Good morning all -

I'm hoping to run this by you good folks. In my 1997 XK8, the passenger side seat heater comes on and goes off by itself, whether there is anyone in the seat or not. It seems to come on when there is forward motion, and turn on and off while driving, and turn off when braking (when the car is pitching forward). When it is on, I cannot turn it off, the button on the dash won't work. When it is off, I can sometimes turn it on and off using the button but not always. When it turns on and off I can hear a click, like an electrical relay, somewhere under the dash.

Do you think its just a relay or two that needs to be replaced, or the entire seat module? Is there a way to disengage the seat heater but leave other seat functions enabled?

Thanks for your help -

Pete

 

There are no relays involved in the seat heating circuits! The heaters are powered directly from the Driver's and Passenger's Seat Control Modules, but the switches are wired to the Body Processor Module which passes the demanded On/Off states to the Seat Control Modules through the Standard Corporate Protocol (SCP) network.

The intermittent nature of the fault suggests that a loose or dirty connector could well be the cause. The seat module is the most exposed and moved about as the seat moves, so I would start there. The heater wire in question is the Orange/Pink one on Pin 3 of the 16 way Black plug. The SCP connections to the Seat Control Module are the Blue and Slate wires on Pins 9 and 10 of the Black 10 way plug

 

I've filed your Pin and cable colour details away for future reference as anything to do with Seat Modules could fail at any time!

What is the cause of the 'click' from somewhere behind or below the Glove Box when the heaters are switched on?

Graham

 

First, for Graham, please note that those wire colours and Pin Numbers are only applicable up to about MY99 after which almost the whole wiring set up changed!

With regard to the clicking, I would (respectfully!) ask Pete to confirm that his clicking is from under the dash as opposed to under the passenger seat. It's just that when the passenger seat module does click, as it should switching the heaters on and off, it does sound very much as though it's from under the dash when sat in the driver's seat!

Although I said there are no relays, what I should have explained is that there are no relays in the sense of the plug-in, replaceable/checkable types that we're all used to. However, built into various modules there are non accessible relays that click when they switch over.

 

If it wasn't after midnight and pouring with rain, I'd go out and lie down in the passenger footwell to check my click.

The excitement will just have to wait until morning.

Graham

 

Hello guys - thanks for all of the replies - I will try tonight to find out for sure whether or not the clicking noise is coming from the dash or from the passenger seat and will let you know.

 

The 'click' on my 2005 definitely comes from behind the Glove Compartment.

Graham

 

sounds like deathwatch beetle to me

 

I never want to get that again.

Graham

 

just been out to my car the heated seat
click comes from behind the dash in the glove box..
did you creasote yer wooden leg to get rid?

 

Funny old world, especially as Graham and I have the same MY cars!! I've re checked mine and the click is definitely from under the passenger seat for that heater and under the driver's seat for its heater. Do both your heaters click from behind the glove box? - which of course is where the Body Processor Module is located!

The other click that the seat modules throw out is for the foldback mirrors. When they are either folded or unfolded, there is a five second delay before they can be operated again - the click as the system 're connects' the joystick comes from the Driver's Seat Module after folding and from the Passenger Seat Module after unfolding because of the way they're wired up - or am I in another minority!!!!

 

It certainly is a funny old World.

As I was waiting for my wife in the Hospital car park last night, I thought I'd check the seat heater 'click'. From the driving seat, it still sounded as if it was coming from behind the Glove Box and not the Seat Module. To be absolutely certain, I went round to the passenger side, knelt down and stuck my head in the footwell.

Next thing I know, the driver's door is opened and someone reaches in whilst someone else kneels on the passenger seat above me. Thought it was a mugging but it was two nurses going off duty and concerned I'd been suddenly taken ill!

Did I admit what I was doing? Not b****y likely. They'd have had me in the Psych Ward before the engine cooled.

I'll be postponing any further investigation of 'click' sources until I'm safely home at the weekend.

Graham

 

Good evening gents -

Apologies for the slow reply. Since I couldn't diagnose the location of the click myself - it would not come on while the car was standing still, and wouldn't come on when I pressed the button on the dash - I had to wait until I had a passenger, which was today. Yes, the click is definitely coming from behind (or under) the glove box.

Thanks -

PKB

 

Well, I can't explain that! There is no power connection between the seat heaters and the BPM or anything else behind the dash that I can identify, that would support a 'click' from there! I can only add that the click in my own car appears to come from behind the glove box until my forehead is pressed firmly in the footwell carpet and my ear below the level of the seat!!

Regardless of all that, I still would advise the connector checks given in my first post as the first, no-cost element to a fix!!

 

Astromorg, do you know if your seat heat module and wire/pin color/number are the same for a 2007 XKR? My seat heat is not working on drivers and only the back is working on passenger so I suspect loose wire. Any help would be greatly appreciated.

 

Sorry, I don't have any technical details for the later (X150) models! But it's always worth checking out under the seat for loose connectors or frayed wires.