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Discussion Starter · #1 ·
I would like to start off by saying thanks to everyone on this site. I've been reading through these posts for quite some time (drove my wife crazy :-\) and have learned a great deal . We own a 2008 Sienna LE with the tow prep package (for sure ;D). We just purchased a "leftover" new 2008 Fleetwood Bayside this week. I would like to ask a few questions about getting the van tow ready...mainly wiring questions. I think I have most of the answers but I would like to confirm before ordering everything. Plus I thought it would be helpful for newbies like me if ALL of this info was in one thread for future references. I realize my choices aren't required so much as the recommended or popular choices from others who have posted with campers of similar weight/size. Which by the way is Dry weight 2630lbs./GVWR 3500lbs./Hitch Weight 190lbs. for the Bayside. So here goes...

1. Purchased and installed Airlift 1000 air bags (not a necessity for towing but helps with sag).
2. Purchased and installed a Curt 13256 receiver, gross trailer rate of 3500lbs. (350lbs. tongue).
3. Purchasing the Reese Mini 350 WDH (etrailer part 66041) for Fleetwood trailers with swing up jacks.
Question number one is will I need to purchase a shank? or will this WDH come with one that should fit the Sienna's height? or will I not know if it works until I try to install it on the camper?

4. Purchasing the Tekonsha Prodigy Brake Controller-Proportional (etrailer part 90185).
Do I NEED to get the Brake Controller 7+4 Way Installation Kit-10gauge (etrailer part ETBC7) in order to install the brake controller? Does this kit just make it easier to install the controller along with adding the 4-pin and 7-pin availability?

5. Purchasing the T-One Vehicle Wiring Harness (etrailer part 118304)

6. Purchasing the Upgraded Modulite Circuit Protected Vehicle Wiring Harness with 4-pole trailer connector (etrailer part 19176). I think I understand that this powered converter is needed due to the added power used to run the camper's lights (and maybe something else). And that this Modulite will need power from the van's battery via a 12V line with a circuit breaker on it somewhere near the battery.

This is where it gets murky for me. I learned from Zero260 (I believe) that once the T-one harness is installed by connecting to the tail lights of the van, that I can cut off the converter that is on the T-one harness and splice in the Upgraded Modulite Harness. If I use this method is the Modulite Installation Wiring Kit (etrailer part 118151) even needed?

So most of that all makes sense to me. But then does the 4-pole coming off of the Modulite harness get plugged into the 4-pole of the ETBC7?

The diagram of the ETBC7 also has me confused a bit. There is a wire designated "Connect to Battery With Fuse or Breaker for 12V Power Source". Is that the power for the Controller itself? So there isn't a wire from the controller that will be in the cab directly to the battery? The power for the controller comes from the van's battery all the way back to the Kit and then back to the controller in the cab?

There is also a wire designated "Auxillary Wire for 12V Power,Reverse lights...." Is that in order to have the ability to "charge" the battery on the camper while my van is running? So I will need a 12V line with circuit breaker from the van's battery to that wire?

I'm sure I'm missing something in here but I have to stop typing or I might get kicked out! I appreciate any and all input and want to thank everyone for taking the time to read this extremely long post. :eek:
 

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johnson said:
4. Purchasing the Tekonsha Prodigy Brake Controller-Proportional (etrailer part 90185).
Do I NEED to get the Brake Controller 7+4 Way Installation Kit-10gauge (etrailer part ETBC7) in order to install the brake controller? Does this kit just make it easier to install the controller along with adding the 4-pin and 7-pin availability?
Yes, this is just a convenience package with approximately the right parts which are likely required.

johnson said:
The diagram of the ETBC7 also has me confused a bit. There is a wire designated "Connect to Battery With Fuse or Breaker for 12V Power Source". Is that the power for the Controller itself?
No, that is the power source for the trailer, to charge its battery or run stuff such as the refrigerator while driving.

