trailor light trouble
Thread Starter
|
Senior User
Joined: Aug 2008
Posts: 124
Likes: 0
From: Tuscumbia , Al
trailor light trouble
2004 F350 6.0 Diesel 2WD, Question is my trailor lights running lights work fine also the electric brake, but i have no stop or right or left turn signals the truck signals are all working perfect. The truck came with factory wiring i have checked it at the plug on bumper with meter to make sure it was not the trailor. Looked for blown fuses and cant find anything what am i missing it should have seperate fuses for trailor lights ?? 
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
There is a separate fuse and relay for all the trailer circuits. The turn/stop lights is fuse #6 under the dash. Be sure to check it with a test light or meter. It is possible for a fuse to be bad but not appear blown.
2nd Gear
Joined: Sep 2011
Posts: 2
Likes: 0
2004 F350 6.0 Diesel 2WD, Question is my trailor lights running lights work fine also the electric brake, but i have no stop or right or left turn signals the truck signals are all working perfect. The truck came with factory wiring i have checked it at the plug on bumper with meter to make sure it was not the trailor. Looked for blown fuses and cant find anything what am i missing it should have seperate fuses for trailor lights ??
Thread Starter
|
Senior User
Joined: Aug 2008
Posts: 124
Likes: 0
From: Tuscumbia , Al
Tried it first and it was good
Thread Starter
|
Senior User
Joined: Aug 2008
Posts: 124
Likes: 0
From: Tuscumbia , Al
Yes mine does have this there is only 1 fuse and it was good but there are 4 relays. But the owners manual has no info on any of it
Senior User
Joined: Feb 2011
Posts: 343
Likes: 0
From: maine
Just a thought but have you checked the bulbs? Next I would check the grounds on the trailer fixtures.
Trending Topics
Thread Starter
|
Senior User
Joined: Aug 2008
Posts: 124
Likes: 0
From: Tuscumbia , Al
All on truck work fine. And have tested at both connectors on bumper with meter they are dead at this point only constant 12volt and running lights and electric brake are working
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Junior User
Joined: May 2011
Posts: 63
Likes: 7
From: NW PA
Stop lights and turn signal light the same filament in the bulb. It's weird both bulbs would be bad but after you check them put a tester on that contact in the trailor light housing. If there is power there like said before it might be the ground. Make sure the trailer has a ground, don't count on the ball to give you a good ground. I just spent a full day fixing the wiring on a used trailer I just bought. The PO actually had the bulbs in the trailer sockets backwards, go figure 
Thread Starter
|
Senior User
Joined: Aug 2008
Posts: 124
Likes: 0
From: Tuscumbia , Al
Stop lights and turn signal light the same filament in the bulb. It's weird both bulbs would be bad but after you check them put a tester on that contact in the trailor light housing. If there is power there like said before it might be the ground. Make sure the trailer has a ground, don't count on the ball to give you a good ground. I just spent a full day fixing the wiring on a used trailer I just bought. The PO actually had the bulbs in the trailer sockets backwards, go figure
Freshman User
Joined: Oct 2011
Posts: 31
Likes: 0
Your 2004 f350 should have a trailer accessory box under the hood (actually there are two). One contains the reverse relay and fuse that runs off the Transmission shift position signal to drive the relay which supplies the trailer reverse light. The other box has two relays and a fuse in it to control Left and Right signal/brake lights. It gets control of the relays from the left and right turn signal wiring (coming from the steering column multifunction switch) and supplies the trailer wiring from there.
Personally, I find the way ford has done this to be rediculous but we have to deal with what they dump on us.
Personally, I find the way ford has done this to be rediculous but we have to deal with what they dump on us.
Senior User
Joined: Feb 2011
Posts: 343
Likes: 0
From: maine
I agree with this post after ripping off my plug under the bumper, I drilled and mounted new plug in the bumper. The 3rd time I hard wired the new 7 round plug with shrink connectorsand I bought a 4 plug adapter (which is in my door pocket unused) Stab the wire before the factory plug under your bumper. I have an '04, too, been awhile but when I saw the quoted post I had a flashback, lol
New User
Joined: Mar 2015
Posts: 4
Likes: 0
I have a 2004 PSD crew cab, and just like the original poster, running lights but no turn/brake lights for either side on the trailer. Truck works just fine.
Tried reading voltage across fuse 6 but not getting anything, yet when I pull the fuse and stick the meter in I get a reading. I have 3 relay/fuse boxes under the hood, not sure which of them is the trailer turns. Ford has tested the wiring from the back going forward, but stopped before getting into the fender area as it was just too much of an unknown and I'm not paying them to go fishing!
I have checked voltage at the 7 wire plug on bumper also, I'm only getting really low numbers there. Not sure if that makes it easier to pin point where the issue is if it's just crappy relays or just a grounding issue.
If anybody has an idea of where I could look some more, or maybe direct me as to which of the little black boxes I could check it would be greatly appreciated. Previous owner hauled with the truck lots, but did say there was always an issue with lights, yet I have never had them working yet.
Tried reading voltage across fuse 6 but not getting anything, yet when I pull the fuse and stick the meter in I get a reading. I have 3 relay/fuse boxes under the hood, not sure which of them is the trailer turns. Ford has tested the wiring from the back going forward, but stopped before getting into the fender area as it was just too much of an unknown and I'm not paying them to go fishing!
I have checked voltage at the 7 wire plug on bumper also, I'm only getting really low numbers there. Not sure if that makes it easier to pin point where the issue is if it's just crappy relays or just a grounding issue.
If anybody has an idea of where I could look some more, or maybe direct me as to which of the little black boxes I could check it would be greatly appreciated. Previous owner hauled with the truck lots, but did say there was always an issue with lights, yet I have never had them working yet.
Last edited by Ford89mustang; Mar 28, 2015 at 11:17 AM. Reason: Missing info
