Topic Sponsor
2015 - Present Ford F150 General discussion on the latest generation Ford F150 truck.
Sponsored by:
Sponsored by:

Tailgate locks but won't unlock

 
Old 08-14-2018, 12:18 AM
  #1  
Member
Thread Starter
 
Join Date: Apr 2018
Posts: 31
Received 4 Likes on 4 Posts
Default Tailgate locks but won't unlock

I bought a used 2015 F150 Screw and the tailgate lock won't work.

I've since replaced the tailgate actuator with no luck. Thinking that its an electrical / ground issue I found that when I grounded the ground (see pic) wire that it locks but won't unlock. So now its stuck in the lock position.



New tailgate actuator.


Anyone else have any ideas on what I can try next? My next guess that the hotwire sends a different amount of power for unlock or lock so I might try and tap into an unlock / lock wire closer to the cab.

Thanks!
SRos1015 is offline  
Old 08-14-2018, 12:03 PM
  #2  
Senior Member
 
Gordy49913's Avatar
 
Join Date: Oct 2016
Location: Chicago area
Posts: 1,224
Received 216 Likes on 195 Posts
Default

Originally Posted by SRos1015 View Post
I bought a used 2015 F150 Screw and the tailgate lock won't work.

I've since replaced the tailgate actuator with no luck. Thinking that its an electrical / ground issue I found that when I grounded the ground (see pic) wire that it locks but won't unlock. So now its stuck in the lock position.



New tailgate actuator.


Anyone else have any ideas on what I can try next? My next guess that the hotwire sends a different amount of power for unlock or lock so I might try and tap into an unlock / lock wire closer to the cab.

Thanks!
Looking at the wiring diagram, the polarity of the two wires gets reversed. So remove your ground wire, you have an open in one of those wires. I can't tell which wire you have connected to ground. If you hit the lock button the gray/brown is hot, the brown/green wire is ground, when you unlock its the opposite. Did you check the plug right under the bumper? The other end is under the hood of the truck on top of the drivers side fender wheel. Pin 1 would be the brown/green and pin 34 is the gray/brown.
Gordy49913 is online now  
The following users liked this post:
SRos1015 (08-14-2018)
Old 08-14-2018, 12:14 PM
  #3  
Senior Member
 
Join Date: May 2016
Location: Seattle, WA
Posts: 449
Received 78 Likes on 59 Posts
Default

If I recall correctly, polarity is reversed to unlock the tailgate.

(Also note this a security vulnerability with the trucks, I could easily make a device that plugs into the tailgate connector to unlock the tailgate and get access to the bed of these vehicles).
KG7BTU is offline  
The following users liked this post:
SRos1015 (08-14-2018)
Old 08-14-2018, 12:14 PM
  #4  
Member
Thread Starter
 
Join Date: Apr 2018
Posts: 31
Received 4 Likes on 4 Posts
Default

Originally Posted by Gordy49913 View Post
Looking at the wiring diagram, the polarity of the two wires gets reversed. So remove your ground wire, you have an open in one of those wires. I can't tell which wire you have connected to ground. If you hit the lock button the gray/brown is hot, the brown/green wire is ground, when you unlock its the opposite. Did you check the plug right under the bumper? The other end is under the hood of the truck on top of the drivers side fender wheel. Pin 1 would be the brown/green and pin 34 is the gray/brown.
I did check the plug right under the bumper and everything looks ok. I'll remove the ground wire and take a look at the driver side fender wheel. Thanks for the input! I'll report my findings asap.
SRos1015 is offline  
Old 08-14-2018, 12:20 PM
  #5  
Member
Thread Starter
 
Join Date: Apr 2018
Posts: 31
Received 4 Likes on 4 Posts
Default

Originally Posted by KG7BTU View Post
If I recall correctly, polarity is reversed to unlock the tailgate.

(Also note this a security vulnerability with the trucks, I could easily make a device that plugs into the tailgate connector to unlock the tailgate and get access to the bed of these vehicles).
Thats why I couldn't get a good read with my multimeter... that explains why I could get a read on either lock or unlock but not the other way... Thanks!

SRos1015 is offline  
Old 08-14-2018, 02:08 PM
  #6  
Senior Member
 
Gordy49913's Avatar
 
Join Date: Oct 2016
Location: Chicago area
Posts: 1,224
Received 216 Likes on 195 Posts
Default

Originally Posted by SRos1015 View Post
I did check the plug right under the bumper and everything looks ok. I'll remove the ground wire and take a look at the driver side fender wheel. Thanks for the input! I'll report my findings asap.
I would test underneath the truck, the wire maybe open going up to the tailgate. One lead to ground and test each wire first, then at least you know which way to go.

If someone is breaking in, doesn't make a difference how its locked, they will get in.
Gordy49913 is online now  
The following users liked this post:
SRos1015 (08-14-2018)
Old 08-14-2018, 07:22 PM
  #7  
Member
Thread Starter
 
Join Date: Apr 2018
Posts: 31
Received 4 Likes on 4 Posts
Default

Found the issue thanks to Gordy49913s recommendation on checking under the hood. The harness in the pic below wasn't on snug enough and it didn't lock together as it should since one of the plastic pieces was off the hinge. A quick 5 minute fix and everything worked on the tailgate including the backup lights. Thanks everyone!



Driver side electrical harnesses.
SRos1015 is offline  
The following users liked this post:
Gordy49913 (08-14-2018)
Old 08-14-2018, 07:52 PM
  #8  
Senior Member
 
Gordy49913's Avatar
 
Join Date: Oct 2016
Location: Chicago area
Posts: 1,224
Received 216 Likes on 195 Posts
Default

Originally Posted by SRos1015 View Post
Found the issue thanks to Gordy49913s recommendation on checking under the hood. The harness in the pic below wasn't on snug enough and it didn't lock together as it should since one of the plastic pieces was off the hinge. A quick 5 minute fix and everything worked on the tailgate including the backup lights. Thanks everyone!



Driver side electrical harnesses.
Thanks for letting anyone that reads this.
Gordy49913 is online now  
 


Thread Tools
Search this Thread
Quick Reply: Tailgate locks but won't unlock


Contact Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: