Mystery wires in my Ranger harness at the back bumper

[lil_Blue_Ford]

So, I have the back bumper off my green 2000 Ranger. It’s the loaded XLT complete with factory trailer wiring and all. Well, there’s three unidentified wires in the factory plug. They dead-end there, the other 5 wires continue on to the tail lights. I pulled out my electrical book, but either I don’t know what I’m doing with the book yet, or there’s no good way to figure it out without going through every circuit in the book. Curious as to if anyone happens to know what on earth they are for.

So, C403M is the frame side of the connector and C403F is the bed side and as you can see, there’s no wire on the bed side for pin 3, 6, and 8. Yet on the frame side, there’s a wire in each. I didn’t see any reason to suspect they branch off for any of the other connectors in that frame harness so I checked the next main connector forward which up towards the firewall area and those three wires are present there as well, but I still don’t know what they do.

So there it is, pin 13, 25, and 39 in C309 hold those wires on both sides.

 

[sgtsandman]

Maybe there was an option for a 7 pin trailer plug at one point?

I'll try to remember to dig through my electrical manual for the 2011 and follow the wires if the 2011 is wired the same. As little as they changed these trucks over the years, the harness should be the same.

 

[pjtoledo]

page 10-2, upper right is note stating circuit 57 (BK) is a ground.
still looking for the others.

circuit 9 terminates as not used, it's a leg off circuit 3 left front park turn. page 90-3

circuit 5 is same, except right front park turn.

it appears you could use those for trailer turn signals without brake light interference.
possible a hold-over from the separate amber rear turn signals.

do they come on with park lamps? blink with turn signals?

follow black arrows D & E back to page 90-2, they are turn signals/hazard flashers.

 

[lil_Blue_Ford]

Maybe there was an option for a 7 pin trailer plug at one point?

I'll try to remember to dig through my electrical manual for the 2011 and follow the wires if the 2011 is wired the same. As little as they changed these trucks over the years, the harness should be the same.

That was my original thought, but it only lasted long enough to realize that if it was wiring for an optional 7 pin trailer plug, those wires should be grouped with the trailer wires that terminate in a different plug (or in my case where someone hacked off the factory plug).

My next thought was to wonder if it was wiring for a cap, like a 3rd brake signal and power for a light for the bed.

 

[lil_Blue_Ford]

page 10-2, upper right is note stating circuit 57 (BK) is a ground.
still looking for the others.

circuit 9 terminates as not used, it's a leg off circuit 3 left front park turn. page 90-3

circuit 5 is same, except right front park turn.

it appears you could use those for trailer turn signals without brake light interference.
possible a hold-over from the separate amber rear turn signals.

do they come on with park lamps? blink with turn signals?

follow black arrows D & E back to page 90-2, they are turn signals/hazard flashers.

Interesting.

I knew about 57 (BK) for the ground (although oddly enough my trailer wire bundle off the factory harness is supposed to contain part of 57 (BK), but there is no black wire in the group but a white wire comes up as the ground when I probe it and that’s what was hooked as a ground).

I didn’t trace the wires that continue on to the bed, but I’m sure there’s a left and right turn signal/tail plus a backup light wire in there. Wonder if I could tap off the backup light circuit to do trailer backup lights or if I’ll need a relay for that. Anyway…

So circuits 5 and 9 are left and right signals. Might be a really weird hold over from the rear amber signals, guess they had a lot of extra frame harnesses left over when they did the change or something, lol. I’ll probe them and see what happens with park lamps/turn signals/flashers/brake lights.

So that leaves circuit 511 as still unknown…

 

[pjtoledo]

outside cargo, high mount stop light.
starts at brake pedal.
page 90-4

I'm not sure why a brake pedal has anything to do with a cargo light, but, that's what the book says.

 

[lil_Blue_Ford]

outside cargo, high mount stop light.
starts at brake pedal.
page 90-4

I'm not sure why a brake pedal has anything to do with a cargo light, but, that's what the book says.

Interesting. I’ll do some probing today. Going to be a little irritated if there is a 3rd brake light wire in the harness there, I’ve always had to tap into the 3rd brake light wiring in the cab and run a wire back to do the 3rd brake light on a cap because you need a module or to get an isolated brake wire for those. Having a brake wire already back there simplifies any future work.

 

[2011Supercab]

possible a hold-over from the separate amber rear turn signals.

Or if that part of the harness is the same as the Mazda B series, which kept the amber turn signals to the end of their run.

 

[lil_Blue_Ford]

I haven’t got to probing the wires yet, but I will soon. Monday I ended up going to my buddy’s to use my big welder so I’ve been slaving away at welding instead of wiring. Hopefully I’ll be back to wiring tomorrow along with patching my bed and some other stuff. I’ll keep everyone posted when I get to it what probing the wires shows.

 

[RobbieD]

so I’ve been slaving away at welding instead of wiring

For some of us clumsy individuals, those two can be one and the same.

 

[Blmpkn]

For some of us clumsy individuals, those two can be one and the same.

I've clumsily pulled the trigger on my mig just to have the wire run right into the tip of my finger once..

Not sure what sucked worse.. the whole getting stabbed part of the equation.. or the zap.

Do not reccomend.

 

[RobbieD]

I've clumsily pulled the trigger on my mig just to have the wire run right into the tip of my finger once..

Not sure what sucked worse.. the whole getting stabbed part of the equation.. or the zap.

Do not reccomend.

Now that's being creative!

I'll have to try it sometime.

When it comes to stupid shit, there ain't much I ain't done

 

[lil_Blue_Ford]

My Lincoln AC-225 stick welder has electrical tape over a screw that holds the handle together. You wouldn’t think you could feel the amps running through that screw with welding gloves on, but I assure you, it is possible. Believe I was running some 7018 1/8” rod on some 1/4” steel at the time I discovered this so it was up there a bit on amperage. Do not recommend. Amperage is what kills, not so much voltage.

I’ve also been blasted by an arc jump out of a house panel (240 volts), it was super hot and tropical rainforest level humidity because we had just been pounded by rain when it happened. I was working on a garage sub panel and there was enough humidity that it arced a good 8-10“ out of the panel to grab me. That one was really bad. When your heart is pulsing to 60 Htz, its really all sorts of not good. I don’t work on electrical when it’s stupid humid now. Or weld.

 

[lil_Blue_Ford]

So I have confirmation. The three “mystery” wires are indeed a left-turn, right-turn, and brake. So any Ranger with these ”extra” wires has a brake light signal they can tap into in the factory harness there for a third brake light on a cap or camper. Additional signal wires too. Pity there isn’t an extra backup light wire available. I’m not sure if I can tap into the regular backup light circuit for some auxiliary LED lights of if I’ll have to run a relay. I’m thinking it might have to be a relay…

Oh, yeah, if you need to tap into it, visit a junkyard to source a plug with a bit of wire. Poke a hole in the seal over the correct pin, and shove in the new piece of wire in the factory plug. You have to pull the retainer in the plug before shoving the wire in, but that would get you a weatherproof plug connection for your tap for a third brake light power wire and you could just ground to the bed for the light.