2005 FX4, no center console. Looking for a place to pick up 12 volts when the truck is in reverse to trip a relay. Don't see a very easy way to get it at the fuse box. I would like to put the relay somewhere behind the dash. Anyone know where to tap into this in the cab?

I really wish they would have used a heavier wire to feed the back up voltage to the 7 wire trailer connector. It's only rated at 5 amps.

Thanks

 

The Trailer Tow reversing circuit is accesable in the driver's side kick panel.

The output of the Trailer Tow Reversing Circuit Contacts ( the 20 AMP ckt ) :
C238 Conector pinout:


C238 Location :


I don't know what you are looking at for the 7 pin trailer tow reversing lamp circuit to call it 5 AMPs.
The 2005 owners manual, and the 2006 EVTM cell 95-1 both call this a 20 A fused circuit ( F10 ).



The 20 AMP fuse feeds the Trailer Tow adapters for the Parking Lamps and the reversing lamps.

Full Thread that Bob started :
https://www.f150online.com/forums/sh...d.php?t=233512

 

I know it's fed from a 20 amp fuse shared with the running lights but the trailer tow documentation list the Maximum Allowable Current as 5 amps. I'm assuming this is because of the somewhat small gauge BK/PK wire. Not sure but it looks like 14-16? I was concerned about running two 55 watt lamps off of this feed.

Edit
Hmm, now that I see the additional drawings it looks like its 18 gauge. Am I missing something? That seems really small to me. I guess I don't really understand the 7 pin trailer connector. Is the back up voltage only provided to activate a relay on the trailer? It must be since it is so small.

 

I see the chart where it lists 5 AMPs, 14 AWG wire on page 5 of the traielr tow adapter install directions.
I am guessing that is from a shared fuse ?? The 2 together is spec'd max 12.5 AMPs on a 20 AMP fuse ( 5 A reversing lamps + 7.5 A parking lamps ).

A few members have installed 55 W clear fog lamps on the system, without issue ( this is 9.16 AMPs total for the 2 lamps ). I am only running 2 AMPs on it with the Truck Lite LED backup lamps, so 2 AMP load is all I can comment on, myself.

Additional drawings 18 AWG ?? Missing that one. Which page is that on I took a quick look over the trailer tow adapter install directions.

Back to your actual question :the connector in the kick panel is the wire you were looking for hooking up the relay to. Did you get a good feel for this ?

 

When I said additional drawings I meant the C238 connector pinout diagrams. I didn't see them initially. I think you fixed that link while I was responding. The pinout description has number 13 circled and it's the BK/PK and lists it as 18 Gauge.

The 9 amps is way to much (in my opinion) for that small wire. It probably works OK for back up lights since they are only on short duration so the wire doesn't have time to get too hot. I'd definetly be concerned using them for extended periods for utility purpose that way though.

Yep, I got it and found the wire under the door sill. I didn't have too much time to work on that today but I was having trouble getting the kick panel off. Also wondering if I could pick it up coming out of the fuse box or somewhere in between. Has to get from the passenger side to driver's side somehow. Anyway, you answered my original question and I at least know one place I can get B+ for Back Up Relay. Those drawings helped as they add some detail not in the owners manual or Trailer Tow Package documentation.

Thanks for the help.

 

Duhh.. Thought you were refering to the Trailer Tow docs again, that I obviously did not read too well the first time, so I figured I missed it in there again. I didn't even go back to the connector pin out looking for that. Thanks.

Got me if the other members use them this way. Those that install them, put in a On-Off-On switch. One of the ONs is with the reverse lamps ( reversing CKT ) the other On is constant run. I don't know if it actually gets used or not, nor if it is, what the outcome is. I use mine quite a bit both ways, but again I am only using 2 AMPs draw on the 5 AMP suggested.

That is the other place you will find it as well, vs. the kick panel by the parking brake. The other connector by the Central Junction box is C270E

Pinouts :


Location :


These might be a PITA to get to, with the Central Junction box there, but I am not 100% certain on that, I have not been in there since the Fog light mod write up.

 

Perfect, thanks very much. Took a quick look and that connector is just above the fuse box, not to hard to get to and I can easily see the BK/PK wire 5th one up.

Thanks again for looking this up, been a big help. I believe I have all the information I need to finalize my layout.