Morning.
I am having issues with my 2017 f250 regarding multiple electrical malfunctions happening at once. It started with a cross-traffic control module malf. then a blind spot malfunction, leading to no radio control on the console except on the steering wheel, and no ac control. It blows but only cabin air temp, daytime lights flicker, no blinkers, front windows won't roll down, back windows will, and cannot fold in mirrors all while the truck is running. Once the truck is off and the key is turned forward to the electrical-only position. everything works until the faults catch up.
noticed that someone had cracked my rear left taillight and there was some standing water in the bottom of the light.
trouble-shooting:
removed the taillight and drained the water. checked all lights. dried out the housing. checked cross traffic control module of wear and tear. all lights work.
checked aft wiring harness. coupling was dry. applied grease around the connection and refit. no change.
disconnected batteries and refit terminals. no change.
checked all fuses on BCM. none are blown. refit all fuses and no change.

I am at a loss right now.

 

Very common. There is a plug up near the spare tire. Known for water intrusion and the many gremlins that you note. I had this happen with a 2017 that was only a few months old. Caused problems with driver side window, HVAC controls, radio controls and trailer indicator warnings among other things I've forgotten by now. Dealer replaced under warranty and problems all went away.
You mentioned aft wiring harness but I'm not sure which you mean. Some people think it's at the trailer plug connection.
Find the plug, dry it out and it there isn't too much corrosion put it back together with dielectric grease. If it's badly corroded it will probably need replacing.

 

 

You post that same pic every time. And it's always helpful. Especially since I don't have any pics on hand to show other folks and I don't feel like crawling under the truck to get one!

 

Yeah already pulled it apart. Cleaned it and resealed it. Still having issues

 

How about the back side of the 7 pin trailer plug?

 

Make sure the lid is still on your battery junction box. It can have water run down onto/into it and will cause all kinds of weird electrical issues, until it finally dies. There was a TSB on the 2020s so I don't know if it also be on earlier years or not. But it is easy enough to check to make sure the lid is secure.

bob

 

Start checking ground points throughout the truck, even ground cables. Had one corrode internally so no visual hint, but an ohm meter discovered it on my Bronco.

 

so i repulled the driver side tail light. took out the blind spot radar module. unhooked the cannon plug and boom, tons of water came out. got the air compressor on it and blew all the water out on both the male and female ends. reseated the plug and immediately still had the issue. gave up for a bit. came back out started the truck, no faults. recycled the ignition about 4 times, no faults. started the truck and ran it up to the store and back, total time about 15 minutes. no faults. came back and sealed the crack on the light that runs the length of the radar box with some clear silicone caulk. waterproof in 40 minutes. until i can find a cheaper tail light less than a grand this will have to work....hopefully.

 

It's a pic I took under my truck so it's on my computer, only takes a second to post. I could have been a hand model...

 

Well done hopefully you have found the culprit to your gremlins. Electrical troubleshooting can be tough good to hear it is most likely resolved. Double check that under hood fuse box lid to be sure it is closed tight. Happen to find that issue on my own when I open my hood just after it rained and noticed the lid was soaked after water ran off the back of the hood and onto that fuse panel cover. What a mess that can be if that cover is not installed correctly or cracked.

Mike

 

still having issues today. motherful;aksdgnvl;iasdhjfaxcER!!!!!!!!!!! i was about to pull the plug and buy a new set of lights for around 3K. stupid i know. however I said one last check wont hurt. Repulled the damn light and completely dismantled it this time. Took the bulbs out. took the BLIS housing out. Disconnected it and checked for water. nope. no corrosion either. then actually checked the cannon plug that goes in to the radar itself. HOLY **** BATMAN. blue green corrosion all over the prongs and tons of water cam shooting out. got the air compressor out again. blew it out and dried it. took the copper wire brush to it and scrubs the best i could without damaging it. Then got some qtips and rubbing alcohol and cleaned the ever loving **** out of it. let sit for 10 minutes. reconnected. zero issues. turned it off and started it again and left running for 15 minutes. no issues. could this be it. did i just save myself 3k. man i hope so. gonna run a few more tests again and see. but it will probably act back up in the morning. Thanks to all you that helped out with this. good to know all of the areas this one issues could stem from.

AJ

 

Never used it myself but have seen guys use it on automotive connectors successfully before they were too far gone, like rotting away would be too late obviously.

 

I’ve used Deoxit op at work and on aircraft connectors.

Another product I keep in my rv and at home is Corrosion-X. I’ve had it restore intermittent aircraft Push to Talk switches and even an outdoor light switch on my barn.
Ford has an approved product called XG-12. That’s what I would use on new truck contacts/connectors.