How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 47953
Experience:  16 years experience
Type Your Ford Question Here...
Chris (aka- Moose) is online now
A new question is answered every 9 seconds

2003 Ford Explorer XLT: wiring diagram..factory..fuse box is tucked

This answer was rated:

2003 Ford Explorer XLT
I need to wire in an after market seat heater. The wiring diagram shows fuse 2 as the factory seat heater circuit. The fuse box is tucked up under the dash. How do I get to fuse 2 with my wires?

Hello Andy


I'm Chris, Thanks for allowing me to help you here on Just Answer.


To route wires from the seat to under the dash you need to remove the seat. Do this by unplugging all the electrical connections under the seat then remove the 4 nuts/bolts holding the seat frame to the floor. Then remove the door sill plate (this is the plastic cover which is the first thing you step on when you enter the vehicle) Its held down by push clips which you just pry up on to remove. Now route your wire under the carpet and along this sill plate and in behind the kickpanel to the fuse panel

Customer: replied 7 years ago.
I am past that part. I have already put the seat heater pads in the seat and have routed the wire up through the center counsel where I have to install the switch. The wires are now under the dash at the fuse box. I need to know how to access fuse 2 for power and where to ground to.
You ground it anywhere. Just sand a bare spot on the chassis and use a electrical eye and bolt or screw it to the chassis for a ground. As for wireing into fuse 2 swing by your local parts store and buy a fuse which allows for a wire connection. Its a normal fuse but it has a wire extension off the fuse side to connect another wire to. Or you can just place the wire in beside the fuse on the fused side and just insert the fuse.
Customer: replied 7 years ago.
The wiring harness already has a fuse in the line so I don't need to go to the parts store. I just need power. I was going to use both fuses as extra protection.

You say to strip the end of the wire, pull the fuse, insert the wire into the socket and push the fuse back in? How do I know which side is the fused side. Also, have two wires - one for each seat. Can I put both wires in one socket or should I splice them into one and out just one in the socket?
What is the fuse rating which is inline. What turns this heater off and on?
Customer: replied 7 years ago.
The fuses are 10a. Fuse 2 on the Ford is 20A. The harness has an on/off switch in it with three settings -off, low, high. The circuit also has a control that automatically turns the heater off after 30 minutes (I think).
In this case in may be best just to go ahead and route the wire all way to the battery and connect it there since you already have a inline fuse for circuit protection rather than pushing wires into the fuse panel and kind of rigging it. To determine which side of the fuse to enter on you veryify the fuse has power and then pull it out and the side which stays hot is the battery side and the side which loses power is the fused side.
Customer: replied 7 years ago.
They tell me not to wire it to the battery. It needs to be switched.

So to go back a few questions .. do I just pull the fuse and shove them in? Can I do two wires this way or just one?

If you choose to do it this way then yes you stick both wires in beside the fuse. I dont know whom told you to use fuse 2 because this is not a switched fuse. Its hot all the time.


Edited by Chris (aka- Moose) on 12/19/2009 at 6:08 PM EST
Customer: replied 7 years ago.
I have to take my kid to his hockey game. I will get back to you. Fuse 2 is the seat heater fuse by the manufacturer. I thought it is the right fuse. Maybe I need to find another. Any suggestions?

Since your seat heater has its on fuse and on/off switch then it really needs to go to the battery. Anytime you steal power from another circuit you risk the chance of overloading that circuit and blowing that fuse or damageing the fuse panel.

I only provided methods to hook it up to a fuse since that what you asked for, but I feel it would be a better choice going to the battery.

Customer: replied 7 years ago.
The manufacturer expressly says not to wire direct to the battery. They don't say why. I assumed it is because they don't want you draining the battery if the car is off. The owners manual identifies Fuse 2 for the seat heaters. The vehicle hasn't had seat heaters so I assume this circuit is open. I also assume that it was switched. I will test it to be sure as you have told me it is not switched.

I only had this morning to work on it. It this link took much longer than I was expecting. We have company now and I have to leave the house early tomorrow and will be gone all day. I will try to wire it up Monday. Hopefully it will go smoothly. If not is there someway I can get back to you?

I dont have this car currently in my driveway right now so I cant verify myself, but when I login to the ford website and pull up the wire diagram its shows fuse 2 under the dash hot at all times so this is no one bit different than hooking it to the battery.

You can get back to me anytime simply by logging in and replying.

Customer: replied 7 years ago.
I haven't gotten back to you because I ran out of time. Your last response took 2 hours to get back to me. I won't get back to the job until Tuesday. I will then see if it works. I will be sure to test the fuse to see if it's switched.

