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Posted by: jaybeecon55
I don't know about the Fords, but a Chevy has an aux power through through the trailer hookup that requires a fuse. In the GM truck, it's a 40 amp fuse labeled Aux Trailer. The fuse comes with the truck, but is not installed in the holder. I'd just take a look at your book - look under aux trailer lights.
Jaybee
Posted by: jaybeecon55
If you look at the seven pin connector on your truck, the pin in the 1 0'clock position is set up for 12v power to the trailer. If the truck is hooked up for this, you should be able to read 12v between this pin and ground - doesn't matter if the truck is running or if it's off. If you don't get 12v here than either there is a fuse blown or missing or your truck was never wired for the 12v aux power. Either find the fuse and install or run a hot line from the battery, through an in-line fuse back to this pin on the connector. If you do have to run a new wire, it needs to be a heavier guage - 12 ga or 10 ga should work. In addition to getting interior lights on your trailer, this should also charge up the small breakaway battery for the electric brakes.
My '96 GMC did not have this wire, even though it did have a 7-pin connector. My '02 did have the wire, but needed the fuse plugged in to work.
Jaybee
Posted by: jaybeecon55
If you are getting 12v at that 1 0'clock pin then it's not your truck. Could be that the trailer is not wired for aux up to the connector, an additional fuse on the trailer or a broken wire or poor connection causing a bad curcuit. Since the trailer is new, why don't you check back with the dealer to see if they can help you troubleshoot.
Posted by: 20045SP500HO
Some of the newer fords with the prewired plugs ... the truck must be running to power the interior lights.
Posted by: buck183
Quote
Originally posted by: jaybeecon55
If you look at the seven pin connector on your truck, the pin in the 1 0'clock position is set up for 12v power to the trailer. If the truck is hooked up for this, you should be able to read 12v between this pin and ground - doesn't matter if the truck is running or if it's off. If you don't get 12v here than either there is a fuse blown or missing or your truck was never wired for the 12v aux power. Either find the fuse and install or run a hot line from the battery, through an in-line fuse back to this pin on the connector. If you do have to run a new wire, it needs to be a heavier guage - 12 ga or 10 ga should work. In addition to getting interior lights on your trailer, this should also charge up the small breakaway battery for the electric brakes.
My '96 GMC did not have this wire, even though it did have a 7-pin connector. My '02 did have the wire, but needed the fuse plugged in to work.
Jaybee
It will matter if it's running or not. The Ford trucks are not wired constant hot with the key off. The key has to be on for a Ford to have power to the plug. GM and Dodge stay hot with or without key on.
All the SuperDuty trucks since they came out in 1999 have been like this.
I would like to know the exact year of the truck. He said it was a Stroker so it's obvious it's a Ford. If he could give a little more info and can tell him what to look for.
Buck
Posted by: JeffinTD
Are you using one of the 7 place RV style plugs (with the rectangular looking contacts) or one of the 6 way ones (with round contacts)? I presume since it has a break away battery that the trailer has electric brakes. Does the truck have a brake controller?
If it's one of the 6 place ones, not all older trailers were wired to the same standard as far as what position provided what function, and trucks were often set up to match however the trailer was wired. If that's the case, it might be a matter of using a volt meter to figure out what's what, and if something's not standard (like trailer battery charging and trailer brake position reversed) it would just be a matter of swapping wires around on the socket.
If that's not it, I would presume there's no positive power at the trailer plug. Does the truck have the factory tow package, or is aftermarket?
In either case, there should be a fuse for trailer power somewhere. I'd begin by checking for power with a volt meter on both sides of the fuse. I think Fords of that era also have a relay somewhere to provide power to the trailer only when the truck is running. I'd check that, too.
Lastly, is there a battery isolator installed in the truck? If so, check that too...
Also, I presume the battery for the break-away system is also not getting charged?
Posted by: JeffinTD
Thanks for the extra info.
Did you try taking voltage readings on all the pins on the truck, with the key on? If any of them are hot, perhaps the hot one is in the wrong location?
I don't think I have a manual that coves your particular truck. I think I'd go over to the diesel stop and run some searches or post the question.
The other possible suggestion would be to follow the wiring back from the plug, to see where it goes and where it's fused, and take voltage readings anywhere there's a junction.
A battery isolator is a device sometimes installed on rigs that tow or use a camper. It directs charging voltage from the alternator to the truck's starting batteries first, and once they are up to fully charged it will then direct power to the trailer plug to charge the batteries in the camper or trailer (which would also run the lights).
They are ofen a small metal box with heat sink fins and several large wires hooked up... Did you buy the truck new, or could a previous owner have installed an isolator?
Posted by: JeffinTD
That's really strange. I wonder why that wire would stop?
Anyhow, if you run a new wire, be sure to use a big fuse or resettable circuit breaker, and a heavy wire. I suppose you could run it straight to the battery, or to whatever lug the battery cable bolts to (to avoid corrosion).
