No 12v+ at Ford truck 7 way trailer plug mystery solved?

G

gulfcoast john

New member
No 12v+ at Ford truck 7 way trailer plug mystery solved?

Hi Friends!

In Nov we dropped the trailer for EOH brake work at a reputable shop in Marathon. For $3000 many wear items were replaced, and the $1,000 Brakerite actuator. Owner upgraded the breakaway trailer battery from the 7AH mini to a U1-1 lawn tractor battery. He said the system used that battery in other ways than instances of total hitch separation, which I didn’t realize.

The new trailer brakes worked great on our return in Jan and to the Hontoon Hoot in Mar, but did not work on the back from Hontoon. All trailer lights worked fine. Troubleshooting revealed the new larger trailer battery was stone dead at 10.2v. Checking the 7 way plug, there was no voltage between the orange 12V+ and white ground pins. Confirmed that with a LED 7 way test plug.

“Your vehicle may have electrical items, such as fuses or relays, related to towing. See Fuses p 317.” Fuse #27 is for ‘Trailer tow battery charge relay (if equipped).” There was no fuse in that slot, so I added one but we’ve been towing with this truck for over a year. Also replaced # 54, “Trailer brake control module.” Cleaned and sanded the plug and applied lots of BoeShield T-9. In my experience, Boeshield T-9 can be a great substitute for understanding how electrical circuits work. No Joy.

It turns out that Ford designed this so there is no 12v+ trailer plug output unless a real trailer is connected and the truck foot brake is activated for at least 3 seconds. It’s not fooled by the 7 pin tester. Trucks like mine with a factory brake controller have a “TRM module” that controls the 12v output to the trailer battery with no fuses or relays. This is buried in a Technical Service Bulletin. The official Ford position on why this information is not in the owner's manual is “because then it wouldn’t be any fun, and girls just want to have fun.”

I replaced the dead battery with a new one, plugged in the 7 way trailer plug, hit the brakes for over 3 seconds, and the actuator pump ran. I measured 12.80V across the trailer battery at 1500 RPM with lights off (12.66 when disconnected). I would have expected 13.1v or so.

My working theory is that somehow only the 12v+ slot was dirty or corroded and that the Brakerite actuator pump was operating only off the trailer battery, which eventually discharged to dead.

I’m open to any other theory or suggestions.

I hope this can save some time and research for other Ford drivers if they run into this issue.

Happy Electrical Gremlin Chasing!
John
 
First, I have a 2005 ford F250 but I don't have a factory brake controller. I do know that the 12 Vdc power out the rear is only turned on when the engine is running. It runs through a relay in the engine compartment that goes ON when the ignition switch is on, as well as a fuse. If the brake pedal switch controls the 12 Vdc, one wouldn't be able to charge the battery unless you're applying the brakes. I don't know if this is enough to charge the battery.

That would be bad for me since I use the 12 Vdc line to run the refidge when I'm traveling. The EOH battery is long gone.

I do feel that the IR (voltage) drop from 13.6 to 12.8 Vdc is reasonable given that the hydraulic motor is running.

Boris
 
Thanks, I think this may have helped me this weekend with my camper tail lights and will come in use going forward. My lights don't seem to ever work right away and maybe this is the solution. We have a new trailer to try this out on too...
 
It the trailer brakes were working only off the battery, what initiated the brake accentuation? (especially since it is proportional to the gain setting on the controller?). I think you were correct about the corrosion, and it may have been more than just the 12+ pin. Also perhaps the "brain" of the trailer brake controller in the Ford Truck had to "see" that a battery before it worked?

The trailer Tow battery relay is for charging batteries in 5th wheel or travel trailers I believe, since they will require up to 30 amps charging as the truck goes down the road? It is the blue wire--see below. I don't know how much current the Blue wire (controller brake output) draws, but it may have also been corroded. I believe the blue wire will carry up to 12 amps. Although the U1 (lawn tractor battery is about 20 amp hours, and 250 to 300 CCA), I believe that most of the current for the brake hydraulic motor is supplied thru the blue wire...

I have the banks gauges on my truck--and the alternator only puts out what is "needed". It is not unusual to see 12.6 or 12.8 volts going down the road. It all tends toward more efficiency of fuel consumption!

