Please believe I already know what I'm about to say doesn't make sense...my 2002 XK8 steering wheel tilt stopped working and actuating the control on the side of the steering column causes the driver side seat heat to actuate...moving the control knob in any direction turns the heater on moving the knob again turns it off. I removed the tilt motor, and actuated the control knob...the motor rotates until stopping, then the column retracts. I've watched the rotation direction and manually moved the wheel to the upper and lower limits trying to set the right position, but it still will not work when reinstalled. Again this makes no sense to me...the system was working before this. Any help would be appreciated

 

Wow this is a good one. The tilt switch sends 12 volts through one of 4 resistors into a wire that goes directly to the body processor module BPM. So you have an 8 to 12 volt signal going to BPM from this switch. Somehow its toggling the seat heater. This tells me that something somehow must be screwed up in the BPM.

maybe someone has expertise on climate control cold verify if heaters are controlled through BPM too?

if yes, I'd hope for low voltage confusion issues as culprit. Check battery health; put battery on a charger; do a hard reset (Disconnect and touch battery cables together for 30 seconds ).

if no, we'll I can't imagine how an entirely different circuit can control the heaters, let's see what folks think.

don't despair I once had cruise control kidnapp sport button functionality. I think that was battery voltage issue.

nothing got wet inside right? BPM IS behind passenger air bag.

are you from North America? If not be sure to have radio unlock codes in hand to restore radio access after disconnecting battery.

another post discussion is about seat heater. I'm going to see if the diagram shows the BPM in the loop.
confirmed: seat heater switch goes through BPM.

BTW is it affecting just 1 seats heater?

 

Deeli,

OK we confirmed that both seat heater switch and tilt switch go to the BPM.

Open questions:

1) Battery voltage / health - have you tested or charged it?

2) Could the BPM have gotton wet?

3) Do you live where you need a code to enable the radio? Answered: No Yorktown VA is USA. Its ultra rare to find a USA car that needs the code, only one I ever heard of was a gent who purchased a replacement radio from Europe. (Can't see address info under your name in the mobile phone app, thats why I asked)

4) Feel like trying the hard reset after you know battery / voltage is good?

5) Which seat heater goes on? one or both?

Side bar question: If you turn the tilt switch to off (prevents movement when key is inserted 2nd time) does it all work differently? Not sure how we'll interprit that but just wanted to ask mate. Frankly my switch hasn't worked properly in so long I forget if OFF terminates manual movements as well. (I have bypassed this switch and put 4 switchs next to the valet up down in out motors fed directly from fusebox)

I just typed this to consolidate my previous note to you and include the few updates I found. I'm betting on a low voltage issue, keep us posted.

John

 

John, thank you so much for your response...ask to the questions, the battery is in good condition (have had battery tender on it) this car is not driven regularly, so try to keep charge up...the car is garage kept and hasn't even been driven in the rain...no i don't need code for radio (I've actually done a hard reset, to no avail)...only the drives side seat heat is affected and that happens in the auto and off switch setting.
Thanks

 

May be no help at all but looking at my diagram for a common denominator shows body control pin 87 (connector FC14) connected to steering tilt and pin 86 seat heater involvement. Might it be possible a connection between the two pins has occured?

 

Good question Baxtor, who'd have thought the 2 pins were right next to each other. Itd be easy enough to disconnect battery and unplug /plug connector a couple of times to see if it helps.

I've been meaning to look at mine since the tilt button stopped working years ago.

I wonder how hard it is to remove and open the BPM if simple plug reset is ineffective, anyone know?

John