Car Stereos: create and aux in, car stereo speakers, toyota sequoia

Question
I was wondering if I could tie into the input side of the Toyota Sequoia (2003) audio amplifier to run my iphone through the car stereo speakers.

In general could I connect in parallel or must it be switched in?  

Answer
Hi Robert,

As far as I can tell, the Sequoia's amplifier system uses a single-ended, low level input system (very similar to an after-market amplifier) so you should be able to adapt the headphone output of a mobile device to feed the amplifier's inputs.  The only concern I'd have would be level-matching; ie, whether the output level of the iPhone will be comparable to the head unit's output level.

Personally, I'd probably play it safe and use a 4PDT relay to cut off the head unit's outputs when feeding the iPhone signal to the amp.  According to my wiring information, the signal wires between the head unit and amplifier should be as follows:

Left front:  red
Right front: white
Left rear: black
Right rear: yellow
Common signal ground: brown

It should be sufficient to interrupt the four signal wires and send the iPhone outputs to the amp.  I don't think you'd need to interrupt the ground wire.

Hope this helps!

Brian