From E-trailer wiring guide:

faq043-vehicle7waydia-ver2_2_800.jpg
 
John, I believe you got it all correct in your original post above. The Ford OEM brake controller isn't always better than the aftermarket stuff, other than you get a lot of good information displayed on your dashboard with it. My 2016 F150 did not come tow package ready. However all Fords come with some wiring for towing. IN that truck I set up my own 12vt accessory wire and everything was hunky dory at the connection in the rear. However, with my new 2019, I went with the tow package and had them add the OEM controller. The truck has to sense a trailer back there before it will send juice to that 7th pin. And sadly, it also cuts the juice when you shut the truck down. Will, maybe sadly, maybe not. I like to have the power remain on when I'm boaterhoming as I also have a "toad" system I set up to keep my boat battery charged. OTOH, since the truck shuts that pin down when you shut it off, you won't drain your truck battery. The EOH actuator uses that 7th pin, the 12 vt towing battery charger as they call it, for it's power. IF all is wired properly, that wire is also hooked up to your brake away battery charger to keep it charged. (Ie, the accessory pin providing 12 vts from your truck, is providing power to both the brake away battery to keep it charged, and to the EOH actuator.)Then the "blue" wire from your brake controller is what then controls the amount of PSI of hydraulic fluid sent back to your trailer brakes. And as you stated above, none of this happens until you hook up a real trailer, and stomp on the brakes for a few seconds, until your dashboard says trailer connected! With Midnight Flyer, which was strictly electric brakes, that 12vt pin was wired to keep the brake away battery charged. Then I had also hooked up a wire in parallel there, to go up to a plug for my "Toad" system. I installed that plug near the top of the trailers bow stop. Now with my new truck and new boat, I don't have a toad system hooked up yet. However, knowing about how Ford has that 7th pin set up, I ran a separate set of 10 gauge wires from my trucks battery to a plug in the back of my bed, just inside the tailgate. My plans are to make a new toad system that will plug into that, so that I will have plenty of juice to keep the boat battery charged while boaterhoming, and not have to deal with the Ford wiring that will just be charging the brake away battery and providing juice to the EOH. Clear as mud? Colby
 
Colby I may be misunderstanding you: But the blue wire is what runs the pump on the E/H, or the magnetic acvcentator on your pure electric brakes.

The red wire has a constant 12 V (12.6 to 14 v) and can be used to charge the boat batteries, as well as in my case my secondary camera which is on the top of the boat for viewing behind the boat when driving.
 
Colby I may be misunderstanding you: But the blue wire is what runs the pump on the E/H, or the magnetic acvcentator on your pure electric brakes.

The red wire has a constant 12 V (12.6 to 14 v) and can be used to charge the boat batteries, as well as in my case my secondary camera which is on the top of the boat for viewing behind the boat when driving.
Click to expand...

Bob, regarding the EOH actuator, the blue wire activates the pump which in turn pressurizes the brakes. And on purely electric brakes, then it also energizes the magnets in the brake shoes. However, the EOH actuator also uses the accessory 12 vt wire, otherwise called the tow battery charger power wire, to power the EOH actuator. (I like red for this wire better, but it is the black wire below in the schematic.) IOW, for your EOH actuator to work, it has both the blue wire from the brake controller, along with the 12 vt accessory wire providing 12 vts, and of course the ground wire. Both your EOH actuator and your break away battery should be hooked up to the 12 vt wire. Which on the Ford OEM brake controller, is only energized when the Ford recognizes a trailer hooked up. (And after you press the brakes for a second or two once your Ford is started.) Below is a schematic showing the Dexter EOH actuator, with a break away battery in the mix as well. BTW, I'm not exactly sure what the 12vt accessory wire going to the EOH actuator is really there for. If you don't hook the boat up to the truck, and have a charged break away battery, and pull the break away cable, the EOH actuator will work until that small 9+ amp hour battery dies.... I just know I hooked it up like it calls for and it works. (I still liked my purely electric brakes better. Simplicity! :mrgreen: Colby

EOH_wiring.jpg
 
Colby the differential voltage of the blue wire is what controls the amount of pressure generated by the pump. Same for the magnet field on the electromagnetic brakes. The controller is what "decides" how much power to apply--in in this case it is variation of voltage, via the blue wire.

No debate that the red wire (positive 12 volts, to power circuit boards) goes into the pump module. It remains a constant 12.6 to 14 volts, depending on alternator output--it does not vary with application of the brakes. The blue wire does that thru the

No argument that the trailer has to be hooked up.

