HOW-TO: Combining Front & Rear Factory Antennas into One

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Aftermarket stereos accept only one standard plug, and the output quality isn’t great. What if you have two antenna plugs? The solution? Turn two antennas into one big one!

The stock stereo in ’96 – ’02 Toyota 4Runners utilize a diversity antenna setup that incorporates both the standard front fender antenna and a rear antenna embedded into the right rear glass of the cargo area. Each antenna then plugs into the factory stereo – one standard size plug for the fender mounted antenna and one smaller plug for the rear embedded glass antenna. However, aftermarket stereos only accept the standard size front fender antenna plug. When I installed my new Pioneer AVH-P4100DVD receiver,  it would only accept the front standard antenna plug. As such, I immediately noticed a decrease in reception quality since I was not able to incorporate the rear antenna. To defeat this, I turned both front fender antenna and rear diversity antenna into one big antenna! Here’s what I used:

1. METRA 40-UV43 Motorola Antenna Y-adapter = $8 from Amazon

2. Scosche Mda-B Micro/Delco = $5 from Amazon

The Y-adapter has two standard size female plugs going to one standard size male plug. The Scosche Mda-B micro adapter converts the smaller rear glass antenna into a standard size antenna plug.

Step 1: Locate the stock 2 antenna plugs from each antenna.

Step 2: Plug the smaller rear antenna plug into the Scosche adapter.

Step 3: Plug the Scosche adapter into one of the Y-cable’s female plugs. Insert the front fender antenna plug into the other Y-cable female end.

Step 4: To finish, just plug the Y-adapter’s single plug into the back of your aftermarket receiver.

The Metra 40-GM10 GM Antenna Adapter (pictured below) works just as good as the Scoshe adapter, but it’s more expensive and roughly 10 inches long. It was on Amazon for $12. I bought it to try it out, but since the Scosche adapter works just as well and is much smaller, I’ve since returned the Metra adapter:

After combining both front and rear antennas into one, I installed a switch in the dash (below the receiver itself) that gives me complete control whether to raise or lower the front antenna mast independently of the receiver. (It’s basically just a switch wired inline of the antenna mast power wire that will either break current to lower the mast or send power to it to raise it.) With the receiver on, I can press the switch, which breaks current and the mast lowers. I can leave it down and still get great reception as the rear glass antenna is now active similar to the stock Toyota setup!

 I leave the front antenna mast down 99.9% of the time. Great for when you’re driving on trails with low hanging branches and listening to the radio without tying up your smart phone and experience no loss in reception quality. Now you don’t have to worry about constantly breaking the antenna mast again!

Installing this Y adapter may not be the correct method to fix this diversity antenna issue with an aftermarket receiver installed in your 4Runner (a lot of people have told me it either “wouldn’t” work or “shouldn’t” work), but it works for my setup and I couldn’t be happier with the outcome.

Check out the forum thread for more information and discussion on this project.

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