I assume that by "diagram" we are discussing the labeled photo on the eTrailer page for the kit.

johnson said:
So there isn't a wire from the controller that will be in the cab directly to the battery?
Yes, the controller needs a connection to the battery. I believe that eTrailer expects you to use some of the 10 ga wire, one of the circuit breakers, one of the ring terminals, and one of the splice connectors to set this up.

johnson said:
The power for the controller comes from the van's battery all the way back to the Kit and then back to the controller in the cab?
No, the kit isn't anywhere in particular; it is a collection of parts to use where they are needed. The 7-way socket is at the back, of course, but the power from battery to brake controller does not go through this socket.

johnson said:
There is also a wire designated "Auxillary Wire for 12V Power,Reverse lights...." Is that in order to have the ability to "charge" the battery on the camper while my van is running? So I will need a 12V line with circuit breaker from the van's battery to that wire?
That's a somewhat unfortunate label, as few people would use the aux connection (the centre pin of the socket, with attached yellow wire) as a simple 12V power source. It is normally used for a dedicated stop (brake) light, or for reverse lights (which can be used to lockout a hydraulic surge brake system to allow the trailer to be pushed backwards). It truly is an "auxiliary" connection, meaning it is for whatever additional function you choose.... but the tug and trailer need to agree!

The line with circuit breaker from the van's battery to supply the trailer connects to the wire of the socket labeled "Connect to Battery With Fuse or Breaker for 12V Power Source". Most of us chose to also put a relay (or "solenoid") in this line to cut it off when the van's engine is not running, to avoid accidentally running down the van's battery. The eTrailer kit does not include this relay.
 

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johnson said:
6. Purchasing the Upgraded Modulite Circuit Protected Vehicle Wiring Harness with 4-pole trailer connector (etrailer part 19176). I think I understand that this powered converter is needed due to the added power used to run the camper's lights (and maybe something else).
Yes, but it's just for the lights.

johnson said:
And that this Modulite will need power from the van's battery via a 12V line with a circuit breaker on it somewhere near the battery.
Kit 118151 is another convenient collection of wiring bits to get power from the battery to the powered Modulite module.

johnson said:
This is where it gets murky for me. I learned from Zero260 (I believe) that once the T-one harness is installed by connecting to the tail lights of the van, that I can cut off the converter that is on the T-one harness and splice in the Upgraded Modulite Harness.
Correct - the harness which is specific to the Sienna is used to easily plug-in to the Sienna's wiring, and the converter that comes attached to that harness is not used if the powered Modulite converter (19176) is used instead.

johnson said:
If I use this method is the Modulite Installation Wiring Kit (etrailer part 118151) even needed?
The 118151 installation kit, or similar parts, is required, regardless of how the Modulite module connects to the harness of wiring from the Sienna's lights.

eTrailer's Upgraded Circuit Protected Modulite with 4 Pole Harness and Hardwire Kit - Includes Testers (119176KIT) is the powered Modulite converter (19176, the installation kit (118151) for power, a tester, and some tap connectors that would not be used by someone who is using T-One (or similar) harness. It doesn't save any money, unless the tester and tap connectors are worth more than $5 to you.
 

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Discussion Starter · #4 ·
thanks for all the great info brian_bp. I just received my shipment from etrailer yesterday. I have to admit it appears to be somewhat of a daunting task for someone who has never done this before (--->this guy<---). It might be some time before I actually get going on it...but I'd better get it done by the end of the month or I'll be pushing my pup to the CG.
 

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One step at a time and it will all come together. Start by bolting the receiver onto the van. Then add the airbags. Wiring is it's own joy :-\, but one step at a time there and it'll all work. ask when you run into something that you can't figure out.


johnson said:
thanks for all the great info brian_bp. I just received my shipment from etrailer yesterday. I have to admit it appears to be somewhat of a daunting task for someone who has never done this before (--->this guy<---). It might be some time before I actually get going on it...but I'd better get it done by the end of the month or I'll be pushing my pup to the CG.
 

