4-flat to 5-flat missing relay?

[Golfnomo]

My 05 Expedition came with the standard 4 -flat plug, and the 5th wire for the backup circuit was in the harness taped inside the wire loom. I installed a 5-flat connector adding the backup circuit. There is no voltage on the backup circuit which leads me to believe that there is a missing relay/fuse. The trailer brake lockout solenoid is operating okay if I plug the 5th connector into the running lights, so we can eliminate that. The local Ford dealer is clueless on the missing component and the Drawtite shop referred me back to the dealer. The user manual refers to an "R301" relay that looks like it takes care of the problem. It says it is a dealer servicable item only. Problem is the parts guy at this Ford dealership remains hung up on how there should either be a 4-flat or 7 round connection and is entirely puzzled over the mysterious 5th wire in the harness and what is needed to energize it.<br /><br />So, do I put the 4 wire back on it and use the 4-5 flat adapter splicing into the reverse lights circuit, do I install a 7-round, or can someone help me with the missing relay/fuse situation so I can use the 5 wires provided in the harness?<br /><br />By the way, the 05 and I think 04 Expedition does not have the same power distribution center or location as earlier models

 

[Silvertip]

Re: 4-flat to 5-flat missing relay?

Check your owners manual for fuse block orientation and fuse/relay locations. It is not uncommon for manufacturers to include wiring in harnesses that are not used in "specific" vehicle builds. Your truck may not have a specific trailer package so the wire is simply not connected and the relay/fuse not installed although the provisions are obviously present. You will likely have more than one fuse/relay panel so check your manual carefully. The reverse wire should not tie into any other wire on the trailer except the reversing solenoid.

 

[KM2]

Re: 4-flat to 5-flat missing relay?

Are you checking for voltage with the vehicle in reverse? <br /><br />Use the adapter and forget about everything else. It will work fine.

 

[gonefishie]

Re: 4-flat to 5-flat missing relay?

So an 05 model come with a flat plug? I thought if they have a factory installed tow package than the wiring harness would have a round connector. If that a funky Ford thing than I'll make them fix it

 

[Golfnomo]

Re: 4-flat to 5-flat missing relay?

Thanks for the quick replies. On checking voltage, yes I checked it in reverse. I spoke with another Ford dealer that basically confirmed that the harness is the same when you get the flat4 or the round7 and that the wire is likely not connected to anything since it is not the HD tow package. I have decided to splice the 5th wire into the reverse lights and put an end to the mystery (misery). Thanks Again!