftermarket brake controller, Prodigy II - From their product description: "Continual diagnostics check for proper connection, shorted magnet conditions and much more." The unit has LEDs that show connection while the truck is running. They will stay lit for about 10 minutes after the truck is shut down, then they turn off. I assume at that point the unit is longer drawing power from the truck battery since it could kill the battery if the truck sits for an extended time.
The truck is equipped with ABS.
The trailer is equipped with a break-away switch and battery.
Well, unplug the trailer from the truck and see what happens. That will tell you if the flashing is coming from the TBC in the truck or from the on-trailer system.
If it's staying with the trailer, take it back to the dealer for repair - it's brand new and certainly has a warranty.
The break-away on the trailer is an all or none. I doubt it is the trailer.
Here is my thought in line with the brake controller. If the brake controller was wired without using the plug on the truck, something I have seen often, it may be wired to an unswitched source in which case the controller will be sending a pulse signal continuously regardless of the ignition switch.
The pulse voltage is so low, I doubt it would ever flash regular bulbs as that is not a complaint with brake controllers. There just isn't enough voltage there to push enough amps to heat up the element.
I know this is just all conjecture, but I am going with a continuous hot on the black lead to the brake controller, if it is an aftermarket controller.
When the trailer is unplugged from the truck - no flashing.
The Prodigy was wired into the truck's trailer wiring harness under the dash. I'm thinking the next time I get the chance, I'll connect the trailer to the truck and disconnect the hot side of the brake controller to see if the flashing stops. If so, then I will know the flashing is being generated by the Prodigy.