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Discussion Starter · #6 ·
thanks for the words of encouragement tcp. So I've come up with a few more specific questions...
1. For the brake controller power from the van's battery what gauge should be used and will it need to be "stepped down" to a smaller gauge to fit the wire coming from the controller itself? Also what size should the self-resetting circuit breaker be for this power run?
2. For the power to the modulite from the van's battery what gauge should be used and will it need to be "stepped down" to a smaller gauge to fit the wire coming from the modulite? Also what size circuit breaker?
3. and you guessed it...For the power to go to the 7-pin for charging the camper's battery what gauge should be used and will it need to be "stepped down" to fit the wiring for the 7-pin? What size circuit breaker? And what size (?) relay should be used if I do get one?
 

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johnson said:
thanks for the words of encouragement tcp. So I've come up with a few more specific questions...
1. For the brake controller power from the van's battery what gauge should be used and will it need to be "stepped down" to a smaller gauge to fit the wire coming from the controller itself? Also what size should the self-resetting circuit breaker be for this power run?

Each electric trailer brake uses a 3-4amps at full voltage. If your trailer is single axle, that's about 6amps and if it's dual axle its about 12 amps. A 10gauge wire from the battery should be fine in either case. The controller power wire is either 10 or 12 gauge so connecting the two shouldn't be a problem. I figure the only time I want the brakes to stop working is on a dead short so even with my single axle trailer I use a 30amp breaker. 20 would be fine. 10 may cause problems with inrush current.

2. For the power to the modulite from the van's battery what gauge should be used and will it need to be "stepped down" to a smaller gauge to fit the wire coming from the modulite? Also what size circuit breaker?

This again varies with the number of running lights your trailer has. The modulite will draw the amount that is pulled by all running lights being on as well as brakes depressed. Honestly, for lights, a 10gauge or even 12gauge would be fine as a bit of voltage drop along the run isn't going to effect the lamp's light output in any considerable way. I would go with 30amp again as your only real concern is a dead short.

3. and you guessed it...For the power to go to the 7-pin for charging the camper's battery what gauge should be used and will it need to be "stepped down" to fit the wiring for the 7-pin? What size circuit breaker? And what size (?) relay should be used if I do get one?

This one gets a bit more murky. I have a dual 10gauge wires run for this and after a few trips out I realized that I don't actually charge my batteries in any considerable way while driving. I "maintain" or add a bit of surface charge, but no real charging seems to occur. I would go with a minimum of 8 gauge for this run. Chances are good you're never going to charge at any rate over 30 amps while driving even with a 8 or 6gauge wire run so the breaker and relay should be rated for about that: 30 amps. I have a bank of 3 batteries that I have installed in our trailer (I use a big inverter to run the microwave from the batteries). Even the regular automotive relays are good for 30amps switched and 40 amps with the contact made:

http://www.the12volt.com/relays/relays.asp

It's the long runs of wire that drop voltage, not the relay contacts unless they get old, oxidized or dirty.


As far as splicing wires, if you have any experience with a soldering iron, soldered and heat-shrunk connections are the best. You can push the strands of each wire into each other and coat the whole thing with solder (make sure it flows into the strands and doesn't just blob on top) or do it the "proper" way:

http://w6rec.com/duane/bmw/solder/

either way is better than a crimped connection.
 

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tcp said:
This again varies with the number of running lights your trailer has. The modulite will draw the amount that is pulled by all running lights being on as well as brakes depressed. Honestly, for lights, a 10gauge or even 12gauge would be fine as a bit of voltage drop along the run isn't going to effect the lamp's light output in any considerable way. I would go with 30amp again as your only real concern is a dead short.
I agree, except that I would match the breaker more closely to the wire. 12 gauge is enough for the purpose, but if using 12 gauge I would limit the breaker to 20 amps.
 

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Discussion Starter · #9 ·
this is perfect! one more...
For the output wire from the brake controller back to the 7-pin...what gauge wire should be used and is anything needed with it (fuse/circuit breaker/relay)?
thanks again guys!
 

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no fuse required and 12gauge is probably fine for a single axle. Dual axle I would use 10 gauge but even that might be overkill. The common color for this wire is blue.

johnson said:
this is perfect! one more...
For the output wire from the brake controller back to the 7-pin...what gauge wire should be used and is anything needed with it (fuse/circuit breaker/relay)?
thanks again guys!
 

