Wiring

[oilman]

Having my 2006 Sienna wired to go from the 'Factory' 4-pin to a 7-pin for Brakes and 12-volt by my local Discount Hitch-Any Caveats?

Jay

[tcp]

for someone that does it often it's not especially difficult.
-Make sure the brake controller power wire from the battery has a self resetting breaker on it, not a fuse.
-Make sure the power wire is large enough (6-8gauge) to actually charge the battery in your trailer. A 10gauge wire is rated for 15 amps as a power transmitter. Not a great deal if you have a discharged RV battery.

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

-If you are pulling a large trailer with many clearance lights, the stock harness may not be adequate. The stock harness simply powers the extra (trailer) lights directly from the vehicles lamps. If the current is too high, you'll pop fuses or push the limits of the wiring harnesses in the vehicle. An isolated wiring kit can be useful in this case:

http://www.etrailer.com/Wiring/Tow%2...119190KIT.html

This kit just makes sure there is almost no extra load on the Sienna's light circuits, but just uses them as a signal to control the trailer's lights. The main current for the trailer then comes directly from the Sienna's battery.

Having my 2006 Sienna wired to go from the 'Factory' 4-pin to a 7-pin for Brakes and 12-volt by my local Discount Hitch-Any Caveats?

Jay

[icansteve]

A question though starting from the scratch.

What I confused is that do I need to install a T-connector(4-pin adapter) first?
Then install a brake controller & wiring with 7 pin adapter which can be snugged in with 4-pin connector?

or just brake controller & 7 pin adapter are enough?
(I doubt this case since no indicator lights work)

What I understand so far is that

1. Install 2" Class-III hitch
2. Install T-connector with 4 pin
3. Brake controller & wiring with 7 pin adapter
4. Air bag(Optional)

Is this correct?

[brian_bp]

Is this correct?

Yes, some sort of wiring harness and converter is required to connect to the Sienna's lighting circuits and produce outputs to run the trailer lights, in addition to the wiring for the brake controller. While these converters normally have a 4-pin output connector attached, it can be plugged into a 4-pin-to-7-pin adapter, or just cut off and the wires attached to a 7-pin socket.

[oilman]

I took the van to the hitch shop for the wiring today, but ended up leaving without doing it as the Installer was insistent that I didn't need a Circuit Breaker for the Prodigy and a Fuse was enough. After all of the good advice I've gotten around here, I went with my instinct and left. SO-I figure I can do it myself. Can someone confirm that this http://www.etrailer.com/Brake-Contro...ler/ETBC7.html is the Wiring Kit I'll need to go from my existing 4-Pin to a 7-Pin with Brake Controller?

Thanks to everyone for their help.


Jay

[brian_bp]

I took the van to the hitch shop for the wiring today, but ended up leaving without doing it as the Installer was insistent that I didn't need a Circuit Breaker for the Prodigy and a Fuse was enough.

Sure, a fuse is enough if you are okay with losing the brakes after any momentary overload until you can stop (ironic, that part...) and replace the fuse.

You could have the shop do the job, as long as they use an ATO blade-type fuse, then replace the fuse with a circuit breaker of the same format.

Can someone confirm that this http://www.etrailer.com/Brake-Contro...ler/ETBC7.html is the Wiring Kit I'll need to go from my existing 4-Pin to a 7-Pin with Brake Controller?

I can't tell how much wire is there, and it appears to be all one colour (it is easier to work in a system in which the wires can be distinguished by colour coding), but other than that it seems like the right pile of stuff, assuming that the brake controller itself comes with appropriate wires.

This kit appears to contain:

• 10 gauge wire (but how much, in what colours?)
• 4-way to 7-way adapter
• mounting bracket and bolts for 7-way socket
• splice and ring crimp-on connectors to terminate wires
• wire ties
• protective cover for wires
• circuit breakers (one for charge power, one for brake controller power... what's the third one for?)

I didn't buy a kit - all that stuff is readily available individually - but the kit approach might be easiest.

[tcp]

You could have the shop do the job, as long as they use an ATO blade-type fuse, then replace the fuse with a circuit breaker of the same format.

Something like this would be an easy replacement:

http://www.alliedelec.com/search/pro...px?SKU=6770399

[oilman]

I watched the Install video for the 2008 Caravan. It looks pretty straightforward, but I don't see the T-tap connector they used to connect to the Brake Switch in the kit.

[brian_bp]

I watched the Install video for the 2008 Caravan. It looks pretty straightforward, but I don't see the T-tap connector they used to connect to the Brake Switch in the kit.

