2014 F250 trailer light problem
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Trailering
Joined: Apr 2017
Posts: 16
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2014 F250 trailer light problem
I have a 2014 F250, 6.7 Crew cab 4x4 shortbed.
The problem is, I have power to the running lights, but no stop or turn signal. I have plugged the truck to three different trailers and came up with the same results. The plug doesn't look to be corroded, I use contact cleaner quite frequently because I am in upstate NY. I checked the fuses in the cab, and they are fine. I even switched a relay in the panel under the hood. I wasn't able to check all the fuses, but I did check one by switching it with another and it showed that it was working. I believe there are two or more fuses related to the lights that I havent had a chance to look at.
I have tested both the 7 &4 pin plugs and both have power to the running lights but that is it. The 7 pin did have power to the + also.
Does the plug have connectors in the wiring harness light the 90's models did, so you could just unconnect and replace the plug, or is it hard wired into the wiring harness.
Any help and suggestions is appreciated.
The problem is, I have power to the running lights, but no stop or turn signal. I have plugged the truck to three different trailers and came up with the same results. The plug doesn't look to be corroded, I use contact cleaner quite frequently because I am in upstate NY. I checked the fuses in the cab, and they are fine. I even switched a relay in the panel under the hood. I wasn't able to check all the fuses, but I did check one by switching it with another and it showed that it was working. I believe there are two or more fuses related to the lights that I havent had a chance to look at.
I have tested both the 7 &4 pin plugs and both have power to the running lights but that is it. The 7 pin did have power to the + also.
Does the plug have connectors in the wiring harness light the 90's models did, so you could just unconnect and replace the plug, or is it hard wired into the wiring harness.
Any help and suggestions is appreciated.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Check fuse F100 in the underhood fuse box.
If/when you check or otherwise fiddle with fuses or relays, tell us WHICH ones you're messing with and report your SPECIFIC observations. We aren't psychic, you know.
If/when you check or otherwise fiddle with fuses or relays, tell us WHICH ones you're messing with and report your SPECIFIC observations. We aren't psychic, you know.
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Trailering
Joined: Apr 2017
Posts: 16
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here is a list of the fuses I checked.
Under the hood fuse/relay box
#26 Trailer tow park lamps 30A
#29 Trailer tow park lamps Relay which I swapped around with the heated mirrors relay
#100 Trailer tow turn signals 25A I popped the cover off and checked for continuity
So how does the 7/4 pin plug connect to the wiring harness? Is it hard wired or is it plug and play?
I don't ever expect anyone to be physic by the way. I am just asking for help.
Under the hood fuse/relay box
#26 Trailer tow park lamps 30A
#29 Trailer tow park lamps Relay which I swapped around with the heated mirrors relay
#100 Trailer tow turn signals 25A I popped the cover off and checked for continuity
So how does the 7/4 pin plug connect to the wiring harness? Is it hard wired or is it plug and play?
I don't ever expect anyone to be physic by the way. I am just asking for help.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Since both sides are not working, you need to focus on whatever is common to both sides unless you think you have two simultaneous failures. None of common components is beyond the battery junction box except ground which is working (running lamps work, same ground circuit).
You need to actually measure the VOLTAGE on both fuse test points to see if the circuit is HOT or not. Even if the fuse checks good, it doesn't mean the circuit has power. If there's no supply power, the lamps will never work.
Why are you messing with them? You said the running/park lamps work on the trailer.
The brake turn circuits are supplied by two individual relays, one for each side. When a turn signal is activated. the corresponding relay is energized to supply power from F100 to the appropriate trailer circuit. When the brake is applied or when the 4-ways are activated, both relays feed power from F100 to both trailer turn/brake circuits.
Check voltage at F100 first.
Turn on each turn signal one at a time, and check if the corresponding relay clicks in time to the signal flashing.
Report results.
#100 Trailer tow turn signals 25A I popped the cover off and checked for continuity
#26 Trailer tow park lamps 30A
#29 Trailer tow park lamps Relay which I swapped around with the heated mirrors relay
#29 Trailer tow park lamps Relay which I swapped around with the heated mirrors relay
The brake turn circuits are supplied by two individual relays, one for each side. When a turn signal is activated. the corresponding relay is energized to supply power from F100 to the appropriate trailer circuit. When the brake is applied or when the 4-ways are activated, both relays feed power from F100 to both trailer turn/brake circuits.
Check voltage at F100 first.
Turn on each turn signal one at a time, and check if the corresponding relay clicks in time to the signal flashing.
Report results.
New User
Joined: Jul 2017
Posts: 3
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I'm having a similar problem with my 2014 F250's 7 way and 4 way flat. In my case I have no continuity to any portion of the 7 way or 4 way. All fuses and relays have been replaced and still no power to trailer lights. Any ideas before I drop it off at Ford. Thanks in advance
New User
Joined: Jul 2017
Posts: 3
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7 way pin
Yes, And went ahead and replaced just to make sure and still nothing. I'm guessing that one of our trailers may have had a short and caused some of the wires to burn up in the harness. Went to Ford dealer today and they could not help.
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FTE Legend
Joined: Jul 2005
Posts: 65,938
Likes: 1,432
From: Millersville, MD
Ohm out those wires for continuity... or use a 12v probe to see if you have voltage - and where you lose it. All RV'ers should have one of those cheap 12v probes. Much better than a volt meter.
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New User
Joined: Jul 2017
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Thanks I'll pick one up and see if I can find the problem.
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