I have a Pioneer DEH-P3900MP and I gave it to my bro who installed it in his 05 Hyundai Sonota and when he was wiring it up he use pliers to cut all the cables off the stock wiring harness and he said that all the wires touched for a second when he cut all the wires so it made a spark, but after he got it all wired up it was working. He then screwed it in and put everything back together and the HU wouldn't play any sounds even though it was powered on and the volume was all the way up. He replaced the Audio and Clock fuses with new ones and there is still no sound. What could be the problem for why there is no sound?

Edited August 27, 201015 yr by Crash

:FACEPALM:

The harness adapters are only a few dollars, why on earth didn't you make sure he bought one. I'm not familiar with that vehicle at all, but chances are it has a factory "amp" hidden somewhere and it's now fried either due to getting 12v run through it or too high of an input signal because of the amp built into the aftermarket HU. That would be my guess. They make harness adapter's that for connecting the HU to the factory wires and in the case of vehicles with factory "amps" a bypass harness for those. Try hooking a speaker directly up to the output of the HU, not through the factory wiring and see if it still plays. If so then there's something in the chain of the factory stuff that's bad, if it doesn't then something happened to the internal amp of the HU.

or perhaps he didn't heatshrink/tape the wires good enough and something's shorting out?

We did try getting a wiring harness but none of the local stores by us had any harnesses for his year/model of car. I will tell him to try plugging in a speaker directly to it and see what happens.

Does the car have premium sound? If so, hooking up speaker wires from the head unit to the factory speaker wires won't work, because the factory wires are just signal wires to the factory amps, and they usually need a low-level signal. Speaker wire outputs on an aftermarket head unit are high-level.

If plugging the factory speakers straight to the head unit with new wires works, that's the problem. By running new wires you'll be bypassing the factory amps.

It will only emit sound through the speakers if only three are hooked up, whenever we wire up a fourth speaker in his car, it doesn't play any sound at all. BUT he wired up three of the stock speakers and wired in a aftermarket speaker as the 4th and it played sound through every speaker. Why would it do this?

Try doing the test with the 3 factory speakers and the one aftermarket speaker again, if the system plays then switch one of the three working factory speakers out with the one sitting to the side to rule out a bad speaker causing a problem or it being the factory setup itself.

I have seen this happen in a boat before. You have a short somewhere in the wire to the speaker that will not play or the speaker is bad.

I have seen this happen in a boat before. You have a short somewhere in the wire to the speaker that will not play or the speaker is bad.

What he said. I had a truck in last week, and the radio would go into protect protect because the speaker was reading damn near a dead short. Check the speaker.

And NEVER cut more than one wire at a time when wiring is live. Just presents the possibility of more problems than you need.

Ha. I was messing with my headunit wires the other day with my car on (forgot it was on ), and my 12v made contact with some other wire on the harness, and my whole car shut off and made a loud thump. Scared the shit outta me and I thought i blew my headunit. Luckily i didn't, or any fuses actually.

But yea you probably have a short somewhere. Seems like the only obvious reason.

Edited September 1, 201015 yr by hatrix