Installing New Car Stereo


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Old 04-29-21, 04:48 PM
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Installing New Car Stereo

I bought a new stereo for my old pickup truck, 1991 GMC Sierra. I removed the old stereo, then started installing the new wiring harness. I forgot to disconnect the battery, needless to say, I had a couple/few sparks when I started moving the wires around. I disconnected the battery, and went back to installing the new stereo. When I completed the install, there's no power getting to the unit. I checked the fuse, it's good. I don't know squat about wiring and don't want to pull the dash to try and figure out what's going on. I assume the speaker wires are all still good. I want to bypass the Red, Yellow and Black wires. I picked up a couple of fuse tap leads. I know I need to run the Black wire to the firewall or some other ground. Red wire (Ignition) and Yellow wire (Battery) is where I'm not 100% sure. Can I run the Red wire directly to the Ignition fuse on the fuse box using the fuse tap? Where do I connect the Yellow (Battery) lead on the fuse box?
 
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Old 04-29-21, 05:02 PM
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If the wiring is still good...... find the problem.

There are two fuses to the radio. One is always live to hold the clock and memory.
It's usually a 10A fuse and is combined with other always live devices like dome light, map light, glove box light, etc. This protects the yellow wire.

The other fuse comes on in ACC mode.
This protects the red wire.

One fuse will be under the hood.... I believe the always live one and the other is in the side of dash fusebox.
 
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Old 04-29-21, 05:06 PM
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Did you cut existing connector to splice new connector on?
Usually, it is best to get a adapter cable and don't touch original wiring or connector. Also, no need to disconnect battery.

It is very unlikely you will damage wiring by short because everything is protected with fuse. You should have blown the fuse if you had a short.
Did you actually check voltage with a meter?
Are you 100% positive you wired your harness correctly?

Where you can tap with a fuse tap will depend on the vehicle. You will have to figure out which fuses are switched with ignition and which are always hot using a tester (a simple continuity tester or multimeter).
 
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Old 04-29-21, 05:21 PM
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The new radio came with a wiring harness that had to be connected to the ends of the old wiring harness. Ordered through Crutchfield, they do an excellent job of providing everything needed and great phone support. I'm fairly sure I wired it correctly. I went so far as to rewire the old one to see if I had power, it was a no go.

I assumed the same, the fuse would go bad before wires melt. I did not look under the hood for a compromised fuse. I'll try that. I'd prefer to use everything as is assuming I can determine the problem.

I didn't use a volt meter, but I did use one of those low voltage detectors (lights up when passed over power). It seemed to be hit or miss, but I'll use a volt meter instead.

Thank you both for your suggestions.
 
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Old 04-29-21, 05:47 PM
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It was a 20 amp fuse. I didn't bother checking anything above 10 amps, so I missed it. Thanks for the input. Replacing the fuse was much easier than the alternative.
 
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Old 04-29-21, 07:26 PM
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It is best to adapt existing wire harness to new radio harness using connector like following link

https://www.amazon.com/Scosche-GM02B...9749288&sr=8-3

You don't have to mess with factory wiring and easy to revert or change over to different radio.
Also, wire color usually matches with the one comes with radio making it even easier.
Crutchfield should carry similar wire harness as well.
 
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Old 04-30-21, 04:56 AM
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It is very unlikely you will damage wiring by short because everything is protected with fuse.
But still possible! The harness for a new radio a friend was installing beat me "severely about the head and shoulders" for most of a weekend. I found a blown polarity protection diode in the harness. No mention of it in the paperwork.
 
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Old 04-30-21, 06:49 AM
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ThisOldMan, I think mine would have become a most of the weekend thing too. Glad it was just a 20 amp fuse. Was too dark to complete the install and put back some of the panels I pulled off looking for a problem, but my mood improved instantly, LOL.
 
 

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