Don't worry, I am honest and will pay the fee. I appreciate your help. I just want to be sure that it works.
Keep me in touch, I can only reply when I have some free time, during the day when I reply its when I have free time from my day job as a tech. When I reply at night I am sitting on the couch watching TV and am online for about 4-5 hours.
Customer: replied 7 years ago.

I promised you I would finish the seat heater on my wife's car today and then, hopefully, accept your services.

I forgot to tell my wife to leave me her car today. She's on vacation tomorrow and I get out early so I will work on it tomorrow and see if it works.

Don't worry. I will get back to you.

No problem I will be online through out the holiday off/on so reply at anytime needed.
Customer: replied 7 years ago.
I'm back at it. You're right, the fuse 2 is on all the time. I've tried the open fuses but they're hot too. I'm still looking for a switched fuse.

Since each heater has it's own fuse, does it matter if I use a 5 amp circuit as long as I take the power on the hot side, before the juice runs through the fuse? Can the wire gauge handle it?

The wires going into the fuse panel and back out are only meant to handle the load thats on them so if you add any additional wiring or load then you can be overloading the wires and burning them up prior to a fuse, this is why I said go straight to the battery. If you want a on off circuit then you need to wire into the ignition switch and then to a remote relay then to your seat heaters.
Customer: replied 7 years ago.
I cannot wire directly to the battery. The seat heaters will drain the battery if left on - which is a virtual certainty. Do not tell me to wire directly to the battery.

Please explain how I do the last sentence in your reply - "wire into the ignition switch and then to a remote relay then to the seat". How do I:

1) wire into a the ignition switch,
2) wire from the ignition switch into what remote relay
3) how do I tap that remote?

There are unused circuits in the fuse box. I don't know about unused relays.

There is a power distribution box under the hood with easily accessible relays. Is that an option? How do I run wires through the firewall. I don't see any gaps - only fittings which are tight.

You should not be wiring anything into the current fuse panels at all. All these circuits are called for. If you add 20 amps on any of them you can suffer burnt up wires (fire)


To wire in a remote relay you nust first off buy a relay. A relay needs power from the battery and power from the ignition switch in the steering column. Then you need a ground and a wire going out to your products. The ignition turns on and then energizes a relay. The relay closes and allows battery voltage to flow through to your components. The relay will only be on when the key is on.

Customer: replied 7 years ago.
The owners guide lists relays 4,6 & 7 on the back side of the fuse panel as open. Are these an option? If so, can I access them without pulling the fuse box out?

How are the original OEM seat heaters wired up? Can't I just use that circuit?

The factory heated seats use a module to turn the heat on and off.


The empty slots on the back of the interior fuse panel are not even wired up.

Customer: replied 7 years ago.
Okay, so what do I do?
Since the battery is not a option for you. Nor is tapping into a constant power wire from the fuse panel. Then you must build your own relay block and go from the battery and ignition switch.
Customer: replied 7 years ago.
Let me understand.
Here's what I know:
The owner's guide shows the mapping of the fuse box. Fuse 2 is for the seat heaters. There is a 20 amp fuse in the slot but the vehicle did not come with seat heaters. I know the circuit is hot all the time because I tested it.

The seat heaters come with their own 10 amp fuse in the line.

The instructions for the seat heaters say I need to wire into a switched circuit.

The owner's guide shows a diagram of the back side of the interior fuse box and shows 7 relays. It states that relays 4, 6 & 7 are open.

What I want to do is to use the existing seat heater circuit, with the fuse that is there but unused and the relay that I assume is there and also unused.

Here's what I think you are telling me:
The circuit for the seat heaters may be there but there's no relay for me to use.

I can't use the seat heater circuit that is there, even though its live. I have to run a whole new circuit.

To run a whole new circuit I need to buy a relay. I need to run a low voltage wire from the ignition on the steering column to the new relay. I need to run a higher voltage power line from the battery to the relay. Then I need to connect the seat heater power to the relay.

Please confirm, or advise.


The factory seat heater uses no relays at all. It always has power. The module the seat heater uses, uses another circuit to tell if the car is on or off to allow for seat heating or not as well as the climate control system.


Those empty relay holes in the back of the fuse panel have no power or wires to them. You would have to build your own fuse box to use them (pain in the butt)


If you want a switched circuit meaning you only want it to have power when the key is on then you must go with a relay. You can go from a fuse which is switched or to the ignition switch.


