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Hello thank you for reading this any advice us greatly appreciated. I have a 1992 Lexus Sc300. it has a radio up front and an external amplifier in the trunk. i am trying to put in  A56815 toyota radio. i have already made an adapter harness from the oe lexus radio plug to the new toyota plug. the radio i chose has an internal amp. sound quality is not a huge concern. i bypassed the factory amp in the trunk using a custom harness i made(one end of the harness plugs into the wires coming from the radio the other end of the patch harness plugs into the plug that goes to the speakers. the purpose of this is too not have to run new wires. the radio comes on and works but only for a bit then shuts off. the back of the radio is hot enough to burn you. the oe radio send one ground to the bypassed amp in the trunk. i then split that signal ground into 4 grounds 1 going to each speaker. the factory speakers are 4 ohm. does anyone know whats going on or have any ideas on what i can try to get the radio to continue working. thank you so much

radiodiagram.jpg

Edited by SC300 Guy

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15 hours ago, SC300 Guy said:

Hello thank you for reading this any advice us greatly appreciated. I have a 1992 Lexus Sc300. it has a radio up front and an external amplifier in the trunk. i am trying to put in  A56815 toyota radio. i have already made an adapter harness from the oe lexus radio plug to the new toyota plug. the radio i chose has an internal amp. sound quality is not a huge concern. i bypassed the factory amp in the trunk using a custom harness i made(one end of the harness plugs into the wires coming from the radio the other end of the patch harness plugs into the plug that goes to the speakers. the purpose of this is too not have to run new wires. the radio comes on and works but only for a bit then shuts off. the back of the radio is hot enough to burn you. the oe radio send one ground to the bypassed amp in the trunk. i then split that signal ground into 4 grounds 1 going to each speaker. the factory speakers are 4 ohm. does anyone know whats going on or have any ideas on what i can try to get the radio to continue working. thank you so much

radiodiagram.jpg

you need a separate wire pair per speaker.  you will need to run new wire to the trunk to intercept the separate speaker wiring - four wire pairs for 8 conductors total).  easiest way to do this is get some Speedwire (9 conductors color coded to match Metra standards - you won't use the blue wire)

you are shorting the amplifier outputs in the Toyota radio.  it likely has voltage on both (+) and (-) signal wires (common for most head units).  so by combining the (-) wires is the same as combining the (+) wires - which will cause your issue.


2014 Accord Sport build log:

My YouTube Channel: https://www.youtube.com/channel/UCkYUo2EShW9lgtrfXiDvLNQ/videos

My 1966 MGB Restoration: http://www.mgexp.com/journal/keephopealive

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2016caraudiologos (2).jpg

 

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ok i will make sure each speaker gets its own ground going to the radio. thank you very much, ive been close to tears trying to figure this out

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1 hour ago, SC300 Guy said:

ok i will make sure each speaker gets its own ground going to the radio. thank you very much, ive been close to tears trying to figure this out

You want this: https://www.bestbuy.com/site/metra-20-multiconductor-cable-for-most-vehicles-blue/8267984.p?skuId=8267984&amp;ref=212&amp;loc=1&amp;gclid=Cj0KCQjwgOzdBRDlARIsAJ6_HNns2ewTW4guWgBWuAA5WbbJDvrD7c5F5EbBv9j8O7Rih8pD_eDiQrIaAgcHEALw_wcB&amp;gclsrc=aw.ds

It has 9 conductors. 2 per 4 speakers is 8 and 9 is the remote turn on which you may not need. 


I AM The Future of personal transportation, NOW!!
Pretty sure everyone on this site hates you (@JohnKuthe) more then me and that's very hard to accomplish.

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i could use it the car has its own amp for the factory sub, i dont know how to get it working again. it needs a turn on wire? 

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On 10/8/2018 at 1:55 PM, SC300 Guy said:

i could use it the car has its own amp for the factory sub, i dont know how to get it working again. it needs a turn on wire? 

you will need to turn the amp on, for sure,  using the remote output from the HU (note this wire cannot power the factory amp, it can only send a low current turn-on signal).   you also need to adapt the head unit outputs to the amplifier inputs - this may require changing voltage ranges.  PAC audio, Metra, and USA Spec sell interfaces for this purpose if you search for your year/make/model/trim of your vehicle.   Given that the factory amp appears to use a low voltage arrangement with a common shield, it is possible you can just wire the RCA outputs on the head unit directly into the factory wiring (i.e. FL +, FR +, Front Shield).


2014 Accord Sport build log:

My YouTube Channel: https://www.youtube.com/channel/UCkYUo2EShW9lgtrfXiDvLNQ/videos

My 1966 MGB Restoration: http://www.mgexp.com/journal/keephopealive

Fix Photobucket Image Loading ------> https://addons.mozilla.org/en-US/firefox/addon/photobucket-fix/ <------

2016caraudiologos (2).jpg

 

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the radio doesnt seem to have outputs for an amp. i would need a non amplified signal to send to the subwoofer amplifier, Correct? below is the radio i am using. the radio has an internal amplifier

 

TOYOTA 55838 car stereo wiring diagram harness pinout connector.jpg

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Ah, then you would need a line output converter to take a speaker level (high) signal down to a line level (low) signal.


2014 Accord Sport build log:

My YouTube Channel: https://www.youtube.com/channel/UCkYUo2EShW9lgtrfXiDvLNQ/videos

My 1966 MGB Restoration: http://www.mgexp.com/journal/keephopealive

Fix Photobucket Image Loading ------> https://addons.mozilla.org/en-US/firefox/addon/photobucket-fix/ <------

2016caraudiologos (2).jpg

 

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i will get that, so i need to split some lines such as fr+ and fr-. what should i use for the woofer amp turn on wire?

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some line output converters include a circuit to sense when an audio signal is present and turn the amplifier on.  That would be a good choice.   David Navone Engineering has one, Audio Control does as well.


2014 Accord Sport build log:

My YouTube Channel: https://www.youtube.com/channel/UCkYUo2EShW9lgtrfXiDvLNQ/videos

My 1966 MGB Restoration: http://www.mgexp.com/journal/keephopealive

Fix Photobucket Image Loading ------> https://addons.mozilla.org/en-US/firefox/addon/photobucket-fix/ <------

2016caraudiologos (2).jpg

 

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that is some amazing information. i starting looking at your accord build, good stuff!, lc2i is that what im looking for?

Edited by SC300 Guy

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