Definitive Guide: Power Heated Seats in an XLS

[96firephoenix]

I still need to come back with pictures and to double-check the wire colors on everything, so it's not definitive yet.

I've done what was thought to be impossible: Power, heated seats with full function into a base model XLS without cutting the harness on the truck. For what it's worth, it used to be a memory seat. The memory does not function because there is not the other 40 bajillion modules that the memory module communicates with, let alone the wiring harness to install them... you'd need an entire interior swap down to the studs, and at that point, its easier to just buy a different car.

I know a few guys out there have had issues with the power driver's seats not working after installing them, or with no heated seat function. I know a couple guys have write-ups that involve cutting apart the wiring harnesses for the seat belt anchor switch or for the pretensioner.

It was not easy, and I would not recommend this for the faint of heart or short on time. My driver's seat contains parts of 3 different vehicles, but everything bolts in, plugs in, and works.

Tools:

• 13 and 15 mm sockets
• Phillips screwdriver
• Wire splicing tools
  
• wiring connector de-pinning tools.
• Pliers
• Hammer (Maybe)
  
• T50 torx driver (Maybe)
• Step drill bit (Maybe)
• Needle file (Maybe)

Parts list:

• Auxiliary circuits - however you want to run these is your choice, but you'll need a constant hot and a hot in run each with a 20A fuse. There's no end of instructions or methods to add circuits to your vehicle.
  
• Power heated driver's seat from 2002 Explorer/Mountaineer or some 2003 explorers/mounties
  
  • This is because they have the heated seat module on the seat itself, instead of being routed through the EATC. To determine this, flip the seat over, and look at the leading edge - there will be 2 electronics boxes, one for the heater, one for the memory.
• Power passenger seat
  
  • You need the wiring harness that goes from the switch to the motor pack.
    
  • Pro-tip: find a damaged seat at the junkyard, they won't care if you rip it apart.
  • Doesn't matter what year for just the harness
• (Optional) Power heated passenger seat from 2002/some 2003 explorer/mounty - depending on if you want the front seats to match.
  
  • same deal with the heated seat module, except no memory module.

Procedure:

1. Examine your manual seat for the seat position sensor.
   
   1. On the outside frame rail, there will be a 3-5 inch magnet and a magnetic switch to determine the distance from the steering wheel 2-stage airbag.
      
   2. If the Power seat does not have this, you will also need the seat rail from a power seat with the sensor. This is only if you are dead set on your airbag working properly. Otherwise, just plug it in under the seat and your airbag will be limited to a single-stage deployment in a collision - this is something that I think you would be morally and perhaps legally obligated to disclose upon sale of your vehicle. (Instructions on this will be separate)
      
   3. If your car doesn't have this to begin with, it doesn't matter one way or the other if the donor seat has it.
2. Modify the spare passenger seat harness.
   1. There will be 8 wires in the harness - Red and black for Pos/Neg power, and then 3 pairs of Red and Yellow wires with colored traces (Mine were: red/white, yellow/white; red/blue, yellow/blue; red/green, yellow/green).
      
   2. De-pin each pair and flip the terminals in the connector that they go into, so that the red/white ends up where the yellow/white began and vice versa. Alternatively you could cut and splice each pair to the other color, but it's a cleaner install if you can re-pin the connector.
   3. De-pin the red and black wire from the end where they connect to the floor (you can just cut this if you want, but make sure that there's a long lead from the switch connector.
3. Completely strip the wiring from underneath the seat, including removing the memory and heater control units.
   
4. Discard the memory unit.
   
5. Separate the wiring harness into parts that went to the memory unit and parts that went to the heater unit. It's best to cut the sheathing and strip the harness so that you can maximize the length of wire that is available.
   
6. Cut out the parts of the harness that don't go to the heater unit.
7. From the floor connector to the heater unit, you'll need the purple/orange trace wire, the black/yellow trace wire, and the red/white trace
   
8. Remove the connector anchor from the power seat rack. This is a plastic piece that spans the seat rails that does nothing but hold the connector ends. (4x phillips screws)
   
9. Remove the seat belt anchor/pretensioner from the power seat. (2x 13mm bolts)
10. Remove the manual seat. (4x 15mm bolts)
11. Remove the seat position sensor from the manual seat (1x phillips screw)
    
12. Remove the seat belt anchor/pretensioner from the manual seat. (2x 13mm)
13. Remove the connector anchor from the manual seat rack. This is a metal piece that screws to a seat rail that does nothing but hold the connector ends. (2x phillips screws)
14. Install the seat belt anchor/pretensioner, the seat position sensor (See Alternate seat rail instructions below, if necessary), and the connector anchor to the power seat rack.
15. Install the power seat, connect the wiring, boogy on.

Wiring (I'm going to go back and double check the colors to be certain):

1. Seat switch Red and heater Red/White to Hot at all times
2. Seat switch Black and heater Black/Yellow to Ground
3. Heater Purple/Orange to Hot in run.

Alternate seat rail instructions:

1. Remove the T50 screw that holds the seat rail to the threaded rod.
2. Pull the seat rail all the way rearward.
3. Use pliers or a prying tool to lift the tabs in the bearing race.
4. Push the seat rail all the way forward and off the seat rack. There will be 4 ball bearings and 2 plastic guide rods. Do not lose these.
5. Do steps 1-4 on the seat rail that has the magnet for the position sensor.
6. On mine, I had to use a step drill bit and a needle file to increase the hole where it attaches to the threaded rod from 1cm to 0.050 over 5/8". YMMV
7. Put bearings and plastic rods in the bearing track at the front of the seat rack.
8. Install the seat rail with the magnet and pull it all the way rearward. You may need to work it back and forth a couple times to get the bearings to not come all the way out the back. I used the plastic rods from the seat that is going in the scrap heap to push the bearing stack down while pulling back on the seat rail.
9. Bend the tabs back down to lock the bearings in the track.
10. Add a dab of grease and work it back and forth a few times.
11. Attach the rail to the threaded rod, and tighten the T50 screw.