no brakes and no charge from truck

[8-ball]

Ok so the other day I went to the place where the RV is stored and had opened up the slides. Then when I went to put the slides back in they became slower and stopped half way, like the battery went dead. So I figured no big deal its been sitting so I hooked the truck up via the 7 pin...still no juice so I let it charge that way for a bit. Nothing was happening. Finally I hooked a pair of jumper cables up to the battery directly to my truck and that did the trick. I mentioned this to a friend and he thought it might be a fuse in the truck since my RV is only 1 month old. Second I have a factory installed trailer brake however when I am hooked to the RV i get no brakes to the trailer, all other lights and stuff outside the RV works just not inside (should I get lights inside when hooked). Could this just be a fuse within the truck? I have a 2012 F350 Superduty Lariat Diesel 6.7L dually. I didn't get an owners manual with the truck so I have no clue which fuse it would be. My friend told me I could just buy a test light...which I did but I have no clue how to use it.

Other notes
I am a newbie to RVs, no breakers were flipped in the RV. I have no clue how the battery disconnect on/off should work so I tried both. when should I have it ON and when should I have it off. Any idea how a test light works? Any idea which fuse it would be or who I can get to fix this?

[chuckster57]

There should be a relay that has to be installed for the charge line. Haven't worked on a new truck, but I'm thinking there is a fuse that will activate the brake circuit. You can go to Ford on-line and download the owners manual. All the information you need will be in that document.

[8-ball]

Originally Posted by chuckster57

There should be a relay that has to be installed for the charge line.

So is this something I can do or will a Rv dealer do it.

[chuckster57]

You can do it. Often times when the truck is first sold the relay and instructions are in a bag usually in the glove box. Taking it yo an RV dealer would probably cost more than necessary because they would have to source the relay. If you going to take it to a dealer, take it to Ford. The Ford dealer should have the relay in stock and if the parts person is worth a darn, they will show you where it goes or print the page that shows.

[JRTJH]

I believe you have a F350 SuperDuty. If so, the "trailer tow relay/fuse package" should already be installed in your truck at the factory (on the assembly line). In the F150 series, those components are placed in a plastic bag in the glove compartment for installation by the dealer. Anyway, your truck should be "ready to tow" when it was delivered to you.

Now, under the hood, on the driver's side (tucked away under some wiring and difficult to see) is the "high voltage fuse panel".... In it, fuse #90 is the "trailer charge line". It's a 25 amp fuse and is probably the reason you aren't charging your battery.

Here's why: When the trailer battery was depleted by opening the slides, you plugged in the truck connector. That put a "high charge load" on the truck's wiring. It takes several hours to get a substantial charge to the trailer battery through that "small charge wire" in your truck's wiring harness. So, after a few minutes, when you pressed the slide switch inside your trailer, you put a "HUGE LOAD" on the battery, which was connected to the truck charge line and overloaded that 25 amp fuse. When it blew, it "disabled" all electrical charging on the "connector charge line.

Additionally, there are several other fuses in that "high voltage fuse panel" that connect the trailer umbilical plug.

#10 40 AMP Trailer Tow
#22 30 AMP Trailer Electric Brakes
#26 30 AMP Trailer Parking Lamps
#29 RELAY Trailer Parking Lamps
#70 10 AMP Trailer Backup Lamp
#90 25 AMP Trailer Charge Line


ALSO (I know, will it ever end??) On the INSIDE fuse panel (under the dash) are three fuses that affect the trailer.

#15 15 AMP Trailer Backup Lamp RELAY
#30 15 AMP Trailer Parking Lamp RELAY
#31 5 AMP Trailer Brake Control

I believe you'll find that the charge line fuse (#90 under the hood) is the reason you don't have any charge power to your trailer.

However, keep in mind that the small 18 gage charge wire simply can't carry enough amperage to recharge a dead trailer battery unless you've got literally "hours and hours" to wait. That line will "top off" a partially charged battery with several hours of towing, but wasn't designed to augment a dead battery through the umbilical connector. If you have a dead trailer battery, you should use jumper cables to your vehicle battery while the vehicle is running to prevent overloading that umbilical charge line.

You can download the Ford Owner's Manual, Diesel Supplement, Warranty Guide and other "vehicle specific information" at FORD.COM in the "owner's section" of the website.

I hope this helps.....

[8-ball]

Originally Posted by JRTJH

I believe you have a F350 SuperDuty. If so, the "trailer tow relay/fuse package" should already be installed in your truck at the factory (on the assembly line). In the F150 series, those components are placed in a plastic bag in the glove compartment for installation by the dealer. Anyway, your truck should be "ready to tow" when it was delivered to you.

Now, under the hood, on the driver's side (tucked away under some wiring and difficult to see) is the "high voltage fuse panel".... In it, fuse #90 is the "trailer charge line". It's a 25 amp fuse and is probably the reason you aren't charging your battery.

Here's why: When the trailer battery was depleted by opening the slides, you plugged in the truck connector. That put a "high charge load" on the truck's wiring. It takes several hours to get a substantial charge to the trailer battery through that "small charge wire" in your truck's wiring harness. So, after a few minutes, when you pressed the slide switch inside your trailer, you put a "HUGE LOAD" on the battery, which was connected to the truck charge line and overloaded that 25 amp fuse. When it blew, it "disabled" all electrical charging on the "connector charge line.

Additionally, there are several other fuses in that "high voltage fuse panel" that connect the trailer umbilical plug.

