Installing new head unit. Need help!

[alfredhybrid]

I'm installing a new double din JVC head unit with nav, dvd, bluetooth, etc.

I have it all wired up, but it's acting flaky. The big problem is that there is an awful hiss through the speakers. I'm using the factory amp and the hiss starts as soon as the amp gets power from the head unit, even if the volume is all the way down. In fact, it's there even if the speaker wires aren't connected at the rear of the head unit.

I've plugged in the old, stock head unit and the hiss goes away. I've also tried grounding to the chassis, negative terminal, etc. and the hiss gets better, but doesn't go away. When the engine is running, the hiss follows the revs.

What's going on? Should I try to bypass the stock amp?

 

[CappyKD]

Bypass the stock amp. sounds like a ground loop.

 

[Brock]

the hiss through amp is normal...mine does it from power with volume OFF but once I get volume up higher I dont notice as much. Told that I would have to replace or bypass factory amp to get rid of it...as we already did the filters and had no effect.

it is a very low volume hiss...more like background hiss...if yours is loud or very prevalent...then a wire is crossed I bet.

 

[LTrain0800]

Funny I have a hiss like that as well. Thing is it goes away completely when I switch to cd! I have a Kenwood DDX6019 head unit playing through the stock amp. I would love to figure out why this is...

 

[Sandroad]

You might try running through the Crutchfield noise suppression guide:

http://crutchfield.custhelp.com/ci/fattach/get/19/

 

[re_guderian]

Check out my thread on my Kenwood DNX install here. Get a ground loop isolator from radio shack, but you'll need to find out which component is causing the problem. It is curable, and no need to bypass the stock amp.

 

[alfredhybrid]

I tried to isolate it before my original post. I had the power (switched and unswitched), ground and amp power connected, nothing else. The speakers still hissed. Not sure where I'd connect a ground loop isolator.

New information. It hisses when I turn it from off to accessory. Hisses more when I turn it from accessory to the engine running. However, when I turn the engine off to accessory, no hiss. How's that?

 

[RobRed]

Guys the hiss is a input impedance issue. The Toyota amp is non- standard. The only way to get rid of this problem is to get rid of the OEM amp.

 

[Sixgunz]

Guys the hiss is a input impedance issue. The Toyota amp is non- standard. The only way to get rid of this problem is to get rid of the OEM amp.

x2 The stock amp is not jiving with the aftermarket head unit.

 

[alfredhybrid]

If so, why does it work perfectly when I turn the engine off but leave the ignition in accessory?

 

[RobRed]

If so, why does it work perfectly when I turn the engine off but leave the ignition in accessory?

Then we are not talking about the same issue.

 

[re_guderian]

Tell us more about your wiring harness adapter to the HU, or maybe a picture? There are a lot of ways for noise to get into the system. The HU is supposed to ground through the amp (stock wiring). Are you stll that way? The ground wire for the stock HU runs through a shielded bundle.

 

[Sixgunz]

If so, why does it work perfectly when I turn the engine off but leave the ignition in accessory?

Because when your engine is off, your input voltage to your deck & amp is around 12v - 13v. When your engine is on, it's typically over 14v.

Plus, your aftermarket deck has considerably more output power than the OEM deck. Your OEM amp doesn't utilize RCA jacks..it uses speaker level inputs with no ability to adjust the gains from the pictures I've seen. If it had this, you would a lot more ability to adjust the sound and possibly get the engine noise to an acceptable level....although as the other poster said, the impedence descrepancy between your new deck & OEM amp may be too big to compensate for.

 

[snapaxle]

I used the factory amp and simply added Rca's to the lead wires that go to the amp. Then just plugged them in to the headunits RCA outs. No hiss, no noise, nothing. Amplifying the already amplified signal is pretty sure fired way to get a hiss.

 

[Gottagetone]

Splain how you ran the RCAs off the amp, I am considering one of the double din units off of ebay and that sounds like the best way to install it.

 

[RobRed]

Splain how you ran the RCAs off the amp, I am considering one of the double din units off of ebay and that sounds like the best way to install it.

2x

Simply adding RCA's to the amp shouldn't make an electrical difference unless Toyota is doing something pre-amp between the oem head unit and oem amp.

 

[alfredhybrid]

OK, here's more. Went to the local auidio specialists and explained the issue. They were stumped too. No hiss when in accessory. Hiss when in on or engine running. I bought a Metra 12V inline noise filter. I tried to filter the switched and unswitched power and no change.

Then, I disconnected the amp power lead so theLC speakers would be off. I connected an Infinity Refeence speaker to one of the leads out of the head unit (not the RCA jacks). No hiss. So, amp powered from new head unit, speakers hiss. Speakers powered from new HU with amp "bypassed," no hiss. I'll be ordering the crutchfield amp bypass tonight.

 

[RobRed]

Amazon.com: Metra 70-8116 Factory Amplifier Bypass Harness for Select 2000-2004 Toyota Vehicles with Amplified JBL System: Electronics

 

[alfredhybrid]

Ordered. Should get it on Thursday.

 

[Gottagetone]

Will that cable still allow your sub to work? Will your H/U allow you to control the volume of and power the sub?