Finding a wire in a harness

[theoldwizard1]

2012 Ford Expedition EL. NO HD towing option.

I want to install a 7 way trailer connector instead of the standard 4 pin connector. One of the pins on the 7 way is Vbatt (12V). Their is a circuit, relay and fuse for this is in the fuse block. The wiring harness diagrams I have show that it is an Orange wire. Nothing shows up at the rear bumper (the blue electric brake wire IS near the rear bumper).

What is the easiest/smartest way to 1) see if this wire actually leaves the fuse block and 2) trace it as far as it goes ?

With the battery disconnected, can you remove the fuse block and get inside to inspect what wire terminates where or is it sealed ?

 

[kerrynzl]

Use a multimeter on ohms with a couple of wires with alligator clips as extensions.

One tip [I was taught by an old timer] when playing with car electrics.

Get an old headlight [sealed beam ] with a couple of alligator clips wired to it.
Use this as an ground cable from the battery while the actual ground is disconnected.

If you accidentally short circuit a wire, the headlight glows [ instead of doing a "Joseph Lucas" on the whole harness ]

 

[sselander]

I have an old "fox and hound" tone generator from my telecom toolkit that is used to trace wires, it also works well for automotive use.

 

[theoldwizard1]

I have an old "fox and hound" tone generator from my telecom toolkit that is used to trace wires, it also works well for automotive use.

I never heard it called that, but I know what you are talking about !

 

[Deadhead]

2012 Ford Expedition EL. NO HD towing option.

I want to install a 7 way trailer connector instead of the standard 4 pin connector. One of the pins on the 7 way is Vbatt (12V). Their is a circuit, relay and fuse for this is in the fuse block. The wiring harness diagrams I have show that it is an Orange wire. Nothing shows up at the rear bumper (the blue electric brake wire IS near the rear bumper).

What is the easiest/smartest way to 1) see if this wire actually leaves the fuse block and 2) trace it as far as it goes ?

With the battery disconnected, can you remove the fuse block and get inside to inspect what wire terminates where or is it sealed ?

you should be able to see the actual wires coming out of the fuse box inside the engine compartment at the firewall or possibly under the steering column area. I would open up the wrapping and get a visual on any and all orange wires. I would then pierce them ever so slightly and do a continuity test back to that fuse to verify its actually hooked up since your model of vehicle does not have the tow option.

If you actually find the wire connect at the firewall/dash area, it all about tracking it down and seeing where they dead ended the wire. Maybe simply stopped at a plug all wrapped up mid frame.

 

[theoldwizard1]

you should be able to see the actual wires coming out of the fuse box inside the engine compartment at the firewall or possibly under the steering column area.

This vehicle actually has 2 fuse boxes. The main one mounted to the radiator support, front and center under the hood. The main harness coming out of the fuse box is tightly bundled inside convoluted plastic tubing which is well over 1" in diameter.

Despite what wiring diagrams say, I'm not 100% certain that it is an organge wire !

 

[dwp99]

Will this help,
it's an All Data wire diagram for the 2012 Ford Expedition.

Look for the orange Trailer Tow Relay Battery Charge wire. it shows it in the light duty 4 pin but it might not run to the rear of the vehicle.

I've often found that the car companies will install the wiring even if it's not offered because of costs. it's cheaper to make one harness with all the wires that to make two and have to figure which Expedition gets which harness.

 

[theoldwizard1]

Will this help,
it's an All Data wire diagram for the 2012 Ford Expedition.

Look for the orange Trailer Tow Relay Battery Charge wire. it shows it in the light duty 4 pin but it might not run to the rear of the vehicle.

I've often found that the car companies will install the wiring even if it's not offered because of costs. it's cheaper to make one harness with all the wires that to make two and have to figure which Expedition gets which harness.

Thanks for looking that up and I concur with you !

In the first image (titled Heavy Duty) does All Data say where the "Trailer Tow Connector, 7 Pin" (bottom right corner) is located ? If I can find that I would be golden.

I found the blue Trailer Brake wire near the rear and I know it goes up to a connector under the dash for the brake controller (I have the mating pigtail for that), but I did not see the GY-BN (gray-brown ?) reverse wire hanging loose in the back.

 

[sabercatt]

on a light duty it is listed as not used. and never leaves the harness in engine compartment. its pin 15 in inline connector c139. labeled as cat14 (OG) and a 12 gauge wire. location: engine compartment, above LH side wheel well

 

[theoldwizard1]

on a light duty it is listed as not used. and never leaves the harness in engine compartment. its pin 15 in inline connector c139. labeled as cat14 (OG) and a 12 gauge wire. location: engine compartment, above LH side wheel well

Yes, I concur with this (my previous statement is incorrect).

I wish I had an image of C139 so I knew what I was looking for,

 

[sabercatt]

try these

 

[dudutzu905]

hope this helps,
the connector with 7 pins you are looking for is C4099, and it looks like #5 wire it is the orange wire you are looking for

 

[theoldwizard1]

try these

I couldn't ask for anything better than that !

Thanks

 

[cg81]

On the newer fords, follow harness back from the trailer connector to the first inline conductor. Probably 3or 4 feet fron the 4 pin connector. There should be everything you need supplied to the vehicle side of the inline connector. If so go to dealer and buy the harness with the factory 7 and 4 pin connectors and plug it in. There may be a fuse or relay to add to power everything up. The factory tow harness will have all the clips to attach it to the frame and will be a very clean install.

 

[theoldwizard1]

On the newer fords, follow harness back from the trailer connector to the first inline conductor. Probably 3or 4 feet fron the 4 pin connector. There should be everything you need supplied to the vehicle side of the inline connector. If so go to dealer and buy the harness with the factory 7 and 4 pin connectors and plug it in. There may be a fuse or relay to add to power everything up. The factory tow harness will have all the clips to attach it to the frame and will be a very clean install.

Maybe of F-Series, but not n Expedition. Remember, Expo's have carried over since before the current F-series.

Word on the street is that the next Expedition (2016MY? 2017MY?) will use a lot of parts from the F150.

 

[akasephiroth]

http://www.powerprobe.com/

These are amazing for stuff like this, if you can invest in one. One of the great things about them too is that you can use it to shoot power to a wire and if that would create a short the probe has a small circuit breaker on it that would blow instead of damaging your wiring.

 

[RedBKM]

I never heard it called that, but I know what you are talking about !

Triplett made the Fox and Hound. I have one of the originals but the newest one is pretty nice. It has an LED worklight and a headphone jack!
http://www.triplett.com/shop/fox-hound/

Not sure about the Expedition but on my '13 F250 the 12V trailer AUX has a relay and cuts on/off with the key. If you want it hot all the time you can remove the relay and jumper the pins in the under-hood fuse box.