Heated seat switch misbehaving

[Disca]

Evening all

Thought I had an easy fix on my hands this evening as my drivers side heated seat switch stopped lighting up on the higher level but seemed to work for the lower one.

Turns out on closer inspection in the dark the upper level activates for a split second as you push the switch in before it turns off again and the lower level of heat deactivates after a few seconds...

I tested this with the switch from the passenger side to double check and whilst that switch works perfectly in the passenger side it also behaves weirdly on the drivers side.

Any ideas?

 

[Jjim]

Could be a short circuit on the heating pads or loose connection under the seat.

 

[Ianmc]

Underseat connection has to be next area to investigate, they can get "snagged".

 

[Disca]

Hmm hopefully it’s the underseat stuff as the pad is a new OEM one fitted last year at considerable expense for what it is!

Is checking for snagging a seat out job?

 

[Ianmc]

Likely best to lift the seat, only four fixings.

 

[Clockwatcher]

@Disca,

If I read your problem correctly, it's the drivers side that has the fault. You have already shown the switch is okay (although it would be worth checking the drivers's side switch in the passenger seat circuit and check it works correctly. This will identify if you have 2 faults present, rare, but it happens).

Once you have rechecked your switches, clean and re-secure all the earth points for the heating circuit.

If you have a multimeter available compare the resistance readings for the"good" seat with the "bad" seat. Remember to disconnect the battery before you do this. If the 2 seats give the same readings it will be the wiring loom between the seat and the switch. Assuming the car is a face lift 2.8, the wiring diagrams are below.

You might be able to do this without removing the seat if you set the seat to its maximum height.

DANGER: Make sure you do not "accidentally" test the seat belt pre-tensioner circuit!!!

 

[Disca]

@Clockwatcher cheers for the detailed reply.
Testing electricals is way beyond my comfort zone though so I think I might send this one into Birds to be sorted.