Wiring color code Woes
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=15685
Printed Date: July 16, 2025 at 9:32 AM
Topic: Wiring color code Woes
Posted By: chabat
Subject: Wiring color code Woes
Date Posted: June 30, 2003 at 8:05 PM
I have a '92 Trooper "S" 3.2L SOHC and I looked up the stereo harness color codes on this site under "general info - Vehicle Information". It listed the colors, but they are not even close to what in in my factory harness. Where can I get a good list/diagram? Could it be that this site's info is incorrect because there is an "S" model and an "LS" model Trooper for 1992? The problem I am having is that I bought another Isuzu Trooper factory radio off ebay and of course the wire colors on the adapter are totally different than what is in my '92. My whole purpose is to sell the vehicle, so I was trying to invest a minimum amount into the radio. I got it powered up and no matter how I hook up my test speaker, no sound comes out. I guess the internal amp could be bad... Any ideas???
Replies:
Posted By: esmith69
Date Posted: June 30, 2003 at 8:55 PM
If it turns on fine, retains presets/time after the car is turned off, but just doesn't have any sound output, then either a speaker wire is shorted out somewhere, or a factory amplifier in your vehicle is not getting the proper turn-on signal necessary. Given your situation i think either one is a possibility, but most likely it's a shorted speaker wire due to improper speaker wiring. If a speaker wire touches the metal chassis of the vehicle, or is accidently hooked up to a ground wire, then the head unit will still appear to function normally, it will just not output any sound. If you still have the factory plug attached to the end of the wiring harness that's built in to your vehicle, you should try looking at both of these isuzu harnesses (70-1762 & 70-7712), keeping in mind that 1) these are the male ends of the plugs, not the female ends like those that are present in your vehicle, and 2) the coloring of these two harnesses follows the EIA standards for color->function. And then just hook up to the new isuzu stereo accordingly. As always, keep in mind that it's best to verify wires with a multimeter before you actually connect to them. ------------- Ethan
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Posted By: chabat
Date Posted: July 01, 2003 at 1:14 PM
The factory speaker wire is at issue because I am using a test speaker that was verified to work woth another radio. As to the second possibility... I hooked up 12v+ to the white wire and the red wire with yellow stripe. The display lights up and the tuner will find stations, and the casette player will Reverse, FF, and play a tape, but no sound. Isn't there usually just a constant 12v+ for memory and a second switched 12v+ for the radio? Should there be a 3rd switched 12v+ for the amp alone? Chris
Posted By: chabat
Date Posted: July 01, 2003 at 1:16 PM
Whoops, I meant: The factory speaker wire is NOT at issue because... Chris
Posted By: chabat
Date Posted: July 01, 2003 at 1:23 PM
Also, Neither the Harness Connector which is still intact (Uncut) in the Vehicle, not the Harness connector which is attached to the radio (with cut wires) --- Neither of these have wires matching the colors on the EIA Standards OR the chart found on this site for my year of Trooper. That is why I asked if they have different color wires for different models of Troopers like the S model vs the LS model? Can't the internal amp have simply failed? Chris
Posted By: esmith69
Date Posted: July 01, 2003 at 1:25 PM
If the head unit you're installing came out of a vehicle that had a factory amplifier, than most likely the head unit outputs its own remote turn-on signal that is intended to be used to turn on factory amplifiers. Unless the vehicle came with a factory amplified system though, the head unit will probably not have this kind of output. Now if YOUR vehicle originally had a factory amplified system in it, you'd have to figure out which of the wires in your vehicle's wiring harness is the amp turn-on wire, and then connect that to the same +12V switched wire that turns on the head unit. The switched connections use very little current and that's why you can hook up more than just the head unit, to a single +12V switched wire coming out of the vehicle's wiring harness. Then again, if the head unit you got from another vehicle was meant to be used with a factory amplified system but your vehicle was not, then you may have problems no matter how you wire it all up. That's because most head units that are part of a factory amplified system only ouptut a low-level signal that, by itself, is not enough to power speakers. If you were to hook it up to wiring in a vehicle that does not have factory amps, you would most likely get no output, or poissibly when it's turned all the way up you might hear a very faint amount of sound. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: chabat
