DC owners with seat heaters, what fuse location is everyone using for their heaters?

For those of you who have driver and passenger side seat heaters, where are you drawing power for the heaters? Are you using one fuse location for both seats?

I am about to wire these up. I haven't done too many car eletrical projects before, so still a bit of a novice in this area. So, would love to some feedback on my line of thought here.

First, I have a double cab offroad with tow package, from what I've read, it doesn't sound like i have any powered unused fuse locations, because that would be the ideal thing to tap into.

So, I'm thinking about using an add-a-fuse in the two 7.5amp fuse locations (GAUGE and ACC) in the instrument fuse box, wiring one seat heater to each. I still have to verify that both of these spots are not always hot, too. If one is, I'll obviously not want to use that. I like the idea of using 2 separate fuse locations, so that if there's an issue with one of the seat heaters, it's more easily isolated. Also, I wouldn't be drawing too much from one location this way.

The seat heaters that I bought are 30 watts max per pad, so that would be 60 watts total per side/set, or 5amps. Am I correct in thinking that using 7.5amp fuse locations would be good ones to use, and run two 7.5 amp fuses in the add-a-fuse? At max heat, one set of seat heaters will draw 5amps, so I probably want a fuse that's the next step up (7.5amp), right?

I've seen some threads on here where people are using 10amp and 20amp locations. But, it also hasn't been clear from what I've been reading in people's write-ups if they're putting both seats on the same fuse. If so, I'm not even sure how to do that?

Am I over complicating this?

 

Thanks. That's a good idea. I'll need to look into that option a little more. My next electrical project will probably be led lights in the bed, nothing big.

But, I'm still curious as to how various members have connected their seat heaters. I'm also curious as to what fuse location factory seat heaters use. Haven't found that bit of info, either. The owner's manual doesn't seem to mention seat heaters in the fuse map diagram.

 

Well, I've seem people mention OEM seat heaters, but not very often. I don't know if it's a true OEM option, or maybe dealer installed?

Yes, that was my train of thought as well. The seat heaters I have will draw 5amps max each side, so I'm thinking of tapping into 2 separate OEM fuse locations.

Me neither, but always willing to learn! Thanks!

 

Heaters can draw a fair amount of current.
Personally, I would run a 10ga wire directly from the battery, fused at 20 amps, and run that through a 30a fog light relay. Battery in to pin 87, heaters connected to pin 30.

Using an Add-A-Circuit with a 5 amp fuse, tap into the Radio or other switched accessory circuit, and run that to the relay pin 85. Run pin 86 to ground.

When the accessory circuit is hot, the heaters will have power. When you shut the truck down, the heaters will shut off even if you leave the switch on.

 

I've got two questions regarding this.

1) Will this method still allow the switch's Hi/Low settings work? I'm unsure of how the relay will effect the amount of current the pads will receive.

2) And I assume that you just ground the pads anywhere as well as having to ground the relay?

 

In Canada there is an OEM factory heated leather seat option on the Sports and Limiteds

 

Looking at this again, where do I connect the switch to the relay?

Anything wrong with this set-up?

30 - fused power supply
85 - GND
86 - switch
87 - heater pads

 

My suggestion uses a dedicated circuit to power the seats so you are not drawing from the factory power outlet circuit.
Instead, it uses the lighter circuit or another accessory circuit to "arm" the seats... the provided high/low switch triggers the seat heaters normally:

30 - 20a fuse to battery
85 - GND
86 - 5a fuse to lighter or other switched source (radio, IGN, etc...)
87 - Switch
87a - Insulated (if present)

Heaters connect to the switch as described in the instructions.

This prevents you from leaving the heaters on after shutting the truck off, will activate the heaters from remote start if you leave the switch on (and source 86 to something that comes on when the engine starts), and prevents you from pulling too much from the power outlets, example you are running your compressor and your passenger gets a cold ass and turns on the heat.

85 and 86 are simply the relay coil contacts and can be interchanged.
30 is the switched common. 87 is the NO contact, 87a is the NC contact.

I kinda like to connect the battery to 87 and the switched item to 30, because that arrangement never applies power to 87a, but it is the reverse of conventional wiring, and as long as 87a is insulated, it doesn't really matter.

 

30a relay with a 20a fuse, you'll pass 20a before the fuse goes, just make sure you wire the thing up with #10 wire from the battery through the relay to the heater kit's fuse.
Put your 20a fuse as close to your battery as you can.

 

I think I'm confusing myself here, I don't know enough about relays or how they work.

The above method would receive power to the pads via the 20A battery wire but only with the key in the ignition?

 

Here's the factory relay...

 

Correct.

The relay is simply a switch, and the switch is operated by applying power across 85 and 86.
For fog lights, we wire the dash switch to 85 or 86 and the lights directly to 30 or 87.

For the seat heaters, we want to retain the 2 (or more) stage heat control, so instead of putting the switch on 85/86, we allow the truck to control 85/86, and we rely on the manufacturer to provide us with a switch that won't be overloaded by the seat heaters on full.

