No 12V on 7 way trailer connector

[Grumpy7159]

I tried to run a water pump off my 7-pin connector and there was no power. 2017 F350. There was a module under the truck that has something to do with the electric brake and trailer wiring. I gave up on the pump idea. My trailer break away battery does get charged on the road. One of Ford's better ideas?

[moto_209]

ok i was able to go over to the MH a few days ago. I forgot my voltmeter but thats ok. My trailer was hooked up to it in storage.

So my lights i installed in the trailer only worked with the key turned on, the lights were not bright so i turned the engine on and the lights brightened a bit more. I wondered why they did not work on my last trip when the coach was running. So the only thing different were the head lights being on. So i turned lights on and bam trailer inside lights turned off.


So i have power when ignition on and head lights off. Anyone have an idea how to change or bypass this?

#4 and #63 in fuse panel are installed and looked to be ok. (#4 looked like a relay or internal fuse)?

My pickup (2014 2500HD Duramax) has continuous power with out doing anything to the truck, no keys head lights on, just sitting all weekend and i can go test power and it will be there.

Im going to when i have more time trace back the trailer wiring from the connector to end of line.

[Duckogram]

Originally Posted by moto_209

ok i was able to go over to the MH a few days ago. I forgot my voltmeter but thats ok. My trailer was hooked up to it in storage.

So my lights i installed in the trailer only worked with the key turned on, the lights were not bright so i turned the engine on and the lights brightened a bit more. I wondered why they did not work on my last trip when the coach was running. So the only thing different were the head lights being on. So i turned lights on and bam trailer inside lights turned off.


So i have power when ignition on and head lights off. Anyone have an idea how to change or bypass this?

#4 and #63 in fuse panel are installed and looked to be ok. (#4 looked like a relay or internal fuse)?

My pickup (2014 2500HD Duramax) has continuous power with out doing anything to the truck, no keys head lights on, just sitting all weekend and i can go test power and it will be there.

Im going to when i have more time trace back the trailer wiring from the connector to end of line.

#4 is a micro relay (see post #10)
As for the lights being dim and then cutting out when the load increases leads me to think there is grounding issue. YMMV

[BehindBars]

Originally Posted by moto_209

ok i was able to go over to the MH a few days ago. I forgot my voltmeter but thats ok. My trailer was hooked up to it in storage.

So my lights i installed in the trailer only worked with the key turned on, the lights were not bright so i turned the engine on and the lights brightened a bit more. I wondered why they did not work on my last trip when the coach was running. So the only thing different were the head lights being on. So i turned lights on and bam trailer inside lights turned off.

So i have power when ignition on and head lights off. Anyone have an idea how to change or bypass this?

#4 and #63 in fuse panel are installed and looked to be ok. (#4 looked like a relay or internal fuse)?

My pickup (2014 2500HD Duramax) has continuous power with out doing anything to the truck, no keys head lights on, just sitting all weekend and i can go test power and it will be there.

Im going to when i have more time trace back the trailer wiring from the connector to end of line.

This smells like a grounding issue. An example is on simple four wire trailer wiring running incandescent bulbs. taillights seem to work OK until the brakes are applied, then all lights go very dim. The problem is the ground connection is so resistive that it cannot handle the current of all the lights at once. Your problem seems the similar.

You have 12 volts to the trailer interior lights, but when you turn on the motorhome headlights, you also turn on the trailer exterior lights. The added load of the tail and marker lights on the trailer increase the load to the point where there is so much voltage drop in the ground connection, the voltage presented across the trailer interior lights in unacceptably low.

I suggest you troubleshoot the grounding path between the trailer and the motorhome. As a temporary troubleshooting aid, you could even add a jumper cable between the trailer frame and motorhome frame to see if it eliminates the problem by temporarily improving the ground path. Also, your ground wire problem, if you have one, could just as easily be on the trailer side of things as on the motorhome side.

[itsjb5]

Originally Posted by BehindBars

This smells like a grounding issue. An example is on simple four wire trailer wiring running incandescent bulbs. taillights seem to work OK until the brakes are applied, then all lights go very dim. The problem is the ground connection is so resistive that it cannot handle the current of all the lights at once. Your problem seems the similar.

You have 12 volts to the trailerinterior lights, but when you turn on the motorhome headlights, you also turn on the trailer exterior lights. The added load of the tail and marker lights on the trailer increase the load to the point where there is so much voltage drop in the ground connection, the voltage presented across the trailer interior lights in unacceptably low.

