New guy here !!!!

'03 F-150 Super Crew, two wheel.

The driver's side heated seat went to warp factor three a few days ago. Since then, just cold buns. I traded the passenger's side switch for the driver's side. No change, only the passenger's side works.

The #36059 Haynes manual does not show a wiring diagram for the seats.

Anyone have a schematic for the heated seat circuit ?

I suspect the element has fizzed-out but without a diagram, trouble-shooting is on hold. (The driver's side has, if memory serves, four connectors yet the passenger's side only three...the lighted switch is identical for either side).

BTW, the seats are full power and leather, if that matters.

ANY help will be appreciated !!!

Ed in 'ol Virginny

 

There is a 30A maxi fuse (#118) in the Battery Junction box under the hood. If this fuse was blown, both seats would dead, for all functions.

There is a 10A fuse (#23) in the fuse panel under the dash above the emergency brake pedal. This fuse is for Trailer Tow Battery Charge Relay, Turn/Hazard Flasher, 4x4 Solenoids, 4x4 Relays, Overhead Console, 4 Wheel Anti-Lock Brake System (4WABS) Module, EC Mirror, and Heated Seats. If this fuse is blown both seat heaters would be out as well as these other items.

Each seat contains a Heated Seat Module which controls the cushion heaters. Power into each of these units is on four wires, Red/Black (from the 30A fuse), White/Light Blue (from the 10A fuse), Dark Green/Violet (from the seat heater switch via the 10A fuse), and Orange (from the indicator light in the switch). There is a Black wire that grounds the HSM.
Out of the HSM to the heater element is a Yellow/Light Blue. This feeds the seat cushion heater elements (cushion and back) which are in series with the return wire being Violet/Light Blue. Between the two elements is a Gray/Light Blue wire. Each seat also contains a pressure sensor potentiometer which is contained in the cushion heating element. Out of the HSM to the sensor is a Black/Light Blue wire. Return to the HSM for the sensor is a Brown/Light Blue wire.

Hope this helps you out.

 

BTW Ed, welcome to FTE.

 

Whew !!!!

What a complete answer !!!

You can be certain that the 'ol Fluke and I will be busy utilizing the aforementioned !!!

Ed in 'ol Virginny

 

Does this mean that the heater only works if someone is sitting in the seat?

Neither of my seats have heat- both heater lights do come on though. I tested the passenger seat this morning but no one was sitting in it.

All fuses are good.

No wires were seen to be split- removed upholstery as far as I could without cutting hog rings.

 

Ohm out the continuity of the seat heater pads. You should read some resistance, If it's open then it's most likely a break in the heated seat coil (usually near where the seat bun upholstery raises up near the back. It's a fairly easy fix, but you'll need to remove the seat and you'll need some hog ring pliers to put the seat cover back on.