SMARK

I am considering the replacement of the Lexus Premium Sound System head unit in my SC300 with a head unit that has a setting to disable the built-in amplifier. Assuming that I want to use the existing speakers and sub woofer, how can I determine in advance that the non-amplified signal from the new head unit will operate with the OEM amplifier in the trunk?

I am going to connect it with the 70-8112 integration harness.

dentpusher

That harness will work and if you want to use the sub you need to splice a rca into the black and white wire on the smaller plug with a violet and blue with white stripe wire in it as well. The black is the pos and white neg.