Trailer-Wire-Color-Codes-Diagram.jpg
 
Looking more at that schematic, it appears the EOH controller needs the 12vts to operate, rather it gets it from the trailer break away battery, or the pickups battery. The EOH can pull current from the break away battery if the 12vt accessory connection from the pickup is an open circuit, or not providing enough "juice". When the EOH actuator is operating with the break away cable pulled, then it's just full on. I understand the blue wire from the controller just sends out a varying voltage to regulate the EOH actuator or the magnets on electric brakes. The nice thing (simplicity) with fully electric brakes, is you only have the one blue wire from the controller (along with ground) for them to work. (Of course you still have to hook up a break away battery, but even the wiring with that is fairly simple. One side of the break away switch to the break away battery, the other side of the break away switch to the blue wire going into the brakes.) John, if your break away battery was dead, I suspect that the 12vt accessory circuit between the trucks battery and the break away battery was open. Or as you indicated, the contacts were dirty or corroded so not providing enuf voltage and current to keep the break away battery charged. (Or the break away cable got pulled somewhere along the way.) Colby
 
Only one minor comment I'd add after just installing and wiring my EOH system a few wks ago. I selected a Hydrastar actuator, a DrawTite controller mounted in the tow vehicle cab (2003 Expedition) and a Tekonsha Breakaway Switch system with a 5 amp-hr battery. Look up your actuator's installation instructions, mine has a separate "yellow" wire to specifically connect the breakaway switch's engagement wire instead of pigtailing with the blue brake activation wire. I think in actuality the yellow and blue wires are connected together in the actuator (Hydrastar), this was probably done to avoid having to pigtail to the blue wire.
 
Colby, that makes sense. I also suspect Bob is right that the controller might cut power to the pump if it senses no voltage from the trailer mounted breakaway battery, even when there is no 12v voltage from the truck to keep that same battery charged when the ignition is on, a trailer is connected, said trailer has working brake lights, and that the driver has previously pressed the truck foot brake for over 3 seconds on this outing.

I could test that theory by disconnecting that battery and activating the cab brake controller, but it’s raining and I’m lazy.

It seems to me that a way larger than 10AH breakaway battery is indicated here. Someone with an ammeter should measure amps drawn off the breakaway battery with the breakaway switch activated. Dora-Jean, the Titan supplied wiring is all ‘keyed’ looms and plugs that seem foolproof (and the shop owner did the connections, not me).

I store the trailer with the plug hanging down (no rain) but not to the ground. The gravel lot can get dusty, and grime and spiders seem to find homes in those female slots, so I’ve ordered a $5 male end plug to hopefully keep it cleaner when stored in the lot.

https://www.amazon.com/CURT-58150-Vehic ... 175&sr=8-9

If you are looking for your Ford truck plug 12v + black (or red) wire, it’s neither...it’s orange (page 286 of 2019 Superduty owners manual). The technical reason for not following the standards might be because Ford engineers believe that orange is the new black (or red).

Thanks all for the ideas!

John
 
John, at least with my Dexter EOH unit, it called for at least a 9AH battery or bigger in the break away kit. That was a bit of a PITA to find, as most break away kits are the standard 5AH batteries. I'd be curious what that actuator draws also, but supposedly the 9AH battery is suppose to last long enough to get things stopped. I know when I tested the trailer brakes (EOH Actuator), with a tester I built, that throws the full 12vts of it's own 5AH battery, it blew the 10 amp fuse rather quickly. Like after about 2 or 3 seconds. Colby
 
I have two of the 5 amp batteries in parallel for the breakaway circuit.
Click to expand...

Hm, I may have to consider that next time! Do they each have their own box, or did you make a box to hold them both? My first kit the plastic box came from the retailer with a small crack in the bottom. Then when I mounted the replacement, there was just enough twisting torque with the box to cause another crack. I just siliconed that one, but sometime when I'm out of projects and have time I might look into going the parallel route with two batteries. A lot more choices available with the standard 5AH choices.... Colby
 
I had a similar problem with my '08 expedition, it turned out to be a missing or never installed trailer tow iso relay..hard to find on the trip but special ordered from napa and everything was fine
 
Everything is in a group 30 battery box. (Accuntuator, break away batteries etc.) Its up high so no (little) chance of getting water in it. Rain proof.
 
https://www.npr.org/sections/health-shots/2020/05/28/863526524/covid-19-has-killed-close-to-300-u-s-health-care-workers-new-data-from-cdc-shows?utm_medium=RSS&utm_campaign=news
Click to expand...

