Ford Truck Enthusiasts Forums

Notices
2017 - 2022 Super Duty The 2017-2022 Ford F250, F350, F450, F550 & F600 Super Duty Pickup and Chassis Cab
Sponsored by:
Sponsored by: CARiD

electrical problem

   
Old Aug 19, 2019 | 12:15 PM
Share
  #1  
pdarby's Avatar
pdarby
Thread Starter
|
New User
Joined: Nov 2013
Posts: 20
Likes: 0
electrical problem
I have a 2017 F350KR DRW 4x4. When I test the trailer 7 way plug with a 7way tester I get no light in the 12V position, which I assume means the truck is not charging the trailer batteries. Second when I apply the brakes all I get on the tester is a very dim flickering light on the BK position. Ive checked the fuses and they seem good, don't know how to check the relays though
 
Reply
0
Old Aug 19, 2019 | 12:17 PM
Share
  #2  
HRTKD's Avatar
HRTKD
Hotshot
10 Year Member
Liked
Loved
Community Favorite
Joined: Oct 2015
Posts: 19,694
Likes: 12,819
From: Wyoming
Club FTE Gold Member
On my 2017, all I had to do was press the brakes and I had power to the trailer. Others have reported that more was needed, like closing the driver door and putting it in gear.
 
Reply
0
Old Aug 19, 2019 | 12:26 PM
Share
  #3  
ford390gashog's Avatar
ford390gashog
Fleet Owner
20 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Club FTE Gold Member
The 12v is only hot when the truck is running, the brake wire will only go hot with a trailer connected as the smart trailer tow junction box needs to see the resistance of the trailer.
 
Reply
0
Old Aug 19, 2019 | 12:32 PM
Share
  #4  
pdarby's Avatar
pdarby
Thread Starter
|
New User
Joined: Nov 2013
Posts: 20
Likes: 0
does that mean the brake wire will not go hot with the tester plugged in?
 
Reply
0
Old Aug 19, 2019 | 04:51 PM
Share
  #5  
2019er's Avatar
2019er
Laughing Gas
5 Year Member
Photogenic
Photoriffic
Liked
Joined: Oct 2018
Posts: 767
Likes: 78
From: NC
Saw on another thread here just a few minutes ago, was happening if you enabled police mode through Forscan. Does that apply to your case?
 
Reply
0
Old Aug 19, 2019 | 11:16 PM
Share
  #6  
bobv60's Avatar
bobv60
Fleet Mechanic
Joined: May 2011
Posts: 1,866
Likes: 84
From: Rainier OR
This has happened to others, the tester will not work correctly on the newer trucks.
You wont get power to the B+ untill the brakes are pressed and the truck is moving.
Same with the trailer brakes. Needs to sence there is a load before they come on.
 
Reply
0
Old Aug 19, 2019 | 11:27 PM
Share
  #7  
HRTKD's Avatar
HRTKD
Hotshot
10 Year Member
Liked
Loved
Community Favorite
Joined: Oct 2015
Posts: 19,694
Likes: 12,819
From: Wyoming
Club FTE Gold Member
In my test, the truck did not have to be moving to send 12v power to the trailer. Transmission in Park, engine on, press brake = 12v power to the trailer.
 
Reply
0

Trending Topics

Old Aug 19, 2019 | 11:32 PM
Share
  #8  
bobv60's Avatar
bobv60
Fleet Mechanic
Joined: May 2011
Posts: 1,866
Likes: 84
From: Rainier OR
Originally Posted by HRTKD
In my test, the truck did not have to be moving to send 12v power to the trailer. Transmission in Park, engine on, press brake = 12v power to the trailer.
Thre does seem to be different results from different people. I am thinking that the keyless ignition trucks work differently that the keyed ignition. Might be other options too.
When I tested mine I got nothing till I started driving.
 
Reply
0
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
story-1

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-2

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-3

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-4

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-5

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-6

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-7

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-8

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-9

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
Old Aug 19, 2019 | 11:38 PM
Share
  #9  
HRTKD's Avatar
HRTKD
Hotshot
10 Year Member
Liked
Loved
Community Favorite
Joined: Oct 2015
Posts: 19,694
Likes: 12,819
From: Wyoming
Club FTE Gold Member
Originally Posted by bobv60
Thre does seem to be different results from different people. I am thinking that the keyless ignition trucks work differently that the keyed ignition. Might be other options too.
When I tested mine I got nothing till I started driving.
I was going add almost the same comment. It's very strange that it works differently for so many trucks.
 
Reply
0
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Trailer brakes
kbf1961
1999 - 2016 Super Duty
7
Apr 21, 2012 09:37 AM
Trailer Braking Issue
lawnspecialties
1999 - 2016 Super Duty
11
Jun 23, 2011 08:07 PM
tow command problem
richsoucie
1999 - 2016 Super Duty
16
Aug 29, 2008 02:20 PM
trailer's brakes not working correctly
BobbyDiesel71
All Things Towing
7
Sep 13, 2006 09:02 AM
Back to Subforum
2017 - 2022 Super Duty
View Next Unread
WeatherTech Flaps and New Fastway Hitch


Thread Tools
Search this Thread
Search this Thread:

Advanced Search

Advanced Search
Reply Closed Thread Share
Forum Jump

All times are GMT -5. The time now is 11:45 PM.

story-0
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-05-30 18:33:59


VIEW MORE
story-1
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-2
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-3
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-4
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-5
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-6
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-7
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-8
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-9
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE