Adding AUX to 88-94 Stock Stereo

[cngodfather]

I have already swapped out my radio. However, I love this type of retro engineering. I applaud you sir!

 

[Donald Mitchell]

I am willing to do a write up on fixing the 89 style radio box. I have read that it is a capacitor problem but do not know which is the correct part. Anyone know which it is from the pictures?

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Heres the caps the microfarad, or Uf in on the label is the capacitance along with the voltage rating. You can go higher on voltage but the physical size usually increases, so be sure to check the clearance around the cap before ordering. Nichicon, Panasonic, United Chemicon, Vishay, Sprague, all good replacements. No names, you take a chance.

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[DennysGarage]

Has anyone run into this plug on your equalizer? Been gathering restoring a 1992 GMC C1500 SLE and ran into this. I set the project aside and didnt pay attention. Now looking at my wiring....its nowhere similar. So if anyone has a plug schematic for this that would be much appreciated if not, what about a link to a database of plug schematics. Thanks

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[AK49BWL]

That plugs into the CDM under the dash to the right of the accelerator, supplies power to the deck and sends audio to the CDM. Also on the back of the deck is a white connector, you need a 2-wire connector from the stereo head to plug in there for the EQ to work.

Check this thread out, it may help: https://www.gmt400.com/threads/88-94-factory-stereo-info.48716/#post-1095914

The wire colors may be different to the cassette player for certain years, but ALL of the wires perform the same functions and the decks are interchangeable between 88-94.

 

[Carey S Turner]

Because I want to preserve/restore the cassette player in my Sierra for new Retro Wave Cassette tapes, this is the exact post I needed.

 

[351FUN]

So how would I wire this up if I didn't want to retain the tape player capacity or even radio? I just want aux in all the time. Truck is a 92 with factory tape deck.

 

[Triplel40]

So how would I wire this up if I didn't want to retain the tape player capacity or even radio? I just want aux in all the time. Truck is a 92 with factory tape deck.

Pretty much the same as the original post without installing the switch. You would just permanently wire pins #11 and #12 (orange and dark blue wires) together instead of using the switch to turn them on. If you don’t care about it you can just cut the original harness going to the tape deck and install the aux plug onto the end of it and wire those two together.


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[ht89]

Here's my rig using the same switch and jack in post #1.

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[Triplel40]

Here's my rig using the same switch and jack in post #1.

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Looks good! That switch and jack location looks like it works great! Kind of wish mine was down there haha. Glad to see this thread is still helping people.

 

[1C9A8A0]

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!

Lance, thank you so much for posting this. Here in 2021 I’ve decided to do a Bluetooth adapter instead of an aux jack. The adapter has two RCA’s plus a 12v+ and a 12v-.

On the power side will I just tie the 12v+ to tape in/load side of the switch and put my 12V- to the H-Grd side of the connector?

I’m doing this in my 94 C70 Kodiak with no tape deck but all this appears to be the same.