I suggest you troubleshoot the grounding path between the trailer and the motorhome. As a temporary troubleshooting aid, you could even add a jumper cable between the trailer frame and motorhome frame to see if it eliminates the problem by temporarily improving the ground path. Your ground wire problem, if you have one, could just as easily be on the trailer side of things as on the motorhome side.

Don't forget if you are getting voltage from the truck your ground has to come from truck also. Check power and ground at truck. Don't use a volt meter use a homemade test light. I use1157 or so tail light bulb you can check with volt meter and may show 12 volts but will not light the bulb. Green corroded wires??

[BehindBars]

Originally Posted by itsjb5

Don't forget if you are getting voltage from the truck your ground has to come from truck also. Check power and ground at truck. Don't use a volt meter use a homemade test light. I use1157 or so tail light bulb you can check with volt meter and may show 12 volts but will not light the bulb. Green corroded wires??

A separate 12 volt lamp could be used as a test load, but the OP already has a load to use for testing: the trailer lights.

[Nightfighter]

You have to order the charge package from the factory when your truck was built. I have a 2017 F350 and, unfortunately, did not have the relay and fuse and wiring put in for charging. I guess you could do it yourself, my dealer wouldn't even touch the job. Soooo ... I have to make sure my house batteries are charged up to make sure the brakes work on the camper.

[itsjb5]

Did you not have a 7 pin trailer plug from the factory? If so the wires are there you may just need to insert a fuse and relay. 27 year Ford tech and I know relays came in the glove box for owners to install if they needed it. Owners manual will show the position of TRAILER relay and fuse positions. Also note TRAILER park light fuse and turn signal fuse.

[Thomas ho]

e trailer has a answer on how charge works on 2017 ford super duty. no relay or fuse required. GOOGLE IT.

[BehindBars]

Originally Posted by Nightfighter

You have to order the charge package from the factory when your truck was built. I have a 2017 F350 and, unfortunately, did not have the relay and fuse and wiring put in for charging. I guess you could do it yourself, my dealer wouldn't even touch the job. Soooo ... I have to make sure my house batteries are charged up to make sure the brakes work on the camper.

The thread is in the Sunseeker and Forester motorhome forum and is about a class C motorhome that Forest River built on a Ford E-450 cutaway chassis. Forest River decides how the chassis will come from Ford. The buyer of a class C RV typically just gets a finished product. There is no opportunity to "order the charge package from the factory when your truck was built".

I already established that with my 2019 E-450, the 12 volts is present on the 7 pin trailer outlet as Forest River delivered the motorhome. No additional fuse or relay was required. The OP also noted 12 volts present as it lights his trailer interior lights, at least until the motorhome headlights are turned on.

[Odyknuck]

On my F250 #4 pin is not active unless the engine is running. Both being a Ford product I suspect they are wired the same.

[flyflotrtim]

truck must be running, plus if you have push button start you have to leave the key fob inside the truck and fully close the drivers door when you get out to check for voltage.

This does apply to my F-150, 2019 Lariat. Don't ask me how I know.

[BehindBars]

Originally Posted by flyflotrtim

truck must be running, plus if you have push button start you have to leave the key fob inside the truck and fully close the drivers door when you get out to check for voltage.

This does apply to my F-150, 2019 Lariat. Don't ask me how I know.

Are you saying for sure that the E-450 truck must be running? That is not what I personally measured on mine.

BTW, there is no smart key fob nor a push button start on a 2018 E-450 based Sunseeker, the topic of this thread. The key doesn't even have an immobilizer chip in it.

[DavidWJ]

Generally, there is no voltage at the trailer brake pin until the trailer brake controller is active. Depending on the controller type, just stepping on the brake may apply a small voltage, but inertial controllers won't apply voltage until the tow vehicle starts slowing. You can test the voltage with the manual control, if you have that capability, and the trailer brakes should fully apply when the manual control is fully applied.
Honestly, vehicles are becoming some ridiculously automated that you may not have a manual control feature.

[BehindBars]

Originally Posted by DavidWJ

Generally, there is no voltage at the trailer brake pin until the trailer brake controller is active. Depending on the controller type, just stepping on the brake may apply a small voltage, but inertial controllers won't apply voltage until the tow vehicle starts slowing. You can test the voltage with the manual control, if you have that capability, and the trailer brakes should fully apply when the manual control is fully applied.
Honestly, vehicles are becoming some ridiculously automated that you may not have a manual control feature.

Not that I disagree with your explanation on the brake pin voltage, but the OP has questions only about the +12 AUX output, pin #4 to ground.