My son wants to put an after market radio in my 99 SR5. THe factory system is a radio/ casette deck combo and below is a cd player. Coming out of the back of the radio is two plugs. One goes to the cd player. The other is a 15 pin plug. I found a 15 pin female plug online, however i need to know which pin on the factory wiring harness does what.

Sorry photo of radio is upside down.

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Hi, on mobile right now but this website has a lot of good information. This is what I used for my '99 stereo when going to aftermarket. Hope it helps! Link ->http://www.the12volt.com/installbay/...ailm/2028.html

Not sure if this will help, but the aftermarket harness connects to the factory harness after the amp located behind the radio. It has connectors on both sides. I did this over a year ago, so it's kind of fuzzy in my mind.

THanks for that link. Not all of the colors match up to what i have, will look at it tomorrow in the daylight. Should be enough to let us figure the others out.

http://tacoma.site40.net/4Runner_96-...mci/052rap.pdf

Above is from 2002, but I believe '99 is the same. Plugs are designated R1 and R2 and you can find the pin-out diagrams with the terminal numbers at page 241 here:

http://tacoma.site40.net/4Runner_96-...o/connecto.pdf

This is not the plug in your picture, which goes into the head unit. These are the plugs that go into the power amp. You will want to pull and discard the power amp and head unit to amp harness and connect to the plugs that go to the power amp (R1 and R2). The easy way is to purchase an after market pigtail harness for Toyota and marry that to the pigtail that comes with your new head unit. In that case you won't even worry about Toyota colors, you will be working with industry standard aftermarket colors.

You can find these at Best Buy (in some cases), Metra Online | Welcome to Metra Auto Parts Online Warehouse or here: Toyota and scion Into Car Wire Harness - for installing a new car stereo into the car 70-1761 METRA Thus is where I get my stuff for installs. here is the whole menu of stuff you might need:

1999 Toyota 4 runner Stereo Installation Kits, harness, wires, parts, bluetooth, iphone, tools, wire diagrams

This way you avoid cutting the factory harness. I strongly recommend you got this route. Tell the kid to learn to solder and use heat shrink tubing. Crimp-on connectors suck. https://www.youtube.com/watch?v=MhjnaxoUxOQ This guy has got it right which is unusual for a Red Sox fan.

Thanks for the information. Why do i remove the factory amp if I am not installing an aftermarket one, do I not need it?

Your new head unit will provide plenty of power for your speakers. Furthermore, the adaptor plug will not mate with the amp output harness. You need to plug your hand-built harness into the vehicle's plug to the amp.

If your power antenna still operates, you may consider mounting a dash switch to eliminate the constant up and down whenever you start or stop your vehicle. This switch is wired between the blue wires of the two harnesses.

And, if you have the window antenna in the right rear window, you have the dual antenna and you will need a couple other bits. There are two antenna leads to the factory head unit with this setup. One is the common 1/4" Delco or Motorola plug, and one is a micro antenna plug. A y-combiner will be needed (Metra 40-UV43) and a micro/Delco adaptor also (Metra 40-gm12).

Bestbuy usually has this stuff in stock, or you can buy online via the numbers provided.

What @Riceye said. Even if you could wire it up easily, it's a 15+ year old piece of crap and your new HU will sound much better with its built-in amp. You might add a new amp if you ever upgrade the speakers.