Wiring color code Woes

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???

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.

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

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

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.

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?