Date Posted: July 01, 2003 at 1:32 PM
Also I looked at the pics of those two harnesses :( 70-1762 & 70-7712) and those colors don't match either of my harnesses either. Chris
Posted By: chabat
Date Posted: July 01, 2003 at 1:37 PM
I see exactly what you are saying. The head unit I bought -- I do not know if it was using an external factory amp. I figured it did not since it was a low end isuzu (clarion) radio w/cassette player. But since I do not know what year model of Trooper it came out of, I guess I will never know. Chris
Posted By: chabat
Date Posted: July 01, 2003 at 3:17 PM
With the model number printed on the radio, is there a way to find out if it is internally amplified, or anything else about the radio for that matter? Clarion PI-9993M Cassette Player
Posted By: esmith69
Date Posted: July 01, 2003 at 6:00 PM
It's probably one that came with a vehicle with a standard stereo system. In other words, it has its own built-in amplifier, and it's designed to hook up directly to the factory speaker wiring in the radio's harness. Using those plugs in the pics, were you able to figure out the functions of each factory wire? Or was the original plug in your vehicle already cut off? ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: chabat
Date Posted: July 01, 2003 at 6:20 PM
Can I post a pic of it showing what I found? On the vehicle wiring harness I have identified which wires are 12v+ constant and 12v+ switched as well as the speakers. On the radio itself, that is where I was having trouble because the colors of the wires do not match any diagram I have found. How could you test the internal amp to see if it is putting out any signal to the speaker?
Posted By: esmith69
Date Posted: July 01, 2003 at 6:34 PM
When you got this used isuzu radio, did it come with the plug that goes into the back of it? Or did they just give you the stereo itself without anything to plug into the back of it? ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: esmith69
Date Posted: July 01, 2003 at 6:41 PM
oops sorry I forgot to answer your question about testing the speaker outputs. First you'd have to find a pair--that is, the positive wire and the negative wire for the same speaker. Then, with the system turned on you test for voltage by putting the red test lead on one wire and the black test lead on another one. Positive voltage means the wire touching the red test lead is the positive speaker wire, and negative voltage means the wire touching the black test lead is the positive speaker wire. Now the only problem with this is that even if it outputs a low-level signal, it will still show up as voltage, just not as much. It really varies from vehicle to vehicle and stereo to stereo so I don't know of an exact number to look for. One thing you CAN do that might be easier for you, is to get a test speaker and put that in place of the multimeter leads. If you can just barely hear sound coming out of the speaker even when it's turned way up, then the head unit is outputting a low-level (un-amplified) signal. If you can easily hear the sound then you'll know right away that the head unit has a built-in amp and is outputting a high-level (amplified) signal. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: chabat
Date Posted: July 01, 2003 at 7:08 PM

Here is a pic of what I have, I did try what you said with a test speaker and no sound came out.... Chris
Posted By: esmith69
Date Posted: July 01, 2003 at 8:05 PM
For the test speaker thing the only wires that should be connected would be constant power, switched power, ground, and two speaker wires running directly to the positive and negative terminals of an external test speaker. All of the other wires should be taped off individually, so as not to touch each other or the vehicle's chassis. The antenna you should plug in cuz you'll need to get radio reception to have sound to test with. You may have to turn the volume all the way up but even on a head unit with only low-level outputs you should still get sound (albeit very faint) coming out of the test speaker. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
Donate to the12volt.com
Posted By: chabat
Date Posted: July 02, 2003 at 8:20 AM
I tried all that. I appreciate everyone's responses to help me. I do believe she dead. Thanks Ethan. I don't guess it is even worth messing with anymore, huh? Chris
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