Incessant beeping while towing with F150
[I put this message on the Ford F150forum.net and have had some response, but nothing that solved the puzzle, hence my posting here]
I bought my 2016 F150 Lariat in January (49,000 miles) to tow my FC 27FB (5,800 lb dry weight). It has the 3.5 Ecoboost, 3.55 axel ratio, and the max tow package. The PO had never towed anything, by the look of the hitch receiver. The two times I have towed the trailer for more than 10 miles two different unexplained beeping/alarms have sounded.
The first time it was after 1.5 hours at moderate highway speeds (55-60 mph). It came from the dash, a triple beep that repeated five times. Occasionally another longer alarm sound (like an old Braun electronic travel alarms with the continuous beeping). No warning lights or any designation appeared on the dash or the console. It repeated every one to three minutes for more than an hour, then stopped. I called a mechanic buddy and asked him if he had any experience with these sounds; he had not. I thought it might have been relaying a weather alert from my iPhone, so I turned off all weather alerts and, coincidently, the sounds stopped. However, on the return trip from the campout five days later, the beeping began almost immediately when I turned onto the highway and continued for four hours, the entire trip.
I searched the manual. I turned off all alerts. Shut down the phone. Called Ford and tried to get an answer. They searched the manual. No dice. Even after I turned off the engine it continued until I exited and locked the door. The truck was in tow mode for this trip. The sound occurred, as noted, whether or not it was in drive. It continued after I shut off the engine until I locked the TV. In travel without a trailer no beeping occurred. All gauges read normal. Tire pressure at 35 psi. I was using premium fuel, as recommended.
Has anyone else experienced this beeping? What might the cause be?