Big problem that does’t make sense, deck

Hi everyone, i'm going nuts ! I've been trying all night to figure out what is wrong with my buddy's system. (Pionner DEH7600MP, MTX RT202 amp) The problem is that his "sub out" is going wacko: pops and rumbles when turning on and changing tracks and sounds like a bunch of rumbly messed up bass. I have tried everything, litteraly, to find what is causing the problem. Here's what i tried: Diffrent RCA wire - same thing - RCA wire not the problem Diffrent source (from my deck inside my car) works perfect - amp not the problem Put his deck in my car - works awesome - his deck is not problem Put my deck (DEH5500MP that works 100% in my car) in his car - exact same problem, problem defenetly not his deck Tested all wires with meter - Everything normal when on and when off (ON:yellow 12v, red 12v, blue 12V - OFF:yellow 12v, red 0v, blue 0v) Grounded the casing of the deck - nothing changed Tried a diffrent source for the turn on lead for the amp - same cut the harness and rewired it - nothing changed cut the power wires (yellow red and black) from the harness, connected the yellow to a wire coming directly from the battery, the red connected to a acc relay that i just installed and the black to a nice solid bare metal ground, and with the rest of the harness NOT connected in case speakers were interfering - results....same damn thing ! --------------- Speakers connected to deck works perfect rear RCA out WORKS front RCA has that problem sub out, the same Deck show no signs of malfunction Remember that both decks work 100% in my car and has exactly the same problem in his car ---------------- His car, 90 prelude my car 98 corolla --------------- If someone could help me out with this, it would be greatly appreciated. Thanks for your time - Nick

Try regrounding the deck and the amp. Also you said its a popping noise right? Find out if it happens with the car running and also when its just sitting there with the ignition on. If it is only with the car running it could be the spark plug wires. A bad connection or a pin hole in one of the wires can cause a popping noise when runnning an amp.double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

im thinkin gain too...Canadian Auto Sound

Starting Installer

I greatly appreciate the help everyone but it looks like there's a few things in my first post that has been not been looked at. When i was rewiring the deck, i had the deck on my lap with the harness streched out attached to it. I also tried moving around the harness to see if it had any affect, nothing changed It's not a gain issue, when i connect the rca from my car's amp rca output to his amp rca input, the gain behaves normaly. When it's connected to the deck inside his car, if i turn the gain beyond 1/4 there's some sort of feedback (basicly a loud constant humming rumble). The poping noise is not "thump", it's like a series of soft "pomp pomp popopomp" when the deck is working (reading the cd) it's not loud at all but still an indication of a problem. could it be the amp's grounding somehow interfering with the deck? The only thing that seems to work is when i connect my deck which is entirely from a diffrent electrical system which it could not interfere. Does this make sense?? The amp in his car is solidly grounded on a bare metal surface. Today i'm gonna try to connect the deck straight to the battery see what happens. I'll post the results. Please look clearly at my first post before replying Thank you very very much for your input everyone. I greatly appreciate it.

oh, sorry i forgot to add this happens with the car off or on. doesn't change

The symptoms you describe in the post above indicate your amp gain is too high. Plus I suggest NOT using teh factory ground for the HU but connect the HU ground wire directly to the chassis.Support the12volt.com

I strongly believe that it's not the gain, when running from my car, the deck works perfectly on his amp. I can turn up the gain to a resonable level w/o any defects or feedback. Also, i don't understand why the rear RCA out works but the front RCA out and the sub out has that problem. In my first post, i indicated that i ditched the farctory harness all together: "I cut the power wires (yellow red and black) from the harness, connected the yellow to a wire coming directly from the battery, the red connected to a acc relay that i just installed and the black to a nice solid bare metal ground, and with the rest of the harness NOT connected in case speakers were interfering - results....same damn thing ! " There's something in the electrical of his car that i just can't put my hand on. I'll try a few things today and post them. Thanks !!