Print Page | Close Window

tricky hu problems

Printed From:
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
Printed Date: January 24, 2022 at 12:54 AM

Topic: tricky hu problems

Posted By: quicksilvr
Subject: tricky hu problems
Date Posted: November 05, 2011 at 7:38 PM

Hi, here is the issue I have. The vehicle is a 1997 Toyota 4Runner Limited. When we bought it, it had an external amplifier and a single 10" subwoofer installed, and I assume the door speakers were also being powered by the external amp...due to sound quality and clarity at high volume. I was definitely a professional installation, and the factory stereo was retained. So what I have is a very nice sounding system with an amp and a sub, but controlled by the factory stereo (with no modern functionality and the horrible pale green backlighting).

So I purchased a nice Kenwood HU, and attempted to install it today. I made sure a got a HU with 3 sets (6 total) RCA pre-outs, because I didn't know what kind of wiring I was going to run into when I pulled the factory stereo out.

In these 4RUnners, there is a little separate amplifier behind the stereo. Two harness plugs in the little amp, with then one harness plug going from the little amp to the stereo. The stereo also has the antennae cord and a smaller cord that looks like the antennae cord, but I'm not sure what it does.

When I removed the factory stereo, I found the front and rear speaker wire sections of the harness plugs had been cut, and the wires from the plugs ran into 2 separate line converter boxes. The line converter boxes have 2 RCA outs each. THe other end of the cut wires were doubled up together and wired into some speaker wire that also ran towards the back of the truck.

Not sure what to do, I went ahead and attached the Kenwood harness to the adapter harness, just like I would if I was installing the HU into a car with no amp or subs or anything. I wasn't expecting it to work, so I guess I wasn't suprised when I hooked it up, turned it on, and got no sound whatsoever. The HU powers on just fine, but there is simply no sound. When I put the old factory stereo and mini amp back in, just to test again, everything worked just fine. I assume I need to use my RCA pre-outs on the Kenwood, but I don't know where to hook them into, and I don't know where to put the sub out either.

Any help is much appreciated. I know I can do this myself with a little help, so I'm really trying to avoid paying someone else to finish the install for me. THanks!



Posted By: DYohn
Date Posted: November 05, 2011 at 9:46 PM
If you have line converters, they are connected to RCA cables, yes?  Connect those same RCAs to the outputs on the new HU and see if you gat a signal to the amp (and also make sure the amp is coming on.)  By the way, what is the amp and are you certain it's driving more than the sub?


Posted By: quicksilvr
Date Posted: November 05, 2011 at 10:30 PM
WIll do.

I'm not certain the specs on the amp. I will get them, and post them up. And I'm pretty sure it's driving more than the sub, but not positive. I'll take a picture of the amp (and it's wiring connections) so you can see what's happening

Posted By: quicksilvr
Date Posted: November 05, 2011 at 10:50 PM
Also, just had this thought. The factory stereo has no "subwoofer" control. There is simply a 3 band EQ with individual knobs for low mid and high. If you turned the bass up on the factory EQ, the sub got a lot louder.

I think that the signal from the RF/LF and RR/LR is all the amplifier is getting. I'm going to hook those RCA's up to the Kenwood and see what happens. But then for optimum performance, I think I'll still need to run a whole new set of RCA's back to the amp from the "subwoofer" pre-out's on the Kenwood. And I don't know where to hook them into the amp. lol, arg. I think a picture or two of the amp and it's connections will go a long way....

Posted By: quicksilvr
Date Posted: November 06, 2011 at 9:41 PM
I plugged the RCA cables (2 sets) into the front and rear set of pre-out's on the Kenwood. Nothing. The amp doesn't come on. Not sure what needs to happen for the amp to power on. I took some pictures with my cell phone, here they are.

The amp is an Alpine 4/3/2 Channel power amp, MRV-F400. I can't easily lift the amp out of the recessed part of the box where it's mounted, so I can't see the side of the amp where the channel setting controls are. I know that doesn't help, but maybe these pictures of how it's wired will.

Here is the side of the amp that I couldn't get a picture of (web picture)


And here's my actual amp pictures:

Overall right side view

From left to right when looking the ^ side




And the opposite side...this is the best pic I can get, not enough space to get a good angle


Posted By: blanx218
Date Posted: November 07, 2011 at 6:38 PM
The amp is running all the speakers. transfer the rcas from the LOCs to the Kenwood. you can use the front output for one set of rcas and the sub to the other. Your amp has 2 channels running the door speakers in parallel and the sub is bridged on the other 2 channels.

Posted By: quicksilvr
Date Posted: November 08, 2011 at 1:11 AM
blanx218 wrote:

The amp is running all the speakers. transfer the rcas from the LOCs to the Kenwood. you can use the front output for one set of rcas and the sub to the other. Your amp has 2 channels running the door speakers in parallel and the sub is bridged on the other 2 channels.

Thank you!

A couple more questions, and I think I've have it figured out. First, how do I know which set of RCA's to put in the Kenwood HU subwoofer pre-out? Based on which wiring harness wires they are spliced into, I have the RCA's identified as "front" and "rear"...(but no right or left, because the LOC's weren't labeled). And I have them plugged into the pre-outs on the Kenwood HU the same way, front into the front and rear into the rear. Leaving the subwoofer pre-out open....

Second, the amp is not coming on when I key the ignition. I now know that is due to the fact that it's not getting any remote signal to turn on. How do I remedy this? I think I use the P. Control wire. I also see a single blue wire following the RCA's back to the amp, it's attached to one of the harness wire's with one of these:

Do I just need to splice my P. Control wire into that blue wire?

Thanks for all the help. If I can get the amp to turn on, then I just need to figure out which RCA's to hook in where on the HU to get the correct sound control that I want.

Posted By: i am an idiot
Date Posted: November 08, 2011 at 5:00 AM
Connect only one RCA cable to the front output of the deck.  Depending on what speaker(s) play, should let you know which cable it is.

Posted By: quicksilvr
Date Posted: November 08, 2011 at 11:25 PM
Thanks to you guys help, I had success in getting sound tonight! It was fairly easy to figure out which RCA needed to go where by testing them one at a time. Two of them had a full range sound, one was left and one was right. The other two were only low end. I put the ones that made low end into the "subwoofer" pre-outs, and I put the others in the correct left/right "front" pre-outs. My "rear" pre-outs are empty, and I assume this an ok way to run stuff based on how the amp is wired to the speakers.

The single remaining issue is the power antennae. It does not raise. There was an antennae wire labeled on the wiring harness and the adapter harness, and besides that, I don't know what else would affect it. Right now I can only get one local station, and that's it. Kinda sucks. Any input into making the antennae raise when the tuner is selected?

Posted By: raydawg357
Date Posted: November 30, 2011 at 3:01 PM
In your factory wiring harness behind your HU, you should have a BLACK/ red wire.  This is your power antenna wire.  Your radio should have a solid blue wire to connect to it.  If not. you can use your amp turn-on or accy wire to connect to it.  This should cure your antenna problem.

Do it right the first time

Print Page | Close Window