#10 40 AMP Trailer Tow
#22 30 AMP Trailer Electric Brakes
#26 30 AMP Trailer Parking Lamps
#29 RELAY Trailer Parking Lamps
#70 10 AMP Trailer Backup Lamp
#90 25 AMP Trailer Charge Line


ALSO (I know, will it ever end??) On the INSIDE fuse panel (under the dash) are three fuses that affect the trailer.

#15 15 AMP Trailer Backup Lamp RELAY
#30 15 AMP Trailer Parking Lamp RELAY
#31 5 AMP Trailer Brake Control

I believe you'll find that the charge line fuse (#90 under the hood) is the reason you don't have any charge power to your trailer.

However, keep in mind that the small 18 gage charge wire simply can't carry enough amperage to recharge a dead trailer battery unless you've got literally "hours and hours" to wait. That line will "top off" a partially charged battery with several hours of towing, but wasn't designed to augment a dead battery through the umbilical connector. If you have a dead trailer battery, you should use jumper cables to your vehicle battery while the vehicle is running to prevent overloading that umbilical charge line.

You can download the Ford Owner's Manual, Diesel Supplement, Warranty Guide and other "vehicle specific information" at FORD.COM in the "owner's section" of the website.

I hope this helps.....

This helped a ton. I will work on replacing those fuses. 2 questions. If I use my test light on those fuses will it tell me if they are bad. 2nd If I add a few batteries to the RV will that help in keeping the draw on the charge line better or would the opposite be the case? Shouldn't the batteries charge when hooked to 50amp service? If so should battery disconnect On/OFF be on or off?

[JRTJH]

Originally Posted by 8-ball

This helped a ton. I will work on replacing those fuses. 2 questions. If I use my test light on those fuses will it tell me if they are bad. 2nd If I add a few batteries to the RV will that help in keeping the draw on the charge line better or would the opposite be the case? Shouldn't the batteries charge when hooked to 50amp service? If so should battery disconnect On/OFF be on or off?

I'm glad it helped. Yes, if you use a "12 volt test light", you'll get the light on both sides of a good fuse and only on one side of a bad (blown) fuse. To answer your question about adding batteries, if you add batteries, you'll increase the load on the charge line (assuming you use the batteries to power your RV) so effectively, you'll increase the time and amperage requirement with additional batteries. Yes, the batteries do charge when your RV is connected to shore power (30 or 50 amp campground power source). You must have the "battery cutoff switch" set to the ON position for the converter/charger to be electrically connected to the battery bank, so if you want charging to occur, turn ON the "battery cutoff switch"............

[DWBinRI]

Check for power at the back of the truck at The Trailer Connection and ensure the 12 volts is there when you turn the key on I just went through this with my trailer and truck and ended up finding out that the power connection to the truck connector was not good the trailer side of the cable had spread pins

Sent from my SM-G920V using Tapatalk

[Pull Toy]

Probably a good idea to also check your trailer GROUND pin on your hitch. Also be aware that your charging rate will most likely be slower at the hitch than if you use jumper cables. Your 7 pin was meant to hold a charge, not start from zero.

Good Luck,

[CaptnJohn]

This could save a ton of research time~~ printed and will be kept in my electrical box in the 5er.Thanks from me too!

Originally Posted by JRTJH

I believe you have a F350 SuperDuty. If so, the "trailer tow relay/fuse package" should already be installed in your truck at the factory (on the assembly line). In the F150 series, those components are placed in a plastic bag in the glove compartment for installation by the dealer. Anyway, your truck should be "ready to tow" when it was delivered to you.

Now, under the hood, on the driver's side (tucked away under some wiring and difficult to see) is the "high voltage fuse panel".... In it, fuse #90 is the "trailer charge line". It's a 25 amp fuse and is probably the reason you aren't charging your battery.

Here's why: When the trailer battery was depleted by opening the slides, you plugged in the truck connector. That put a "high charge load" on the truck's wiring. It takes several hours to get a substantial charge to the trailer battery through that "small charge wire" in your truck's wiring harness. So, after a few minutes, when you pressed the slide switch inside your trailer, you put a "HUGE LOAD" on the battery, which was connected to the truck charge line and overloaded that 25 amp fuse. When it blew, it "disabled" all electrical charging on the "connector charge line.

Additionally, there are several other fuses in that "high voltage fuse panel" that connect the trailer umbilical plug.

#10 40 AMP Trailer Tow
#22 30 AMP Trailer Electric Brakes
#26 30 AMP Trailer Parking Lamps
#29 RELAY Trailer Parking Lamps
#70 10 AMP Trailer Backup Lamp
#90 25 AMP Trailer Charge Line


ALSO (I know, will it ever end??) On the INSIDE fuse panel (under the dash) are three fuses that affect the trailer.

#15 15 AMP Trailer Backup Lamp RELAY
#30 15 AMP Trailer Parking Lamp RELAY
#31 5 AMP Trailer Brake Control

I believe you'll find that the charge line fuse (#90 under the hood) is the reason you don't have any charge power to your trailer.

However, keep in mind that the small 18 gage charge wire simply can't carry enough amperage to recharge a dead trailer battery unless you've got literally "hours and hours" to wait. That line will "top off" a partially charged battery with several hours of towing, but wasn't designed to augment a dead battery through the umbilical connector. If you have a dead trailer battery, you should use jumper cables to your vehicle battery while the vehicle is running to prevent overloading that umbilical charge line.

You can download the Ford Owner's Manual, Diesel Supplement, Warranty Guide and other "vehicle specific information" at FORD.COM in the "owner's section" of the website.

I hope this helps.....

[8-ball]

Thanks again everyone for all the info here. Printing this out