After Market Radio Harness AMP bypass

Elvis · 01-29-2011, 05:57 AM

I am a proud owner of a 92 MKIII. While the car does need a little love, I thought I would start with a aftermarket stereo. I have installed more car stereos then your average person. I have always hated the idea of cutting the factory wiring. I am a big fan of the aftermarket harness. There are connections on the radio that I have never seen before. The factory radio has 2 antenna leads. One is the standard one that fits nearly all non-GM cars. And the other is a much smaller one. But the issue at hand is the wiring harness i got from CarToys is not fitting the factory one. Is it possible that the under seat amp has the correct leads for the aftermarket harness? Has anyone been able to bypass the amp and use this aftermarket harness?

cre · 01-29-2011, 08:06 AM

About time you got here.... I pass you everyday on the street and was wondering how long it would take for you to find us.

The premium system is a bit annoying to work around. If you're dead set on not cutting up the harness you'll do well to use the link below for the stereo diagram. My recommendation would be to run new wire and not even touch the factory wiring. The stereo does have two antennas, one's built into the rear window (looks like part of the defroster); This is the one with the smaller plug. The regular size plug goes to the retractable mast antenna. Some people use an adapter on the smaller one and run both into a Y for what they clain is superior reception... some have had ghosting problems from this. If you drive only in the city and don't mind CD's or MP3's when away from the city then the window antenna is nice if you're looking to clean up the exterior and shave certain items. I generally stick with just using the mast antenna on my installs though.

Here's the wiring diagram:
http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=132

Elvis · 02-12-2011, 05:46 AM

Not trying to Shrug off your advice I was just being lazy. But I took what you showed me and added to it. I started looking at the wiring. The "factory" Wiring was there but when they add the under seat amp they also add an additional wiring bundle. This has a Send and return. All I needed to do us unplug the cable from the "factory" harness and install the after market one. I installed a pioneer deck with XM and bluetooth. The Amp is still under the seat but totally dorment now. But the new head unit sounds far better then what the "upgraded" radio did.

Elvis · 02-12-2011, 05:49 AM

I also installed a power mast bypass. That way if I am cranking the XM or IPOD I don't need to raise the antenna. But I never did thank you for your help. Thanks.

01-29-2011, 05:57 AM	#1
Elvis Stock Join Date: Jan 2011 Location: Denver Posts: 3	After Market Radio Harness AMP bypass I am a proud owner of a 92 MKIII. While the car does need a little love, I thought I would start with a aftermarket stereo. I have installed more car stereos then your average person. I have always hated the idea of cutting the factory wiring. I am a big fan of the aftermarket harness. There are connections on the radio that I have never seen before. The factory radio has 2 antenna leads. One is the standard one that fits nearly all non-GM cars. And the other is a much smaller one. But the issue at hand is the wiring harness i got from CarToys is not fitting the factory one. Is it possible that the under seat amp has the correct leads for the aftermarket harness? Has anyone been able to bypass the amp and use this aftermarket harness?

01-29-2011, 08:06 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	About time you got here.... I pass you everyday on the street and was wondering how long it would take for you to find us. The premium system is a bit annoying to work around. If you're dead set on not cutting up the harness you'll do well to use the link below for the stereo diagram. My recommendation would be to run new wire and not even touch the factory wiring. The stereo does have two antennas, one's built into the rear window (looks like part of the defroster); This is the one with the smaller plug. The regular size plug goes to the retractable mast antenna. Some people use an adapter on the smaller one and run both into a Y for what they clain is superior reception... some have had ghosting problems from this. If you drive only in the city and don't mind CD's or MP3's when away from the city then the window antenna is nice if you're looking to clean up the exterior and shave certain items. I generally stick with just using the mast antenna on my installs though. Here's the wiring diagram: http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=132 __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

02-12-2011, 05:46 AM	#3
Elvis Stock Join Date: Jan 2011 Location: Denver Posts: 3	Easier then I thought Not trying to Shrug off your advice I was just being lazy. But I took what you showed me and added to it. I started looking at the wiring. The "factory" Wiring was there but when they add the under seat amp they also add an additional wiring bundle. This has a Send and return. All I needed to do us unplug the cable from the "factory" harness and install the after market one. I installed a pioneer deck with XM and bluetooth. The Amp is still under the seat but totally dorment now. But the new head unit sounds far better then what the "upgraded" radio did.

02-12-2011, 05:49 AM	#4
Elvis Stock Join Date: Jan 2011 Location: Denver Posts: 3	Thanks I also installed a power mast bypass. That way if I am cranking the XM or IPOD I don't need to raise the antenna. But I never did thank you for your help. Thanks.

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