Trailer wiring on Tow vehicle

[David Thomson]

A few of us are debating on the best wiring set-up for the tow vehicle. I have a 2001 Olds Sillhouette van with the tow equipment that can tow up to 3500lbs and I have a 13' boler with a 4 pin set-up. I will be re-wiring the boler for power from the van and am debating on back-up lights mounted on the bumper of the trailer. It has no brakes, and the van has no brake controller. I doubt I will tow much other than the boler (possibly a 17' if I ever find a decent one) but am limited by weight until we replace the van. Should I do 6 pin or 7pin on the van?

I know it is a loaded question with many different opinions.

Dave

[CD Smith]

Just purchase the 4-wire to 7-wire adapter. It has pigtails for the other wires and they are very easy to crimp onto the wires you have to add to the tow vehile.

[Charlie C]

Hi Dave, I would recommend using the 7 pin connector on your vechicle. Various adapters are much easier to find for the 7 pin, and if you ever need electric brakes, you already have the correct connection. The travel trailer industry is pretty well set on the 7 pin configuration, so even if you happen to move up to a 15' Trillium or something like that you are almost ready to go!

Once the vehicle is wired to 7 pin, you can then rewire the boler to 7 pin or get a 7 to flat 4 adapter just about anywhere. If you ever decide to replace the axle on your trailer, the price difference to get an axle with brakes is not that great, and well worth the better handling.

[Brian B-P]

Yes, I would definitely go for the 7-pin on both tow vehicle (I used an adapter to work with the factory light converter's 4-pin output) and the trailer. It is the closest to a universal configuration for anything more than basic lights, and converter connectors are available to make either 7-pin tug or 7-pin trailer work with lesser connections if you ever need to.

Dave, if you ever find that 17' you'll need the trailer brakes; you might as well get the right connector now. And Charlie has a good point: even the 13' could go to brakes. It might even need them - for legality in some states or to meet the van's limits - depending on how heavily it is loaded...

Originally posted by 2004 Toyota Sienna Owner's Manual@ page 386
If the total trailer weight exceeds 453 kg (1000 lb.), trailer brakes are required.

1000 lb to 1500 lb is a common range for trailer towing with vehicles the size of the Sienna or Sillhouette; a 13' Boler is almost always over 1000 lb when loaded, and often in the range of 1500 lb.

[Gerry]

Just purchase the 4-wire to 7-wire adapter. It has pigtails for the other wires and they are very easy to crimp onto the wires you have to add to the tow vehile.

Hi CD and rest, I got one of these 4 to 7 pin adapter plugs to replace the 4 pin trailer plug a previous owner had put onto Lady-bug my 13ft Boler. I wanted to get the extra wire lead into the camper as a charging wire for the battery.
Yes, it was an easy job and the 7 pin connector on the tow vehicle also has the standard 4 pin connector along side of the 7 pin so my other yard trailler with just a 4 pin connector still goes on.
But, when I had to deliver fire wood a few weeks ago I hooked up the 4 pin to the new TV adapter and the lights on the trailer didn't work as they should.
I haven't hooked it up to the 7 pin connector I installed on Lady-bug yet, because she is buried in the back and I can not get the truck down there so I do not know if I screwed up or if for some freakey reason the adapeter is screwed up.
All I did was mount the new TV plug, Plug in the 4 pin adapter under TV, Ground to same Ground spot on TV and run new wire to the designed pin on the 7 pin connector as the charge wire.
I see no reason why my older trailer with the 4 pin wouldn't work but when I plug in the camper next spring it will be interesting to find out if this works.
Gerry

[CD Smith]

The adapter is only wire and contacts. I don't see how it wouldn't work unless it is defective. Even if you mis-wired the groud and power, it would only blow the fuse assiciated with the battery connection and shouln't keep the four wire from working.

I am totally perplexed!

[Gerry]

The adapter is only wire and contacts. I don't see how it wouldn't work unless it is defective. Even if you mis-wired the groud and power, it would only blow the fuse assiciated with the battery connection and shouln't keep the four wire from working.

I am totally perplexed!

Now that the Lady-bug and utility trailer are snow bound for the winter I will have to wait untill spring to get things worked out.
I just may need to get a more competent person in the back to let me know what is going on
Now that would be a real easy fix (unless the wife reads this)
Gerry

[Roger H]

Gerry & CD,

The overwhelming odds are that it's either a ground problem or corrosion. 99.9% of all trailer wiring problems (provided that they're wired properly and have all of the right leads going to the right places) are ground or corrosion or a corroded ground problem!

David,

I would recommend a Bargman-style 7 pin plug. It is the industry standard, and adapters are made for it to all others. It will allow you to tow any trailer your van is competent to pull and still be able to hook the wiring up in a matter of minutes. The six-pole plugs, while they work, only work for six pole connectors and there are very few of them in use.

