2007 Doublcab Head Unit replacement

I did a lot of reading before I went out to by my aftermarket head unit. I got a unit with a 4 volt preamp out because I read somewhere that worked best. I hooked up my new unit using a

$70 TYTO-01 JBL Amplifier Interface Harness, BLACK

TYTO-01. It didn't seem right because I didn't utilize the after market head units sub out RCA jack. I only used my front and rear RCA outs from my aftermarket head unit. Problem is I can't adjust the subwoofer gain on my aftermarket HU because there is nothing hooked up to it from the TYTO-01 kit. Is there a way around this so I can utilize this feature in the aftermarket unit. I can here tye subwoofer but it doesn't sound as good unless I am able to adjust the level independently with the HU like normal systems. Am I doing something wrong?

 

Check the male pins in the Metra harness where it plugs into the Toyota harness. Make sure all the pins are properly aligned. Occasionally the pins on the Metra will be too short and won't actually make contact with the Toyota harness. You have the JBL speaker system, correct?

 

Yes I do. the system works the problem is that on my Sony HU only the front and rear RCA outputs are used with the TYTO harness. The one labeled front RCA ouput controls the mids on the front doors and tweeters. The one that says rear RCA outputs control the mids on the back doors and the subwoofer. I was thinking the subwoofer would have its own seperate RCA input which is the sub output on the Sony HU, that way you can control the sub independently. You know how HU nowadays can control the sub level independly? Well with it wired this way it can't. I was wondering if there was a work around.

 

I've never used a stock JBL head unit, so I had to do a little researching of my own. The Metra

$70 TYTO-01 JBL Amplifier Interface Harness, BLACK

TYTO-01 isn't supposed to use your Sony's sub pre-out because of the way the JBL system is wired. In the JBL system, the amp/sub pulls its signal from the rear speakers. The JBL amp takes that signal and filters out everything except bass and then passes the filtered signal to the sub. So there are no wires going directly from the stock head unit to the amp or sub. Hence, no wires going directly from your Sony to the amp or sub.

The only way I can think to adjust the sub's volume independently is with an aftermarket amp and sub (which will require running new wiring). I'm not an installer or anything, but that's the only way I can think of, that would allow you to control the sub independently. If someone else on TacomaWorld knows of another way, I hope they chime in. Or if I'm completely wrong, I hope they chime in about that too.

 

Take a look at page two of this diagram. You have four wires coming from th sub to the amp. Then you have 4 more wires coming from your amp to you HU. (red, green, black, white) and the shield. Without knowing the theory of operation I could just assume that those wires going to the amp from HU are for the sub. So is it possible just to bypass the TYTO harness for the sub only and convert those wires to RCA jacks to use the sub out on the Sony HU? If so that would be awesome, but if there was a way I would think that the company that makes the TYTO harnesses would have incorporated this to their adapter. That would only make sense.

 

Looking at that diagram, I would come to the same conclusion you did. And I would think, like you did, that the company that makes the TYTO harness would have thought of incorporating the sub functions into the harness. Since you can get some sound from the sub, it seems like everything is incorporated into the harness and is working correctly. It seems that the JBL system was not designed for independent sub control. And even with an adapter, it still seems like its not possible. (these are just my thoughts, not facts)

The previous aftermarket decks I've owned will only allow independent sub woofer control if a cable is plugged into the sub woofer pre-out. I think if this is what you want to achieve, you'll have to bypass the JBL amp. But only bypass the sub wiring because it looks like, according to that diagram, the door speakers are powered off of the stock JBL amp as well. If you did bypass the amp, then you'll have to put in an aftermarket amp and sub woofer. From what I've read, you can't run the stock JBL sub with an aftermarket amp.

Sorry I don't have any definitive answers for you. I'm just trying to help since no one else was. Maybe if you change this thread's title to something about independent sub woofer volume control you'll get more traffic and maybe some help from someone that knows more about the JBL system than I do (which is not a lot). In similar threads about the JBL systems, the guys that seem to know their stuff the best always recommend ditching the JBL system altogether.

 

Well thanks for the help I would change the Thread title but unsure how to unless I start a whole new thread and explain everything again. What I think I'm gonna do is try to bypass the TYTO harness for the SUBS ONLY and convert to RCA jacks and hook up to the HU Sub Out. It looks like per the drawing the that the mids and tweeters are digitally controlled with the TX- and TX+ wiring. If it works I'll post to let others know because there's plenty of info on the TYTO harness but no info that I've found on if you can indepently control the sub or someone who has tried with no success.

 

That sounds like a good plan and is what I would try. Good luck with it and be sure to post on this tread how it all turned out. Pictures are always helpful too!