Trailer wiring

[Jonneyo]

I’m looking for help replacing the truck wiring for the trailer lights. I’ve had different trailers blow the same fuse when towing. I will replace the fuse and the lights work but after driving the fuse eventually blows and the lights go out. So the problem is somewhere on the truck and not the trailer. I think there must be a worn wire in the circuit that gets grounded while driving. Any help or advise is definitely appreciated.
It’s a 2010 Expedition XLT 4WD

 

[07navi]

Those wires on the trailer have to match the ones in the connector, you need to spend some time with a multimeter and test light to get it right.

 

[Yupster Dog]

I’m looking for help replacing the truck wiring for the trailer lights. I’ve had different trailers blow the same fuse when towing. I will replace the fuse and the lights work but after driving the fuse eventually blows and the lights go out. So the problem is somewhere on the truck and not the trailer. I think there must be a worn wire in the circuit that gets grounded while driving. Any help or advise is definitely appreciated.
It’s a 2010 Expedition XLT 4WD

About $15 for a tester that can tell you what is wrong with truck side and/or trailer side.

https://www.amazon.com/Trailer-Test...s=trailer+light+tester&qid=1606525251&sr=8-12

 

[Jonneyo]

Thanks. I’ll test the wires. Is there a schematic of the truck wiring? The Ford part website is not helpful.

 

[07navi]

Thanks. I’ll test the wires. Is there a schematic of the truck wiring? The Ford part website is not helpful.

All those 7 pole plugs should be standard, google them and you can see graphs showing the output arrangements. Start by drawing a 7 pin plug and label the connections after sticking a test light in the truck mounted one. Sometimes a previous owner changes the arrangement of the wiring around in them. I use a stick or something to depress the brake pedal. There is a schematic for the truck in one of those 2 big red shop manuals that are year specific (in ebay). They are a must for anyone the does most of their own work.

 

[adamsdaddy]

Dielectric grease solved problems with my popup trailer and our nonprofit’s trailer. The brass or copper oxidizes very quickly since the connector is exposed to the weather and one taillight or the other wouldn’t blink so I would sand or scrape the connector and this would work for a couple months.
7 pin connectors are $15-20 at Walmart. If it was me, I would throw $15-20 at the problem-then I’d know the wiring on the back of the 7 pin was solid.

 

[07navi]

Dielectric grease solved problems with my popup trailer and our nonprofit’s trailer. The brass or copper oxidizes very quickly since the connector is exposed to the weather and one taillight or the other wouldn’t blink so I would sand or scrape the connector and this would work for a couple months.
7 pin connectors are $15-20 at Walmart. If it was me, I would throw $15-20 at the problem-then I’d know the wiring on the back of the 7 pin was solid.

I agree, I never gave dielectric much thought but now I use it extensively and auto parts stores have those connectors cheaply also. I had so many problems with the round 7 pin one I just use the little light weight 4 pin one with dielectric now.......problem solved.

 

[Plati]

Dielectric grease solved problems with my popup trailer and our nonprofit’s trailer. The brass or copper oxidizes very quickly since the connector is exposed to the weather and one taillight or the other wouldn’t blink so I would sand or scrape the connector and this would work for a couple months.
7 pin connectors are $15-20 at Walmart. If it was me, I would throw $15-20 at the problem-then I’d know the wiring on the back of the 7 pin was solid.

that would help with something thats not making connection, but the OP has a different problem .... overcurrent, not no current

 

[adamsdaddy]

@MrSticker My thought was to eliminate any possible shorts/grounding problems with the 7 pin connector’s wiring.

 

[07navi]

@MrSticker My thought was to eliminate any possible shorts/grounding problems with the 7 pin connector’s wiring.

If the little 4 pin connector has enough pins I would use that one, it solved all my 7 pin problems.