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I was able to find a treasure trove of information on the IS250 amp and it’s wiring on this forum, but sadly, thats not the case with the IS250c.
The IS250c that I recently purchased (new club member!) has the navigation package, not the Mark Levin version. The amp kinda looks like the amp in the IS200t, but the wiring colors are different.
My plan B is to t-tap into each of the wires coming out the amp and try to figure out which corresponds to the front woofers and tweeters by changing the balance/fade and treble/bass on the head unit and seeing how the voltage in each wire changes. The goal is to route the speaker level outs to my aftermarket amp.
My plan A is to find a wiring diagram or see if anyone on this forum has tried to reverse engineer this amp before.
In any case, I’ll post my progress (or lack there of) here so others can learn from my mistakes. If there is a source that I should check out before mindlessly ripping out wires, that would be super helpful.
Thank for the screen shots!
I went ahead and took out the door panels so I could test conductivity from the harness.
For any future 2014 IS250c owners that are looking to install a third party amp, check out the pictures below. I don’t know which is positive vs negative, I’ll try to figure that out from the service manual pictures above.
Label Guide
RT TW - Right mid speaker and tweeter - Gray+Black
RT BS - Right bottom speaker - Pink+Brown
LT TW - Left mid speaker and tweeter - Blue+Green
LT BS - Left bottom speaker - Red+White