 

That makes more sense now. And in regards to 87A what do you mean by insulated?

 

Pin 30 is connected to 87a when the relay is not activated.
This means that 87a is connected to the battery any time the accessory is "off".
The pin needs to be covered so it can not short to anything nearby. Not all relays have 87a... it is the terminal in the middle of a standard fog light relay.
If you are using a socket, just slip some heat shrink over the wire that comes from the center socket. If you are not using a socket, put an insulated female connector over the pin.

 

Ahhh ok, now I understand! That diagram is a good one to have.

 

I bought a set from ebay that came with a relay installed in the wiring harness already. So it came wired for 12 volt power, ign switched power, ground, and illumination.

Most of the ebay sets I have ordered came that way with the relay already installed, one on each seat heater wiring harness.

 

I've seen some of those more recently.

The set that I bought a couple of years ago just has two complete systems... 4 heated pads, two 3-position switches, and a fuse holder.
The switches turn on pad-1 or pads 1 and 2.

I have seen some nicer units more recently that even have selectable seat/back/both and temp adjust.

 

Hey guys, sorry for the neglect on my own thread.... Rich, thank you for the info. I'm going into this with pretty basic electrical knowledge. Between the info shared in this thread and just general research, I'm starting to comprehend how it all works a bit better. For instance, I really didn't understand how a relay worked until this thread prompted me to research that more.

Also, when I originally wrote this post, I hadn't taken a close look at what came with the seat heaters that I bought. The seat heater kit I got does indeed have a relay. There are 4 wires that need to be connected:
Red - main power, has an in-line 20 amp fuse
Red/Yellow - connect to ignition on, has an in-line 5 amp fuse
Yellow - connect to headlight/night lamp. powers a bulb in the switch to illuminate it at night.
Black - ground

The kit came with a set of 2 seat heaters, with 2 pads per set. The pads each max out at 30W each.

So, I know I can run the main red wires straight to the battery and identify and tap the respective ignition and night lamp wires inside the cab for the other wires. That's the standard install for this seat heater kit.

However, I also know that once I get these seat heaters wired up, my next project will be to wire up some led lights in the bed. Beyond that, I don't have a specific list of things I'll be adding, but I do want to plan ahead around making it a non-issue to add more electrical accessories down the road. I'm open to the idea of doing a dual battery setup down the road, if I need to, too.

With that said, and I would love to hear some feedback on this part, I'm thinking of first installing this Painless aux fuse box in the engine bay. The fuse box has 4 ignition hot circuits and 3 always hot circuits. Once I have that installed, I can then wire up the seat heaters to the fuse box instead of directly to the battery. I like the idea of having all aftermarket electronics on a separate fuse box and not connecting too many things straight to the battery. Also, since this fuse box has ignition hot circuits, I actually have no need for the in-line relay on the seat heater. I like the idea of not having to tap into any additional wires if I don't need to. To that end, what I'm thinking is to connect the main power (red) wire from each seat heater to a separate 20A ignition hot circuit on the fuse box. Since the seat heater already has an in-line 20A fuse, I've now got 2 fuses on the main power line. Nothing wrong with that, just unnecessary, right?

Next, feed the ignition on (red/yellow) wires from both of the seat heaters to a third 20A ignition hot circuit on the fuse box. My understanding is that by wiring up the red/yellow wires to a separate ignition hot circuit, i'm effectively using 2 relays (one in the fuse box and one in each seat heater) to control power to the seat heaters. Again, nothing wrong with this, but unnecessary. The pros of this, to me, is that I'm not tapping into additional wires and preventing spaghetti wiring throughout the truck. The cons of this are that I'm occupying a fuse location in the aux fuse block that i might otherwise want to use for something else.

That would leave just the night lamp (yellow) wires from both of the seat heaters. I'd have to tap into the appropriate wire in the cab for those, or my other idea is to run them to the same 20A ignition hot circuit that the ignition on (red/yellow) wires would go to. The effect of this would be that the seat heater switches would always be illuminated. I don't think that would bother me, and would again save me from having to tap into another wire. The assumption here is that I can run 4 low current wires to the same 20A fuse location. The ignition on (red/yellow) wires have in-line 5A fuses, too.

So, I'm realizing there are a lot of different ways one might wire something like this up. My goal is to make things as "clean" as possible and obviously not burn down my truck, too. I'm not sure if I'm overthinking or overcomplicating this, or if this sounds like a smart way to go about this. So, any input or advice is welcome.

 

Been thinking about ordering these for over a year now. Post some pics and let us know the results. Thanks.

 

I put this same set in my wife's 2010 corolla a few months ago. They work perfectly. A great addition to the car. I didn't mount the pads in the seats. We took the seats out and used a local upholstery shop to install the four heat pads. While the seats were out being worked on, I wired the car.

I ran a fused primary wire from the battery heavy enough to power both seat heaters, and picked up ground on the firewall. I put the accessory power wires together on one fuse tap and wired the illumination circuit to the green wire off of the A/C panel.

Works very well, particularly since we are in the great white north!