Troubleshooting heated seats
 

Hello all,

I have replaced the heated seat bottom in my 2003 discovery. I have confirmed the fuse is good #15. Light is on on the switch but no heat. Same with the passenger side. Does anyone know what relay controls the seats? Or what else I should look at?

Thanks

I might be wrong, but doesn't the Heated Seat Module AWR500030 have the relay and the logic circuit in it? And if the Aux circuits Relay is involved that would be R7 under the hood fuse box. I don't remember the part #.

They are located under the seats and look like this > Heated Seat Module (Genuine Part # AWR500030 ) - Land Rover switches/control unit/actuators from Atlantic British

From RAVE:

Seat Heating Description

The heated seat elements for each seat are supplied power from a seat heat
module located on the underside of the seat frame. The seat heat module
provides consistent temperature control of the seat heater elements. A
negative temperature coefficient variable resistor is located in the seat cushion
heater element. The resistor changes its resistance as the seat cushion
temperature increases or decreases. The resistance is monitored by
electronics within the seat heat module, which raises or lowers the power
supplied to the elements and controls the element temperature between 26 and
36¼ñêôC (79 and 97¼ñêôF).

The heated seat elements are operated by a latching seat heater switch for
each seat located in the centre console between the two rear window switches.
The heated seats only operate when the ignition switch is in position II.
Circuit Supply

A feed from the battery positive terminal is connected on an R wire to the
engine compartment fusebox where it passes through fusible links 1, 5, 7 and
8. Fusible links 1 and 5 and 1 and 7 are connected in series.
A feed from fusible links 1 and 7 is connected to the contacts of the auxiliary
circuits relay.
A feed from fusible links 1 and 5 is connected on an NG wire to connector
C0255-5/C0751-1 interface. From connector C0751-1, the feed continues on
an NP wire to the coil and contacts of the LH power seat relay. The earth path
from the relay coil is connected on an OP wire to the BCU pin C0663-3, via
header C0724.

A second feed from fusible links 1 and 5 is connected on an NP wire to the coil
and contacts of the RH power seat relay. The earth path from the relay coil is
connected on an OP wire to the BCU pin C0663-3, via header C0724.
The BCU completes the earth path when ignition I or II or driver’s door open is
sensed.
A feed from fusible link 8 is connected on an NW wire to the passenger
compartment fusebox and from the fusebox to the ignition switch on an N wire.

Ignition Switch Supply
With the ignition switch in position I or II, the feed from fusible link 8 passes
through the ignition switch to the passenger compartment fusebox on an LGW
wire.
The feed continues through fuse 26 in the passenger compartment fusebox
and is connected from the fusebox on an LG wire to the coil of the auxiliary
circuits relay in the engine compartment fusebox. This feed energises the relay
coil, closing the relay contacts. The relay coil is earthed on a B wire, via header
C0286 LHD/C0288 RHD, to earth header C0018.

Seat Heating Operation
With the auxiliary circuits relay energised, the feed from fusible links 1 and 7
passes through the relay contacts and is connected to the passenger
compartment fusebox on a WG wire where it passes through fuse 15.
From the passenger compartment fusebox, the feed is connected to header
C0761 on an LGW wire. From the header C0761, the feed separates into two

LGW wires which are connected to the LH and RH seat heater switches.
From the LH seat heater switch the feed is connected on a US wire to
connector C0225-1/C0751-1 interface. From connector C0751-1 the feed
continues on an OW wire to the LH seat heat module.
From the RH seat heater switch the feed is connected on a UK wire to
connector C0253-1/C0751-1 interface. From connector C0751-1 the feed
continues on an OW wire to the RH seat heat module.
Power is supplied to the electronics within the LH or RH seat heat module by
the feed from the LH or RH seat heater switch. This allows the feed to pass
through the module and is connected to the LH or RH seat cushion heater on a
K wire. The LH or RH seat squab heater is connected in series from the LH or
RH seat cushion heater on a KW wire. The LH and RH seat squab heaters are
connected to earth header C0708 on B wires via splice joint 1.

The earth from the LH or RH seat heat module is connected on an LG wire to a
temperature variable resistor contained within each of the LH and RH seat
cushion heaters. As the temperature of the seat cushion heater increases, the
resistance of the resistor changes. This is sensed by the seat heat module
which varies the power supplied to the LH and RH seat cushion heaters,
raising or lowering their temperature accordingly.

The resistors are connected to the LH and RH seat heat module on B wires
and from the LH and RH seat heat modules to earth header C0708 on B wires
via splice joint 1.

Thanks guys, today I figured out my heated seat does work slightly but the driver's is not all that warm. It has hot spots on the sides and then not much heat in the middle of the bucket. Probably b/c I got it from a 1999, so it is 16 years old. Next I will attempt to pull the seat squab leather and swap out the new element I have form BP Utah. There are metal rails with rings in the foam that look tricky to disconnect but i will figure it out and report back.

The rings are not that difficult to take out. Harder to put back in. They use hog rings and I used just a pair of dykes to cut them off. Some quality zip ties make the job easier to replace. Hardest part is re-stretching the seat and putting the clips back on that hold it to the chair frame.

Quick splice makes for warm tush
 

My driver's side seat heater was not working, so I unfastened the upholstery and inspected the heat pad/foam underneath. There was a odd "divot" in the foam on the left hand bolster, where the insulated wire had wore through (from sliding in and out of the seat) and literally burned into the foam, causing the divot.

I stripped back the insulation, slipped a piece of shrink wrap over the wire, tied a knot in the exposed wire and shrink wrapped the knot and exposed wire on each side of the knot. Tucked the shrink wrapped section into the little "divot" and buttoned everything back up...

Voila! Warm tushy again.:p

I have the same problem. One spot was getting too hot and the seat top melted made a hole. Now the heater does not work. I am assuming this can be repaired. Probably the heating wire burnt and cut off. Not sure until I get there. Thanks

Thanks for this post! I did the same repair above and the heated seats worked but lasted only several months. I guess the "getting in and out of the driver seat" wears out the wire and the wire broke again. Besides replacing the heated seat element, is there a better repair I can do?

Thank you very much!