Hello,

I made a post in the 2017-2022 superduty section, but found another issue, and also found that this forum existed, so figured I'd post here for some help. I bought this truck a month ago, it's a 2022 and whoever owned it before me had a liftgate on the rear end. Everything is good with the truck except for a few plugs that were cut by the spare tire. I assume these were cut because of the lift gate wiring.

My post is here: 2022 f250 6.2 gas, no trailer lights whatsoever

The original problem I had was no trailer lights, which I figured out to be a corroded and broken 7 pin plug directly behind the bumper. Replaced that with a pigtail kit and all trailer-related things work now. Second issue I had was only the driver side back-up sensors were working. I replaced the 6-pin plug (connector C421). Replaced the female side with a pigtail kit and the backup camera and rear sensors work perfectly.

The current problem I have is that my tailgate lock doesn't work. I can open and close the tailgate fine with the latch, it stays shut when closed, but I am unable to lock it. No action at the actuator. Fuses related to BCM and the tailgate release actuator are good and not blown. I do not have the rear light or approach sensor, just the power tailgate lock.

I have four missing plugs (two for the 5th wheel prep harness which I don't have so not worried about them) and 2 right behind the hitch frame. The other plugs/connectors behind the bumper are all clicked in and I've added dielectric grease to them (the two on the passenger side frame rail, the 12 pin plug C4003, the 8 pin plug C421 and the 6 pin plug C4002).

Based on this post (What are these wiring plugs?), I am missing the beige two-wire plug and the black two-wire plug (connector C4223+C4499 or C3137+C3138 I think??), but I only have one side of whatever harness they are from so I suspect that if those plugs had not been cut i would have them capped off on my truck?? Unless I'm wrong. I think the tailgate lock actuator itself is good, but I have no real way of testing it until I figure this out.

EDIT: Would anyone have a photo of what their plug situation looks like under the truck?

 

Looks like you need a grey/brown and a brown/green wire to work the latch. Any wires back there that are those colors?

 

Yeah, I was just going through the wiring diagram as well, thanks for this! I will go down and check to see. From the crappy picture I have though, it looks like I have 1 pair that is green and black and a second pair that is brown and black. I will check again to confirm.

Based on the diagram service manual, C4223 and C4499 show as tailgate release actuator and tailgate release switch. I have the wires off the main harness but no extra plugs or anything off the tailgate harness so these must be for options I don't have? I've seen photos of other trucks with these two plugs capped off. One is a light grey or beige plug and the other is black, both are 2-wire plugs.Example: Post #7 in this thread: https://www.ford-trucks.com/forums/1...ing-plugs.html or this post on tremorforums: https://www.fordtremor.com/threads/p...13/#post-77189

I did take another look at the 12-pin connector (C4003) earlier today and noticed that Pin # 7 (white-brown) is broken on the male side. The broken pin is not stuck in the female side which makes sense because the tailgate would have been removed from the truck when the lift gate was installed. Based on the diagram you posted, C4003 is for the tailgate latch actuator but I haven't figured out yet what Pin #7 is for specifically.

 

If the diagram above is correct, looks like pin 10 and 11 are the latch actuator for the tailgate in C4003.

 

Interesting, thanks for the info. I will go back and test the plug.

Edit: Nevermind, I just figured it out, wire-colours haha. Been a long day, but thanks for the info. If that is correct, I have those two wires in C4003 which means everything is connected correctly. Maybe my actuator is dead.

Out of curiosity, how would I go about figuring out what pin in a connector is for? Like I mentioned in my previous post, Pin # 7 (white-brown) in C4003 is broken, but all I have is the connector and wire colour. I havent found a diagram that shows a white-brown wire and the C4003 connector.

 

If you look hard enough, you may find a connector reference that spells out the wire color AND the circuit function. I do not know what you are using for diagrams, but the Ford DVD would probably have it. I don't have access to anything that new, except my local Chiltons library service.

 

Understood. I'm using the AllData service manual. I just googled C4003 connector + white-brown wire and found this page: https://www.starkey-products.com/pro...tion-2020-2022

Looks like it's for the tailgate light, just need to figure out which diagram that is.

 

I finally found my multimeter so I went out to test the two wires on the C4003 plug - Grey-Brown and Brown-Green. I've got power to the two pins at C4003. I then test the 2-pin power plug in the tailgate at the actuator itself. I've got power to the plug, so it sounds like my actuator is no good. Next step, replace that and see what happens!

 

Sounds like that might be considered a courtesy light. So try looking for it in the courtesy light wiring section. These newer trucks are fun aren't they?

 

`So the new actuator came in and it doesn't work either, so I'm not sure whats up. Possibly a bad ground causing intermittent or weak voltage to the actuator? Gotta find the ground point for the circuit now.

And also no luck finding what pin #7 is on C4003.

Yes, these new trucks are definitely fun

Edit: So here's an interesting update...I cleaned all of the connections behind the bumper, contact cleaner and dielectric grease on all of them, lock still didn't work. Removed and cleaned all of the ground wires in the rear end of the truck, lock still didn't work.
I gave up and moved on to putting in a dust seal around the tailgate and replacing a broken marker light on the driver side mirror that got cracked from a rock off a transport. It was full of water and the top led strip didn't work. Anyways, I replaced the light, put it all back together and put all my tools away, shut the doors, shut the tailgate and locked the truck. By some miracle, the tailgate lock now works!I have no clue what did it, possibly replacing the marker light? Or letting the contact cleaner or dielectric grease work its magic?