Adding AUX to 88-94 Stock Stereo

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Triplel40

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My apologies if this has already been posted, but after finding multiple started threads that dead ended I decided to do a proper write-up on adding AUX to 88-94 stock stereos, both on models with and without a tape deck.

For this addition you will need:
~wire (I purchased a few feet of 18ga multi-connector cable, cut the outer insulation off, and pulled out the individual wires.)
~3.5mm headphone jack
~Switch
~5 wire connector (optional)

My electronics store also had a 3.5mm jack with a built-in switch that closed when the cable was plugged in, which you could use instead of an individual jack and switch, but I prefer to leave my aux cable plugged in even when I'm listening to the radio so I opted for a separate switch.

Installation without tape deck/EQ

If your truck isn't equipped with a tape deck you will need to source a wire harness from a tape player. Best source for them are junkyards. Unplug it from under the dash and cut the wires close to the cassette so you have more wire to work with.
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EQ models will have 9 wires total, I'm not sure how many the tape-only models have but the plug is the same. Here is a diagram and the 5 wires you need.
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Since you don't need the extra wires, you can de-pin the connector by removing the red clip and pushing them back through the larger hole above the pin, using a small nail or stiff paperclip. They are stiff so you have to press pretty hard, once the pin moves a little you can remove the nail/paperclip and the wire will pull out easily.
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Here is the finished result. (I accidentally broke the small black wire [left audio] so I replaced it with a a white wire)
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Now figure out where you want to mount the components, cut the wires to length, and route your wires to the switch and jack.
Blue--------switch side A
Orange-----switch side B (mine in the pictures is brown because I didn't have any orange wire to extend it)

*********----Jack ground
Small black--left audio on jack (mine is white in pictures)
Red---------Right audio on jack

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You should solder the wires to the switch/jack once you verify that everything is working correctly.

SUGGESTED/OPTIONAL

Depending on where you plan to mount your jack/switch, I suggest getting a connector to put inline. I mounted mine to the trim below the heater controls, and without a connector I would have to remove the plug/switch from the panel every time I needed to take off the trim for something. With a connector behind there I can leave everything on the panel, pull it out a little ways, then unplug the connector to remove the panel. Any 5plug connector should work, I would suggest going to a junkyard for these. The one I used was from an overhead console in a Mercedes M-class. Just splice it into your wires near the switch/plug. (More pictures of this towards the end of the Cassette/EQ section)
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Installation with Cassette/EQ

Installation with a cassette/eq in your truck is pretty similar, except you will be splicing into the existing wires instead of starting fresh.

While probably not the best way to do it, when splicing into existing wires I prefer to strip a small section of insulation off of each wire, wrap the new wire around it, then solder them together. This can be done by cutting the insulation in two spots with wire strippers then carefully peeling the insulation off between the spots with a sharp knife. I still suggest temporarily de-pinning the wires you are going to be modifying as it makes it much easier to work with than when they are all together.
Stripped
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Wrapped and soldered
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And here is all of them spliced and heat-shrinked. (didn't heat shrink the ground, as it isn't even insulated past that point. Also, I used Brown for the Orange wire and Green for the small black wire because that's all I had at the moment)
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I ran these new wires the length I needed to reach my mounting location. Use some rubber hose or split loom to keep the wires contained so they are easy to manage. Then I soldered my connector to the end. The other half of the connector I attached to my switch and plug, making sure to keep the wires straight through the connector.
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Here is the finished product.
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With the switch on, the head unit automatically switches to "cassette" mode and plays your aux. Switch off returns to normal radio mode. Cassette player still functions as normal. IF YOU HAVE A CASSETTE IN AND YOUR AUX PLAYING YOU WILL HEAR BOTH INPUTS, so if you want to use your aux you have to have the Cassette ejected.


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Being a manual I opted for an aux cord with a 90 degree plug on one end, so the cord drops down instead of sticking out towards the shifter area.
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Enjoy!
 
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curtmush

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Yep. Definitely going to attempt this. Tired of reaching over to adjust the radio, not impressed with my cheap-o aftermarket radio/bluetooth phone capabilities, and my color match paint job didn't match. (My OCD flared up so bad, I haven't even reinstalled it.) Thanks for the well written how-to!
 

Eveready

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Nice job. I wish someone would write up the procedure for replacing the power supply capacitors in the stock amplifier unit (the part mounted above the accelerator pedal) which is what usually craps out in these radios. I went aftermarket and I really enjoy the bluetooth capability but restoration of the stock radio would be a good goal for someone attempting an authentic full restoration.25 year old capacitors WILL crap out, so if you go this route you should be prepared for it to happen.
 

Eveready

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Is this possible for the 95+ radio? If it is, is the procedure similar? Anyone know of any threads?
Nice writeup though. I like mods like this.

If he is using the cassette player harness it should work exactly the same . If cassette or CD players were offered with the 95+ radio then the procedure should be identical.
 

Cheap Heap

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Awesome write up, I've been meaning to search for this.

I'm assuming you could also play a blank tape instead of using the switch?
 

Triplel40

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Thanks everyone. Just figured I'd share since it isn't too hard to do. I have a couple of spare 89+ cassette players and harnesses if anyone is interested in one I'll ship them out, keeping the 88 spares for mine though.

Is this possible for the 95+ radio? If it is, is the procedure similar? Anyone know of any threads?
Nice writeup though. I like mods like this.

This thread is for 95+. It was a repost of a thread from the LS1tech forums about 98 Camaro radios, but they are the same radio as the trucks so between the two you should be able to figure something out.
http://www.gmt400.com/threads/adding-aux-input-to-obs-stock-radio.198/

Awesome write up, I've been meaning to search for this.
I'm assuming you could also play a blank tape instead of using the switch?

Yes you could, but you would be running the tape player for no reason. I'm thinking you could actually use a normal cassette and just fast forward it to the end, unless these players auto-reverse. I'm not sure as I haven't gotten the chance to use it much. My truck originally didn't have one so I built the stand-alone aux plug with a switch, then happened to find a 1988 specific eq/cassette so I started swapping everything over. Still missing the mount for the rear of the player so I can't install it yet, will be headed to the junkyard tomorrow to grab one.
 

DerekTheGreat

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I'm looking to do this to my '89, however, I'd like to do things a bit differently so I've got a few questions I was hoping you guys could help with..

I don't like dip switches nor does the thought of running two cables (3.5mm & charge) get me excited.. Instead, I'd like to wire up the Aux switch to say a cargo lamp switch for a more factory look and then wire in a USB switch so I can run just one cable to my ipod. Has anyone done this? I assume I need a resistor to drop the voltage coming into the USB port to 5v? That aside, I figure I just need an accurate wiring diagram for the standard 30 pin Apple connector and just make the proper splices but I'd like confirmation to know if it is straightforward like that.

Looking at the diagram for a standard 30 pin Apple USB connector, it shows pins 1&2 on the USB connector lead to pins 25 & 27 on the 30 pin Apple connector which are labeled as "USB Data Negative" and "USB Data Positive" but would those actually send an audio signal or not when plugged into my Ipod? Seems all I have to do is splice pins 1&2 of the USB connector into the small black & red wire like depicted in the write up and then presto, I've got a USB input instead of a 3.5mm input. I'm hoping someone can confirm that because then I'll start ordering parts. I picked up an EQ tape deck radio at a boneyard this past Monday, I'll be testing it tonight and then if it checks out, I'll begin doing the mod..

Thanks for the help fellas!
 
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