Does the factory fitted start button unit have a built in transponder of some kind? reason I ask is because mine is in quite a bad state and i've purchased hybrid blue power version of the switch, i've checked the connectors and it's exactly the same. The same amount of pins and the connector fits. But my concern is if there is anything in particular inside the unit that will prevent the start. If so then maybe I can dismantle it to take just the push section out.

 

I'm not positive but I don't see it being any different than buying the TRD red push start button. It should work.
https://www.clublexus.com/forums/clu...-is-gs-ls.html
https://www.clublexus.com/forums/is-...ton-start.html

 

I replaced the start button in my 2007 IS350 with one off of a 2010 Lexus ES350 from TLS Auto Recycling because sometimes the car would fail to start on the first button push (as described in TSB L-SB-0161-08 [see attachment]). It worked perfectly and fixed the issue, even though it was a different part number and TLS advised against it. No need to take the switch apart, just plug 'n play!