The switches are interchangeable, but if the element comes on even briefly the switch is not likely the problem. Theses switches are momentary contact by design and the fact the light comes on (albeit briefly) means the switch is working.
These switches trigger one of two inputs on the heated seat control module (one per seat). If you press the switch to the 'ON' position, it temporarily grounds an input on the module. This tell the module to turn the element on 'HI'. Another press will ground the input again and the module then knows to turn the element on to 'LO'. Repeatedly pressing the switch will toggle between 'HI' and 'LO'. When you press the switch downwards into the 'OFF' position, this grounds a seperate input on the module and the element is turned off.
The symptom you're describing occurs because of the design for a couple of reasons.
1. The element is bad. This is a common problem with these seats.
2. The fuse is bad (see below). There is one for each seat located in the rear fuse block.
3. The module is bad.
There is one module per seat. It is attached to each of the front seats and is probably 4"x4"x1.5" and has two connectors plugged into it. On has 10 cavities and is white, the other has 6 cavities and is gray. The module itself will either be tan (most common) or black. The modules are identical and also interchangeable between the front seats.
The heated seat modules have power applied constantly. In order for them to turn on, the ignition must be 'ON'. Even if the fuse is bad, there is a 12V signal (IGN 'ON') applied to one input of the module when you press the switch. This can cause the light to illuminate briefly, but without the constant 12V supply present (supplied via the fused line), the module will not "latch" on, nor will the element warm.
There have been people who've been able to repair a common wire break in the seat cushion element wiring, but you need to remove part of the leather. I don't always recommend this repair because you need to be proficient at wiring repairs and soldering. There is a service kit available. For your car it comes with three elements that must be replaced as a set. This also includes the ones in the seat back.
Let me search around and see if I can find the write-up for the repair.
StingRay Bike w/cards in the spokes, Weeeeeee!
Last edited by ddalder; 02-21-2009 at 06:42 PM.