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johnson said:
For the output wire from the brake controller back to the 7-pin...what gauge wire should be used and is anything needed with it (fuse/circuit breaker/relay)?
I noted that the Tekonsha generic brake control wiring instructions (which I have attached, because I no longer see them as a separate document on the Tekonsha website, although it is page B-2 of the 2008 Catalog) specify:
CAUTION Use of proper gauge wire when installing the brake control is CRITICAL; smaller gauge wire may result in less than efficient braking. Minimum wire gauges are as follows:
• 1-2 axle applications - 14 GA.
• 3-4 axle applications – 12 GA.
Accordingly, I used 12 gauge wiring in the Sienna - with blue insulation as per common practice to be easy to follow - so that the wiring would not limit what I could tow. Although this is the minimum for 3 to 4 axles, it leaves a significant margin for any trailer which I might actually tow, which would have no more than two axles; it is perhaps overkill for the trailers which I expect to actually tow, which have a single axle.

Within my trailer, the cable from the plug to the wiring termination box includes a 12-ga blue conductor as per industry standards. From there to the brakes I used a rubber-jacketed two-conductor cable which happens to have black and white conductor insulation (I used black for brake power and white for return); this cable is only 14 gauge, but I know it is only supporting a single axle, since that's all the trailer has... again, a generous size.

The Tekonsha guide shows no circuit overload protection (such as a breaker) in this circuit, and I believe that the breaker in the power supply to the controller appropriately protects the output wire from overload, so I agree that there should be no breaker in this line. Fewer components means less chance of failure.

My typical controller setting for towing my travel trailer is "7", meaning 7 volts applied at full braking. That means that each brake will never get as much as two amps, so all of this wiring has far more than required capacity.
 

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johnson said:
1. For the brake controller power from the van's battery what gauge should be used and will it need to be "stepped down" to a smaller gauge to fit the wire coming from the controller itself? Also what size should the self-resetting circuit breaker be for this power run?
Again from the Tekonsha guide quoted and attached above...
Connect BLACK (+) wire through an automatic reset circuit breaker (20 amp for 1-2 axles, 30 amp for 3-4 axles) to the POSITIVE (+) terminal of the battery. The BLACK wire is the power supply line to the brake control.
I used a 20 amp breaker and (I think) 10 gauge wire; I think that the controller's wire was smaller, but within the range which was accommodated by the same size of crimp-on butt connector.

Again, this power supply capacity is far more than the controller will need in actual use with my current trailer, and at least adequate for anything I will tow with the Sienna.
 

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Discussion Starter · #13 ·
from my question about powering the "charge" line you replied....
This one gets a bit more murky. I have a dual 10gauge wires run for this and after a few trips out I realized that I don't actually charge my batteries in any considerable way while driving. I "maintain" or add a bit of surface charge, but no real charging seems to occur. I would go with a minimum of 8 gauge for this run. Chances are good you're never going to charge at any rate over 30 amps while driving even with a 8 or 6gauge wire run so the breaker and relay should be rated for about that: 30 amps. I have a bank of 3 batteries that I have installed in our trailer (I use a big inverter to run the microwave from the batteries). Even the regular automotive relays are good for 30amps switched and 40 amps with the contact made:
So if I run 8 gauge with a 30amp auto-reset circuit breaker and 30 amp automotive relay for this connection...can the 8 gauge wire be soldered directly to the appropriate connection wire labeled "Connect to Battery With Fuse or Breaker for 12V Power Source" on the 7-pin harness?
 