Good point, but to me that falls in the category of wiring associated with the brake controller itself. In the Sienna, the controller installation does require some means of tapping into brake wiring, since there is no pre-wiring provided by Toyota. I think I used a connector supplied with the controller.

[brian_bp]

You could have the shop do the job, as long as they use an ATO blade-type fuse, then replace the fuse with a circuit breaker of the same format.

Something like this would be an easy replacement:

http://www.alliedelec.com/search/pro...px?SKU=6770399

Yes, that's what I was thinking.

[oilman]

I watched the Install video for the 2008 Caravan. It looks pretty straightforward, but I don't see the T-tap connector they used to connect to the Brake Switch in the kit.

Good point, but to me that falls in the category of wiring associated with the brake controller itself. In the Sienna, the controller installation does require some means of tapping into brake wiring, since there is no pre-wiring provided by Toyota. I think I used a connector supplied with the controller.

Ah, that does make sense-Thanks

Any thoughts on installing a Relay to prevent Battery drain while the vehicle is off? I can see the utility, but is it a necessity?

[brian_bp]

Any thoughts on installing a Relay to prevent Battery drain while the vehicle is off? I can see the utility, but is it a necessity?

It is only necessary if you want to be able to leave a trailer connected to the Sienna while the engine is not running (e.g. parked) without risking running down the Sienna battery. We tow our travel trailer with the refrigerator running on 12V, and if we did not have a relay we would need to turn off the refrigerator (or unplug the cable to the Sienna) when stopping for any significant time to avoid problems (typical RV refrigerators use too much power to practically run from either tug or trailer battery).

As I understand information posted in other forums, vehicles with built-in trailer prewiring routinely include this type of automatic shut-off functionality, so the manufacturers apparently believe that it is worth the cost of the extra hardware. Unfortunately, Toyota chose not to prepare the Sienna's electrical system in any way for towing.

[oilman]

Thanks Brian-Any pointers or how to's on installing one? I know-I'm full of questions!

[brian_bp]

Any pointers or how to's on installing one?

One... brake controller?

There are two general types of controller

timed

• cheap junk which applies some braking power in some timed without regard to how hard the vehicle is braking
• these can be installed in any position as long as the manual lever/knob can be safely reached by the driver
• I wouldn't waste my time installing one or consider the rig safe using one for any trailer which requires brakes

proportional

• modern controller which applied braking power in proportion to the braking effort or deceleration of the tow vehicle
• one design (Jordan) is linked by a mechanical cable to the brake pedal - there would be few choices in mounting this
• one design includes a pad which is mounted on the brake pedal and measures the force applied by the driver's foot
• one design taps into the tug's hydraulic brake line to measure the force applied by the driver - the controller would need to mount within reach, and a pressure sensor would need to be mounted
• the vast majority measure deceleration with a pendulum or electronic sensor, so they must be mounted within reach but also pointing straight forward, not tilted side-to-side, and within some specific angle of level front-to-back

Regardless of the design, all require four electrical connections:

• power - from battery positive via auto-reset circuit breaker
• ground - from battery negative
• brake light input - from tap into wire from brake pedal switch
• output - as direct as possible to 7-way connector

The input wire carries a signal of very little current, so it can be small-gauge wire; conventionally, it is insulated in red. Someone can post the correct pin of the brake pedal switch to which the desired wire is attached, or I can crawl in and have a look later.

The other wires carry substantial current, so they need relatively heavy-gauge wire; the controller installation instructions normally specify minimum gauges. No Sienna is likely to be towing a trailer with more than 2 axles (4 brakes), so the output wire gauge requirement will not be the most extreme case in the specifications; each trailer brake (wheel) uses about 4 amps maximum.

Wire insulation colour codes for brake controllers tend to follow trailer practices (black=positive/power, white=negative/ground), rather than the 12V power and battery convention (red=positive/power, black=negative/ground). Never assume that the colour of a wire means anything without checking it specifically. The Sienna doesn't use a red positive cable, but it does have a red positive battery terminal cover.

The remaining issues are physically mounting the controller (see the other topic), and routing wires including getting them through the body in various places. We probably have a few topics on that already.

[brian_bp]

More detailed discussion of specific wiring issues:
Power (trailer battery charge) connection

• RV 12V power wire
• 7 pin wiring harness for 2006 Sienna
• how to wire a brake controller

trailer lighting - converters and load issues

• 7 pin wiring harness for 2006 Sienna
• Wiring questions

Brake controller mounting, wiring and wire routing

• how to wire a brake controller
• Is $170 for hooking up wiring to trailer okay?