Here is how a relay works shown below. If you go a parts store they should be able to help you because off road lights or winches etc... all need relays. A relay is just a switch which can carry alot of voltage and hold up to voltage being turned on and off immediatly. Imagine your breakers in home breaker box as the relays and your wall switch as a switch. A switch can handle all that power at once being turned on or off, it would burn up the contacts. But a breaker can.




Customer: replied 7 years ago.
Thanks for getting back to me.
I have an idea what a relay is. What scares me is getting the power from the ignition switch to the relay. I don't know how to tap into the ignition.

How hard is this?

Not hard at all, remove the lower steering column shroud and splice into this wire.


Customer: replied 7 years ago.

I am not familiar with the notations in these scematics.


16 14 RD/LG


I don't know what the 16 is. I assume 14 RD/LG is 14 gauge, Red / what is LG?



The circuit # XXXXX wire gauge is not important. All you need is the Red wire with a light green stripe
Customer: replied 7 years ago.

Thanks Moose, I will work on it tomorrow and let you know how it goes.

I guess my first stop will be at the auto parts store to pick up a relay and some wire.

They didn't mention this stuff when I studied the literature before buying the seat heater.



Thanks for your help.



Your welcome
Customer: replied 7 years ago.
I picked up the relay, wire and wire connections on Saturday. It's been busy here, with the kids being off of school. I printed up the schematics you sent me and am working on it now. I will get back to you.

Keep in touch.
Customer: replied 7 years ago.
I opened up the steering column and imagine my surprise when I found the red wire with the green strip like you said!. I also had enough wire to work with. I tapped into it but had to run to the auto parts store to get the terminal connectors for the relay. The ones I had were the wrong size. Anyway, I'm trying to test to see if I have power from the ignition wire. I connect the other terminal to ground, turn the key on and I don't get a reading on my multi tester. Am I doing something wrong? I am assuming the ignition wire is hot when the key is on. I haven't tried the higher voltage wire yet.
With the key in the run position the rd/lg wire must be hot. Start the car and leave it running and you should find 12 volts on this wire. If you dont then there is no way for the car to be running
Customer: replied 7 years ago.
Back to the seat heater...i have current coming off the ignition wire to the relay. I don't have the other side of the ignition wire circuit on the relay connected to anything and i get power to the seat heater. In other words its not switched.

I followed the advice of the guy at the auto parts store. There are two circuits printed on the relay. The terminals are labeled 30-/-87 and 85-86. (The "/" is the symbol I am using for switch. The 30 - 87 circuit has a switch in between the two terminals. The 85-87 has a box in between the two terminals but I don't have a box on the keyboard. He says the box stands for a magnet.) He tells me that the 30-/-85 is for the ignition circuit and the 86-87 is for the seat heater power. If that is true, why do I have power to the seat heater all the time. Do I have the circuits backward? I would try to switch them but i don't want to burn anything up. If I run the ignition across the magnet, wouldn't that close the switch?


See if this helps.


Customer: replied 7 years ago.
Moose: That works. It appears to be all wired up properly now. I have the car on and turn the seat heaters on and the on light comes on. I turn the car off and the seat heater lights go off - just like they're suppose to. Now I have another problem that I don't think involves you. They don't get hot.

I only put in the one seat heater. It does not get hot. I plug in the one I haven't installed yet and it doesn't get hot either. The on light on the switches come on in both high and low but 20 minutes later the elements are still cool.

The manufacturer's tech support still hasn't returned my call or my email from the 19th. I need a little bit of time to try to research the instructions and find out if I'm doing everything right. I will accept your help soon and if it allows me, I would like to give you a little something extra.



As for your seat heaters not getting hot I cant help there. You may want to plug one straight up to the battery and see if it gets hot. Dont expect them to get like 200 degrees. There only supposed to get up to like 120 if there like the factory ones. 120 is barely felt by bare hands.

Glad I could help on getting the power to the seats, you can add a bonus if you would still like to do once you hit accept.

Chris (aka- Moose) and 5 other Ford Specialists are ready to help you
Customer: replied 7 years ago.
I forgot there was a pigtail with a module on it that I took off the harness to thread the wire through the column. I woke up last night and realized that it was still in my tool box. I connected it and now the heater works.

Thanks for all you help. I was expecting you to quit on my as you went to a lot of trouble for only $15 but you hung in there. You're a professional. I appreciate your help. I couldn't have done it without you.


Glad you got it done, you will now have a happier wife, and thats priceless and a must.

Happy new year.