Roger

[Pete Dumbleton]

I bought a 7 (TV) to 4 (Trlr) adapter the other day at Wally, but haven't plugged it in yet -- The 4 side has LEDs to let me know how stuf is behaving (one reason I bought it; I am going to help a neighbor troubleshoot/rewire his utility trailer and first thing I want to check is whether the problem is actually in his Cherokee or in the trailer). I have also seen 4 to 4 "adapters" with the LEDs for troubleshooting.

I would go with the 7-pin for likely compatibility with any trailers (someone else's or your own) that you might be pulling in the future.

[David Thomson]

I actually bought one of those 4 prong LED testers from Uhaul to make sure I wired it correctly (I bought a plug and play set up but wanted to be sure) and I according to it I had tails and no signals. Cracked out the old stick style with a light in the body and it was a bum LED tester. Moral, don't trust the LEDs completely.

I will be picking up the 4 to 7 this week and start wiring it into the van.

Thanks for all your advice guys.

[bonnie w]

Last summer when I was getting my hitch installed on my Colorado truck, I asked the mechanic to put on a seven wire plug. I did at that time mention that I would like the brakes hooked up. When I returned to pick it up he said that he had called down island to someone, and they said that I didn't need electric brakes on a tt so lightweight.

I have to admit I am totally unknowledgeable about tt wiring, but when I was parked for the night with it the 12 volts started to dim soon after. (I might add I didn't unplug from the truck when settling down for the night). If I do get a 7 prong installed the battery will charge while the truck is running - correct?

[Roger H]

If I do get a 7 prong installed the battery will charge while the truck is running - correct?

If both the truck and trailer are wired to the connector with a charge line, then your battery will charge while you tow. It sounds like your mechanic may have taken some short cuts though.

I'd be a little concerned about any mechanic who tells a customer "you don't need it" after you specifically asked for the brakes to be wired.

Roger

[james kent]

When I got my recent tow and had a hitch put on thet automatically put on a 7 pin connector. I changed from a 5 pin to a 7 pin on the trailer with no problem.
EXCEPT
When I connected the wires I got them mirror image reverse. The diagram showed them from the opposite side. Realized it when I kept popping fuses.

[Gerry]

If I do get a 7 prong installed the battery will charge while the truck is running - correct?

Yes as Roger H. says it will worked if the charging wire is hooked up from Pos post of your TV battery to Pos post of T battery.
This was the main reason I put in my Bargman 4 to 7 pin adapter.
When I got it at Wally*World I didn't even see that along side of the TV 7 pin plug was also the 4 pin plug.
This was going to work out great as myself and some friends just have utility trailers with the 4 pin connectors.
And also the easy with the plug into the existing 4 pin connector already on my truck was going to be a snap.
All I had to do was run the wire from the Pos post on Battery back to the proper pin and I soldered and crimped the wire and in theory it was done.
Let's Hope for the best and we will know more in the spring.
Gerry

[Brian B-P]

...All I had to do was run the wire from the Pos post on Battery back to the proper pin and I soldered and crimped the wire and in theory it was done...

This will work, but when the tug is not running, but the trailer is plugged in, two things happen:

• the tug battery can be run down by any power used in the trailer
• when you start the truck, some power will come from the trailer battery

Both of these are bad, which is why some sort of isolating device (a diode or relay) is normally used in the charge line. I used a relay which only turns on when my van is running (and not while cranking to start).

[Brian B-P]

...I'd be a little concerned about any mechanic who tells a customer "you don't need it" after you specifically asked for the brakes to be wired...

That's so polite. I would be steaming mad that some irresponsible jerk both ignored my instructions and provided "information" which is incorrect, and which may both case the rig to be illegal (in some jurisdictions) and potentially unsafe.

[Pete Dumbleton]

The law may say you don't require brakes on a light trailer (but in other locales the law may say something different) but that doesn't mean the brakes are not a good thing, esp if your tow vehicle is on the light side (I could really feel the difference on my 4,000+ lb truck when I put brakes on my 1,700 lb trailer, BTW).

As Roger pointed out, this guy's work should be checked... But the good part is he DIDN'T try to wire the brakes

Brian's right, BTW, about the TT battery chiming in on TV start (IF the TV battery is low); when I had a dead TV battery a long time ago, I popped the 30A fuse on the TT battery (I have since replaced it with an auto-reset 30A breaker).

[Gilles]

And Charlie has a good point: even the 13' could go to brakes. It might even need them - for legality in some states or to meet the van's limits - depending on how heavily it is loaded...
1000 lb to 1500 lb is a common range for trailer towing with vehicles the size of the Sienna or Sillhouette; a 13' Boler is almost always over 1000 lb when loaded, and often in the range of 1500 lb.[/QUOTE]

You can see it in "Trailer Brake Required" column,
on this WEB page:

State Towing Laws

[Bob Miller]

I don't think that the O.P is still reading this thread, the last entry was in 2007

[Gilles]

Originally Posted by Bob Miller

I don't think that the O.P is still reading this thread, the last entry was in 2007

Sorry. I got lost by reading various remarks.

Break.
It makes a beautiful sun and before the rain announced for tomorrow I am going to go to break the block of snow which prevents me from bringing out my caravan.

Have a good day,