Sounds nicely done. I ended up mounting my actuator on a platform I made that raised it about 6" off the tongue. And then the break away kit is mounted higher up on the trailer's bow stop vertical frame. I may have to improve upon it all later. Colby
 
gulfcoast john":1gjr6tob said:
No 12v+ at Ford truck 7 way trailer plug mystery solved?

Hi Friends!

In Nov we dropped the trailer for EOH brake work at a reputable shop in Marathon. For $3000 many wear items were replaced, and the $1,000 Brakerite actuator. Owner upgraded the breakaway trailer battery from the 7AH mini to a U1-1 lawn tractor battery. He said the system used that battery in other ways than instances of total hitch separation, which I didn’t realize.

The new trailer brakes worked great on our return in Jan and to the Hontoon Hoot in Mar, but did not work on the back from Hontoon. All trailer lights worked fine. Troubleshooting revealed the new larger trailer battery was stone dead at 10.2v. Checking the 7 way plug, there was no voltage between the orange 12V+ and white ground pins. Confirmed that with a LED 7 way test plug.

“Your vehicle may have electrical items, such as fuses or relays, related to towing. See Fuses p 317.” Fuse #27 is for ‘Trailer tow battery charge relay (if equipped).” There was no fuse in that slot, so I added one but we’ve been towing with this truck for over a year. Also replaced # 54, “Trailer brake control module.” Cleaned and sanded the plug and applied lots of BoeShield T-9. In my experience, Boeshield T-9 can be a great substitute for understanding how electrical circuits work. No Joy.

It turns out that Ford designed this so there is no 12v+ trailer plug output unless a real trailer is connected and the truck foot brake is activated for at least 3 seconds. It’s not fooled by the 7 pin tester. Trucks like mine with a factory brake controller have a “TRM module” that controls the 12v output to the trailer battery with no fuses or relays. This is buried in a Technical Service Bulletin. The official Ford position on why this information is not in the owner's manual is “because then it wouldn’t be any fun, and girls just want to have fun.”

I replaced the dead battery with a new one, plugged in the 7 way trailer plug, hit the brakes for over 3 seconds, and the actuator pump ran. I measured 12.80V across the trailer battery at 1500 RPM with lights off (12.66 when disconnected). I would have expected 13.1v or so.

My working theory is that somehow only the 12v+ slot was dirty or corroded and that the Brakerite actuator pump was operating only off the trailer battery, which eventually discharged to dead.

I’m open to any other theory or suggestions.

I hope this can save some time and research for other Ford drivers if they run into this issue.

Happy Electrical Gremlin Chasing!
John
Click to expand...

Hi John,
Thought I'd resurrect this thread due to an issue I had with my EOH actuator this trip. I just briefly read through the other posts in the thread, which I think I already mentioned Ford's setup with the accessory pin in the towing harness only energizing when Ford's electronics recognizes a trailer is plugged in. But back on the break away battery.... I had an issue where my actuator was only actuating about every 4th time I applied my pickup's brakes. To make a long story short, I found my break away batteries (I run two 5ah batteries in parallel. I'll have to look into the larger battery you mentioned), were basically dead. Only two years old, but cheapo's. I replaced those batteries and my system started working properly again. Ok, I've always understood that the break away battery only comes into play when the break away switch is activated. (pin pulled). Guess that's not the case. I wrote to Dexter, and the next day got this back in an email:

Colby,
The unit needs a full 12 volt charge to operate correctly. No the tow vehicle does not run the whole system. The brakerite is engaging with the auxiliary battery. I am send you a trouble shooting guide to explain.
Your Titan unit is outdated, the new unit are a Dexter brand, but in the future you can replace the unit through a distributor near you.
Thank You For Your Support,
Michael J. Montoya|Q A MGR
Dexter - Winchester, TN (Plant 25)
michael.montoya@dextergroup.com
cell ph 385-226-2073
1041 Baxter Lane Winchester, TN 37398, USA
fax: (931) 967-1828 | main tel: (931) 361-4336
a DexKo Global Company ■ Together is Better
 
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