1990 gm c1500 pickup radio diagram?
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Forum Name: Vehicle Wiring Information & File Requests
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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=106080
Printed Date: May 12, 2024 at 7:42 AM
Topic: 1990 gm c1500 pickup radio diagram?
Posted By: huser246
Subject: 1990 gm c1500 pickup radio diagram?
Date Posted: July 12, 2008 at 7:25 PM
I've got the three components out of a 1990 C1500 Chevy truck, want to know if anyone has the complete wiring diagram? The radio has 3 parts, the amp, the radio, and the tape deck. I want the wiring diagram for the wires between the tape deck & the amp, and the radio & the amp. Need to know which wire(s) is the the trigger to make the amp switch from the radio to the tape deck. Thanks.
Replies:
Posted By: i am an idiot
Date Posted: July 12, 2008 at 7:45 PM
Do you have the units powered up and playing? It has been a long time since I worked on one of these units, but I think that there is a wire that goes to 12 volts when the cassette deck has a tape in the deck. You should be able to find that wire using a volt meter.
Posted By: huser246
Date Posted: July 12, 2008 at 7:50 PM
Yes, they are connected & working right now. So it will be +12 volts when the tape is inserted, and no voltage when the tape is removed? If that's the case, that'd be great & easy to find. Thanks for your help.
Posted By: i am an idiot
Date Posted: July 12, 2008 at 8:01 PM
That is how I remember it. There are not many wires on that plug. Take a voltage reading on every wire with the tape out and then insert a tape and have it playing, recheck the voltages, and see what changed. What are you trying to do? Ipod inputs?
Posted By: huser246
Date Posted: July 12, 2008 at 8:32 PM
Yeah. I've had the radio a long time mounted in a cooler on a boat. Don't really use tapes any more (heh, since 1990), and I figured if I could make the amp switch to the aux input it would accept the input from a mini-phono jack. Speaking of which, any suggestions on how I would identify the audio wires from the tape deck to the amp? Thanks again.
Posted By: i am an idiot
Date Posted: July 12, 2008 at 8:45 PM
Set your meter to the AC Volts function. With a tape playing in the deck, you should get a low voltage reading on 2 of the wires. To verify that they are the correct wires, wait till a the blank spot between songs. The voltage will drop at the blank and then go back up when the song starts. Look at the plug carefully, they may be inside of a shielded cable.
Posted By: huser246
Date Posted: July 12, 2008 at 8:55 PM
Inside the wire bundle, there is a 3 wire shielded bundle. It has an insulated white, insulated red, and bare black. Think that's +left, +right and -common? I was thinking that was power, but like your suggestion above, I guess that would be easy to test. I'll take some pics and post results when I'm done, if it's successful. Thanks again.
Posted By: i am an idiot
Date Posted: July 12, 2008 at 9:36 PM
If it is in a shielded cable, that would be the audio wires. There is no need for shielding on the power wiring.
Posted By: huser246
Date Posted: July 12, 2008 at 11:33 PM
Got it, it was the brown wire. Supplied +4.88 volts when the tape was inserted, 0 when the tape is ejected. Should be simple now. Short out the switch inside the tape deck, and put a switch in the brown wire. Then wire a mini phono plug into the 3 wires in the shielded cable, and splice a 12 volt cig-lighter plug into the switched 12 volt supply wire. Gotta find a plastic box to put it in now, maybe a cheap plastic toolbox. Has to big enough to hold the radio parts & a lawn tractor battery. I'll bookmark this page and post pics when it's done. Thanks for your help.
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