07 Liberty Stereo (RBK v2) Upgrade

Discussion in 'Electronics' started by tinyhousevt, Dec 2, 2020.

  1. tinyhousevt

    tinyhousevt New Member

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    My '07 has the second version of the RBK (see this page), the version without the cassette player and Balance/Fade dials. On the build sheet this is listed as AM/FM Compact Disc Radio w/Chgr Ctr although I don't have a disc changer. I also don't have the infinity speaker package, so there shouldn't be additional amplification required.
    I bought a single DIN head unit, the BOSS 616UAB, which is rated for 50Wx4, and the necessary cable adapter from Scosche. The new head unit power on and seems to function normally, but the speakers won't play any output. The head unit is putting out ~110 ohms to each speaker. I don't have an easy way to compare this to the output from the RBK without manually wiring it to a battery. Am I missing something? I've seen others put in 40W units without issues, is mine just bad?
     
  2. DadOSix

    DadOSix Full Access Member

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    Not too familiar with the radio setup.

    thoughts:

    i reread your post and noticed no separate amp, so i edited that out.



    you are likely not measuring ohms for output power. Ohms is a resistance/impedance measurement with no power applied to that part of the circuit. So not sure what you would be measuring. I blew up an analog meter that way, even after my prof. Told us not to try it.

    does the new head support the speakers you have? Ie 4ohm vs 8 ohm.

    did you hard wire the head or use a commercial harness? Like metro or crutchfield

    i see looking at your like that the radio has a fuse on back. Assuming you checked that it is good.

    that top connector shows just speakers. If you did not use a prepared harness, is the wiring running to your speakers correct. Ie green, green/white;brn,brn/white etc.

    is there a selection in the radio setup to use standard outputs vs pre-amp.

    post up a bit more. Maybe we can sort your radio.
     
    Last edited: Dec 2, 2020
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  3. tinyhousevt

    tinyhousevt New Member

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    My electrical knowledge fails me more often than not. [​IMG]

    I stuck my multimeter on the RR+/-, LF+/- etc terminals to make sure the head was actually outputting something. Should I be measuring for voltage here?
    The label on this unit says 4~8 Ω and the manual says 4 Ω. The 6 stock speakers in the car are 4 Ω I believe? I am not very familiar with the implications of these numbers.

    I have a commercial harness wired to the stereo's harness. I have checked and double checked continuity and that all the wires are connected to the right color.
    The stock RBK stereo is currently in the car and works just fine. The fuse in my new head unit is also good.
    There is an option on the new head unit called 'Loud'. I think this might be a speaker level adjustment, the manual doesn't specify. Either way, toggling it does nothing.
     
  4. DadOSix

    DadOSix Full Access Member

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    Great so far!

    you have proved that the speakers and wiring to them is correct.

    your meter would need to be set to volts to the lowest level to see any output from the new head. So I was going to suggest checking the ohm scale across each speaker pair. No need, as you proved above.

    2 things jump out at me.

    1 - software in the head may need to be set up. Again, not familiar with this unit, but some allow you to switch output between the ‘preamp’ vs speaker leads. Those preamp terminals would allow you to add an aftermarket amp.

    2 - most likely, as i’ve been burned here before, is the interface harness.

    i assume the radio powers up.

    So - on the harness, double check and be sure all the pins are fully inserted in the connector. I have a big chevy van that had an intermittent speaker problem, and after 5 tries, i finally thought of the harness connector. One end was perfect, the other end, at the factory harness end, had 2 pins not fully seated. If they are loose, a little flat screwdriver, or a finishing nail is sufficient to push em back into place.

    keep up good detective work!
     
  5. DadOSix

    DadOSix Full Access Member

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    Check put this guy putting a new unit in a liberty.

    are all 4 wires on the lower plug connected?
     