Diesel pickups are often set up with two batteries, but they are just two normal 12 volt starting batteries in parallel (positive wired to positive and negative wired to negative).
The only drawback to having power to the trailer plug all the time is that if you park with a camp trailer, using the trailer's electric system would draw down the truck's batteries. Starting batteries don't last long if deep cycled, plus if you ran the batteries down too far...
My Dodge is wired that way factory (power hot all the time), so I just unplug the 5th wheel once I'm parked at camp. Some people add an isolator, or add a relay so the plug is only hot with key on, but for me it's just as simple to pull the plug when I don't want the trailer drawing from the truck's electrical system.
Posted by: HondaMechanic
none
Posted by: scottphillips88
Hello again. We picked up our new 21 foot interstate trailer on saturday but have one question. How do you make the two interior lights turn on? They don't come on even when hooked up to our truck. The brake/cargo lights work but not interior lights. The trailer has a battery for the emergency brakes but that's it. Do we need to buy a battery for the trailer too??
p.s. The Stroker laughs at the trailer...can't even tell it's there.
Posted by: scottphillips88
The truck was running when I tried the interior lights. Neither of the lights are burned out. I will try to look for a fuse tomorrow morning. Any other ideas? How would I connect a batter to this trailer if I didn't want to be connected to my truck for lights?
Posted by: scottphillips88
The truck is a 1997 F-250 heavy duty powerstroke. I checked the 7 pin connector, and it is wired. I also checked in my fuse box and all the fuses are used and not blown. There is not a seperate trailer aux place. This truck was used for construction so I know that the plug on the truck is wired for everything possible. I'm really confused about this one... It would really be nice to have inside trailer lights. Any other suggestions??
Posted by: scottphillips88
Thanks for the suggestion, I will check the 1 o'clock pin as soon as I get a chance. As far as talking to the dealer...well he is a retard, that's how we got the trailer for $2,000 off! He is not very bright.....
Posted by: scottphillips88
Hey guys, kind of an old topic but I'm just getting the time to fix this problem once and for all. I hooked my friends 97 dodge up to my trailer and the interior lights worked! However my friends 2001 chevy and my 97 ford still don't power up the lights. Does anyone have an owners manual for a 97 Heavy Duty? I want to know if this is a simple fuse issue before I run an intire power line.
If it comes down to this, how do I run a power line? I'm thinking of taking the truck to a local trailer shop and having them look at it. Thanks in advance
Posted by: scottphillips88
First off, I must say you guys are all very helpful and full of knowledge. Thank you for your concern with my trailer. Now I'll answer some of your questions...
It IS a 7 place RV plug.
The trailer HAS electric brakes and we DO have a brake controller in the truck.
Factory tow package.....I went to the dealership and got a wiring diagram. The colors on the diagram were different then those on the truck.
I don't know what a batter isolator is.
So, I bought a new 7 pin plug for the truck because the old one was...well old and rusty...I pulled the old plug apart and there was 7 wires going in to it. I then replaced all seven into the new plug. I figured with all seven wires going into a brand new plug that it would work fine....Wrong....every single thing works (brakes, running lights, turn signles etc.) except for the interior lights......My friends truck will power the interior lights.... Where the crap is a fuse that could fix this problem???? I'm still optimistic. Thanks in advance for your opinions.
Posted by: scottphillips88
Ok, I'm going to check the voltage on all the pins as soon as I get out of school today. Hopefully one of them is hot... The previous owner of the truck was the owner of a big construction company (Whitaker Const.) He never carried a camper, but towed very large trailers amost daily. (I'm now over 300,000 with orig. everything!!) He did have a C.B. Radio and a company radio installed....maybe they stole power from there. I'm also wondering if a diesel is different because it has two batteries. I really hate electrical. Thanks for the quick response...I'll keep you updated.
Posted by: scottphillips88
*Update* I checked all 7 plugs and no power. I know for sure now that I need constant power on the 1'oclock pin. All wires coming out of the plug are kind of thin except a blue one (trailer brakes) and orange/coral (1'oclock). For some stupid reason the orange/coral plug stops/dissapears just past the spair tire. (the blue continues)
I am going to run brand new wire and attach it to the ending point of the orange/coral wire. This should now once and for all solve the problem.
One question: where should I start the new wire?? I want it to have constant power.
Posted by: scottphillips88
*Update* After all this fuss I must say that I am a retard. When it was suggested that I look for blown fuses I looked under the steering wheel at that fuse box. All was well. However, I remembered seeing a fuse box under the hood. I found a freaking huge 30Amp fuse blown in there. Replaced it for $3 and viola it works...only when the key is in the ON position. I then pulled the crap out of my wires and found that the wire does indeed continue and ends up in a relay box under the hood. Problem Solved. Thanks Everyone.
