I purchased a Metra wiring harness to use the stock amp-speakers for an aftermarket HU and recieved it last night. So I got my Kenwood DID installed but I'm getting a lot of ENGINE NOISE. Is this due to a bad ground? There's color codes on back of these packages that Metra supplied. I followed the chart, wired every wire but I'm questioning where does the blue/white(amp turn on) wire go? I moved it around to ACC then to Constant 12V, engine noise still there. The HU works fine, its just the engine noise is really loud.. I see that theres 4 plugs behind the factory stereo but Im only using one.. Should I order the other plugs? I called installer.com where I got the kit and they told me that I wouldnt need it. Any suggetions, I beleive it has a factory Pioneer Hu cause its a 92 if that matters..

Heres the kit Im using

http://www.installer.com/item/displa...php?it=70-8112

 

You shouldn't need to connect the turn on wire, nor would it cause noise.

My suggestion - try unplugging the RCA's that are in the harness. If the noise continues, it's the amp. If the noise is gone, it's the deck. Change the ground to a better location than factory. Let us know what you find.

Big Mack

 

Ok, so I relocated the ground from my HU and the noise is still there but its much quieter. Couple things Im not understanding. If I dont need to connect the "AMP turn on wire", how would the AMP WORK? And if I disconnect the RCA wires from the harness, how would I be able to hear anything?

 

If you're hearing something right now, the amp is working. If that wire is not connected to anything, yet you're hearing sound, where is the question?

It's troubleshooting - you're eliminating one component or the other to rule it out from being the source. Remove the signal, and if the noise is present, it's downstream.

Big Mack

 

two problems typically cause engine noise - unmatched inputs on rca cables, which is possible with the aftermarket radio and factory amp, and a ground loop problem...

two ways to potentially solve it, first is to find a good ground... kinda tough behind the dash, but it can be done... second is to buy a ground loop isolator (it's essentially a small box with rca inputs and outputs... put this inline behind the head unit...

the other option is to bypass the factory amp completely... good chance your new head unit is more powerful anyways...

 

according to my wiring diagram, the green wire behind the head unit is the power turn on lead for the amplifier... also from this diagram, it appears that this is the same wire that energizes the head unit itself... so, from this, it looks like the green wire comes from the key on position and splits to go to the head unit and the factory amplifier probably at the connector right behind the head unit...