  6. tinyhousevt

    tinyhousevt New Member

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    RADIOArtboard 1@2x.png
    Here's where we stand:
    I found what appears to be the right pinout diagram for my radio, so I've double-checked that everything is plugged into everything.
    I've found a few people online who fixed this issue by giving the amplifier (blue) cable power. There doesn't appear to be an amplifier in this car, as there's no cable running out of pin 21.
    In the diagram above, under OEM Vehicle Harness are listed all of the pins actually used in my Jeep. There's no pinout for an amplifier, although my aftermarket harness has space for one.
    The only wires currently unconnected from the radio are Pins 13 & 24 - PWD (Power Dimmer) and J1850, which I believe to be the onboard diagnostic module. The dimmer just sends pulses to change brightness, having it disconnected shouldn't do anything. I don't think having the radio not speak to the ODM would cause issues, either.
    Is it possible the housing of the radio needs to be grounded as well, just to something metal inside the dash cavity?
     
  7. DadOSix

    DadOSix Full Access Member

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    Love yr diagram!

    Does yr new head even power up?

    if so, i’d be inclined to try +12v switched (red) to that ant+ (pin 3 ) if i read yr diagram correctly. Just a SWAG, but i wonder if the head is waiting to see +12 there before it outputs sound.
    You’ve proven everything else to work.

    i’m not certain, but just maybe.
     
  8. profdlp

    profdlp On The Ledge

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    Did you buy an adapter to go between the head unit and the wiring harness in the Jeep? If not, assuming you haven't already cut wires, that is the way to go.
     
  9. tinyhousevt

    tinyhousevt New Member

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    @DadOSix The head does everything but make sound when you plug it in. I tried wiring the ANT+ into the red wire at first. It doesn't give a current while the radio is running, just on power on/off. It's only on my harness, and I believe it's for raising and lowering a power antenna.
    @profdlp The middle column of my above diagram is an adapter, it matches the OEM plug and has standardized color wires coming out of the pins. I've wired these to the ISO harness that came with the radio, the right column above.

    I'd rather not take my door apart to check, but it seems that the 6 stock speakers are 4Ω from what I'm reading online- which should work with my head unit. From my loose understanding of how this works, if they were 6Ω speakers instead that would be too much load for my 4Ω rated stereo unit?
     
  10. profdlp

    profdlp On The Ledge

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    I used to sell stereos about 40 years ago and could have given you a better answer back then, but my understanding of matching impedance is that it is really just a matter of efficiency. Car users like 4 Ohm speakers because they will be louder for a given power input than 8 Ohm speakers, such as you might use on a home stereo. (Remember when those were a big deal?...) Anyway, my point is that you ought to be getting SOMETHING.

    Do you have an old speaker laying around you can hook up to one channel for testing purposes? That might get you headed in the right direction. I'd bypass the speaker connection in the harness and hook it straight to the head unit.

    And sorry if I missed it, but has this been addressed? --> 1 - software in the head may need to be set up. Again, not familiar with this unit, but some allow you to switch output between the ‘preamp’ vs speaker leads. Those preamp terminals would allow you to add an aftermarket amp.
     
  11. tinyhousevt

    tinyhousevt New Member

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    I've got 4 extra 6Ω speakers and a pair of 8Ω. I can try direct wiring those.
    Hey, I still think home stereo is a big deal! I'm very proud of my 7.2 surround made of a hodge-podge of Goodwill speakers.

    As for the software issue, there's nothing I can do on the unit to 'switch' between the low-level outputs and the RCA outputs for the pre-amp. I'm assuming they both output simultaneously since you use one or the other? I have an RCA cable and something I can use an amplifier to see if those outputs are working.
     
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  12. DadOSix

    DadOSix Full Access Member

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    Hmm.
    I got nothing else off the cuff.

    unless you try a speaker (for a few seconds) directly to one of the speaker outputs and bypassing the matching harness.

    like i said, just a few seconds, because you have no loads on the remaining 3 outputs.

    i still want to think it is the adapter harness.
     
  13. DadOSix

    DadOSix Full Access Member

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    Ever get this working?
     
  14. tinyhousevt

    tinyhousevt New Member

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    Finals for school caught up to me and I've just stuck the original stereo back in it. I've picked up a MIL again so that will take priority.... Just Empty Every Pocket!
     
  15. DadOSix

    DadOSix Full Access Member

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    Ain't it the truth!