Andy L Posted February 14, 2019 Share Posted February 14, 2019 Does anyone know how the 2018 and newer Expeditions and Navigators detect that a trailer is hooked up? I assume it is something in the trailer wiring connector. I wanted to understand this because I would like for the vehicle to detect the trailer is disconnected after I back into my garage before I shut the engine off. I hope to push a button that will make the vehicle think I disconnected the trailer. That will be better for me than leaving the engine on and pulling the wiring connector or remembering to tell the vehicle that the trailer is disconnected after restarting it (I am not even sure how to do this). Quote Link to comment Share on other sites More sharing options...
akirby Posted February 14, 2019 Share Posted February 14, 2019 The better question is why do you think you need to do this? Maybe there is a better solution to the problem. Quote Link to comment Share on other sites More sharing options...
akirby Posted February 14, 2019 Share Posted February 14, 2019 If you do need to do it here is some info: https://www.f150forum.com/f118/trailer-detection-just-facts-408246/index2/ Quote Link to comment Share on other sites More sharing options...
Andy L Posted February 14, 2019 Author Share Posted February 14, 2019 Thanks Allen. I understand the Expedition/Navigator detects when a trailer is plugged in. However, if you unplug the trailer wiring while the vehicle is turned off, the vehicle will not recognize that the trailer is disconnected. Is that correct? I was trying to push a button on the dash to electrically disconnect the trailer to turn trailer tow mode off before shutting the engine off. I did not see which wire is the detection wire on the link above. Quote Link to comment Share on other sites More sharing options...
akirby Posted February 15, 2019 Share Posted February 15, 2019 But it should detect that the trailer is no longer connected when you start it back up. Why do you think you need to turn off trailer tow mode before shutting the engine off? It defaults to off when you restart the vehicle. There is no “detection wire” per se - it senses current or resistance through one or more of the wires. Quote Link to comment Share on other sites More sharing options...
bcparker2 Posted February 15, 2019 Share Posted February 15, 2019 If you have the tbc you can pinch the tabs quickly a couple times and it should search for the trailer and recognize it being disconnected Quote Link to comment Share on other sites More sharing options...
Andy L Posted February 15, 2019 Author Share Posted February 15, 2019 Thanks. Sounds like I don't need to do anything. I do need to change the reverse wire in the trailer connector. I need to put it on a switch so power is applied to trigger a solenoid to disable the trailer surge brakes (stopping and switching into reverse enables the solenoid too late after the brakes are applied from stopping). Anyone know if there is a good place to intercept this wire? Quote Link to comment Share on other sites More sharing options...
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