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Sure. Even if the wire from the harness is smaller than the 8gauge wire, you can simply solder the two together and be done with it. I would try to get as much of the 8 gauge directly from the battery to the 7pin connector. Try to keep lesser gauge wires to the ends or near connections. There are different capacities for wiring depending if they are for power transfer or in a chassis(short lengths):

http://www.powerstream.com/Wire_Size.htm

I spend my days designing circuits and writing code to run them so I tend to gloss over things that seem natural and I've seen many times. Keep asking until it makes sense to you. My entire wiring was done from scratch and I designed my control/fanout circuit(your modulite) to work with 55amp FETs (field effect transistors) switched by the light circuits. I have no extra load on my lights and everything is powered from the battery by a 6 gauge welding cable (heavy neoprene jacket, very fine stranded wire), through a 70 amp maxifuse and then breaks out to the light control circuit, relay for power and another branch for the brake controller. I wish I had more time to play with this but it seems to all be working so I can't.

johnson said:
from my question about powering the "charge" line you replied....
This one gets a bit more murky. I have a dual 10gauge wires run for this and after a few trips out I realized that I don't actually charge my batteries in any considerable way while driving. I "maintain" or add a bit of surface charge, but no real charging seems to occur. I would go with a minimum of 8 gauge for this run. Chances are good you're never going to charge at any rate over 30 amps while driving even with a 8 or 6gauge wire run so the breaker and relay should be rated for about that: 30 amps. I have a bank of 3 batteries that I have installed in our trailer (I use a big inverter to run the microwave from the batteries). Even the regular automotive relays are good for 30amps switched and 40 amps with the contact made:
So if I run 8 gauge with a 30amp auto-reset circuit breaker and 30 amp automotive relay for this connection...can the 8 gauge wire be soldered directly to the appropriate connection wire labeled "Connect to Battery With Fuse or Breaker for 12V Power Source" on the 7-pin harness?
 

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Discussion Starter · #15 ·
so for my the entire wiring system...how many ground wires will I need, where will they run from and to, and what gauge should they be?
 

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I would suspect only two would normally be required but I assume the modulite will require an extra (or it can be grounded at the same point as the 7 way connector ground wire that runs out to the trailer plug).

One near the brake controller. This is a reference ground and will not flow any real current. The trailer brake current flows through the ground return on the 7 blade connector.

One from the 7 blade connector that comes from the socket outside. Make sure this a GOOD Ground as the brake current will flow through it along with light current and charging current clear some area to bare metal and bolt the wire to it with a ring terminal. The better this ground is, the more efficient everything else is.

One from the modulite unit. This is really just a reference ground again as the light current will return through the 7 blade connector. using the same spot as the GOOD ground from the 7 blade connector would be a smart option.


johnson said:
so for my the entire wiring system...how many ground wires will I need, where will they run from and to, and what gauge should they be?
 

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The Sienna's own electrical system - following typical automotive practice - uses some carefully selected and prepared points to connect to the body, and the steel of the body to conduct back to the battery. Added wiring can use the body through as carefully managed points - perhaps the very same points which Toyota uses... or it can use separate wires straight to the battery's negative terminal. I put in the wires.

Remember that paint and rust make for lousy connections, and that the body is painted and where you break the paint film the steel rusts.
 

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Discussion Starter · #18 ·
So if I run 8 gauge wire with 30amp cb, and 30 amp relay back to the 7-pole for 12V charging power...can I just tap into that same 8 gauge line to power the Modulite?
 

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From an electrical safety point of view, I see no problem with sharing a properly protected (right-sized breaker) circuit among as many loads as desired, provided that their total demand is not excessive for the circuit.

On the other hand, from a vehicle safety point of view, I would not want my trailer lights to stop working because of any electrical fault associated with the trailer battery and its charging supply. When the charging circuit's breaker opens because of an overload, anything sharing that power supply would stop working. I would, instead, run a separate circuit for the Modulite, with appropriately sized wire and breaker as discussed earlier.

Similarly, I would not want my trailer brakes to become non-functional due to a breaker popping in response to a short in a trailer lamp. The end result is three independent circuits, for lights, brakes, and charging. In my case, the trailer lights are powered from the Sienna's light circuits (I don't have a powered converter such as a Modulite), so I only have two circuits (brakes and charging).
 

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Discussion Starter · #20 ·
Thanks everyone for your quick and informative replies. Everything should be ready to go...with the exception of caulking the grommets in the rear well. I'll be picking up my camper tomorrow afternoon so hopefully its all installed correctly [fingers crossed].
 
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