So my heated seats don't work, haven't worked since I bought it. Where do I start? What all do I need to check? I'm a budget oriented DIY'er so any help is greatly appreciated!!!

 

1st would be at the fuses. Then I would go to a seat and at the connector check for voltage. You'd have to get a copy of the wiring diagram to see what is in the connector. I would also pull the connector and check the heater resistance and compare to the spec . If it is open then you know the heating circuit has a break in it. But back to the connector . If you don't get the values and the fuses are OK then you need to verify if the infotainment screen is putting a signal out to the relays. If you get in there your are over my head.

 

Since both seats are not working, the might be and indication that it is the fuse as well. Don't just look at the fuse and assume it "looks good" ...change it regardless.
Does the heated steering wheel work?

 

No heated steering wheel. I'll check all fuses again just to be sure. I have the shop manual so I'll check that out too, guess I was hoping for a quick fix or someone who had the same issue with an answer. Don't drive her much in the winter so not a huge deal, but would love to fix it. Thanks for the advice!

 

Sounds like fuses. My drivers heated seat doesn't work, but my steering wheel and pasenger seat does work, and that's typically how it works when one is simply worn out.

 

The only fuse is the 175A megafuse, and if that was blown there are quite a few things that would not work.

 

About two years ago I had the same problem with the passenger side seat in my 12 xk vert. It took the dealer and Jaguar UK engineering about 2 weeks to figure out what caused the problem. The problem lay in the touch switch on the video screen. they replaced the entire screen/switch module under warranty. that solved the problem.

Given that your xk is an 07, I hope that is not the issue that you face.

 

I have the same problem - my driver's seat does not heat, but the passenger seat seems to (as does the steering wheel - though barely detectable - which I can live with).

I am going to start troubleshooting - but I can't get at the connectors under the seat with the seat in place (2009 XK convertible). So my plan is to remove the seat to give easy access to the first troubleshooting steps (is there power, what's the resistance in the coils).

Two questions for you experts:
1) any "gotcha's" to watch out for in removing and reinstalling driver's seat?
2) does anyone know where to find the healthy resistance value for the seat heater coils?

Thanks everyone!

 

Hi,

Just reading this thread. The passenger seat is heating up very hot for me, but the driver's seat only heats the back, not the actual seat.
Is that likely a fuse (are there separate ones for the seat and the back) or a connector. If a connector, how do I access the cables under the seat?

Thanks for any pointers/advice.

Volker

 

not sure what model year you have or if you have an X150 but if you re-read, you'll see there is only the megafuse that powers the seat and the seat cushion and squab are one piece and wired in series. From the service manual:Operation of the heated seats is controlled by the ATC (automatic temperature control) module. When the ATC (automatic temperature control) module receives a heating request from the TSD, it broadcasts a message to the CJB (central junction box) over the medium speed CAN (controller area network) bus. The CJB (central junction box) then provides a hardwired 12 V supply to the 3 heater elements contained within each seat. The 3 heater elements, 2 in the seat cushion and 1 in the seat squab, are wired in series.

The ATC (automatic temperature control) module monitors seat temperature using a temperature sensor located in each seat cushion. The CJB (central junction box) provides the temperature sensors with a 5 V supply. The level of the returned voltage back to the CJB (central junction box) is proportional to the seat temperature. The value of the return signal is broadcast to the ATC (automatic temperature control) module over the medium speed CAN (controller area network) bus which it then converts into a temperature value to allow it to control seat temperature to the required level.
End

So my best guess and it is just a guess, is that your temp sensor is somehow malfunctioning and not sending the correct data back to the ATC. Since the seat cushion and seat back are wired in series, the back should not function if the seat is not heating. TO test the thermal sensor, you should have 5 volts coming out of connector CA130/10 (white and green wire) and 5 volts on the return CA130/2 (White and Black wire). See below for location of the connector.

 

thanks. Yea it’s a 2009 XK / x150.
this all makes sense. Kind of. So sensor or wiring. Might need the seat removed. Cheers.

 

Yes if you have no return voltage I would think thermal sensor which is embedded in the heat pad seat but could also be simply unplugged @ the cushion. Let us know how you get on.

 

Thank you.

 

need to weigh in…
“Wired in series” and only the back works and not the seat.

As they are in series, a connection through the inoperable pad must be made or else the other pad would be inoperable.
Hmmm.

 

@guy agreed, that's why I'm guessing there is no break in the wire but the thermal sensor is not operating correctly and therefor not controlling the temp. Makes no sense to me either.