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Help- radio install issue

R

rsm688

Well-Known Member
Messages
234
Location
mississippi
Okay guys I'm trying to get my new nav system in and am having some issues. I'm using a GMOS-04 adapter. Everything works good except I have no sound from the rear speakers or sub. I can hear a faint buzz from passenger rear speaker when I put my ear to it but no sound is playing from anything except the front door speakers and tweeters.

Anyone have an idea or what might be going on?

Thanks,
Spencer
 
S

SedonaBound

Guest
That harness uses the head unit only as a preamp to feed a separate amplifier. If you don't have an OEM "Monsoon" system or another amp, the speakers have to be wired directly to the head unit. If it is a Monsoon system, there's a procedure in the Metra instructions for setting the audio level it sends to the amp. If you don't have a amp in the system, the speakers have to be connected directly to the head unit and not through the harness.

If that doesn't answer it, look for previous DIY mods in the wiring to the factory harness and head unit.
 
R

rsm688

Well-Known Member
Messages
234
Location
mississippi
Thanks Sedona, I have the monsoon system. I saw that about setting volume but I thought that was overall volume. I have good volume from front speakers but nothing from the rear.

Thanks,
Spencer
 
S

SedonaBound

Guest
rsm688 said:
Thanks Sedona, I have the monsoon system. I saw that about setting volume but I thought that was overall volume. I have good volume from front speakers but nothing from the rear.

Thanks,
Spencer
Click to expand...
I'd start by following the sequence for "Testing the GMOS-04" to set the chime volume, turn the RAP power fully off by removing the key and opening the door, then follow the steps for setting audio level. Since your problem is affecting three separate speaker circuits (LR, RR, sub) its unlikely to be a simple loose wire or plug pin problem. If that doesn't do it, you'll have to use a voltmeter to trace the head unit's signal to each speaker to find the problem.
 
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
Sounds like the amp power is off. It will be the Blue/White wire on the GMOS04 unit. If you used the the power antenna lead from the head unit, there may be setting to on the radio to change it to power.
 
S

SedonaBound

Guest
Some amps have relays that protect speaker coils from being fried by voltage that's too low. Do the Metra "test" procedures for the harness module to set chime and audio levels. It can't hurt, and it may be the problem; module may not be passing enough voltage to the amp to run rear spkr amp circuits. Make sure the OEM unit is off, the key is off, and open the door before taking it out again.
 
Last edited by a moderator:
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
Okay, lets review the wires . . .

After looking through both diagrams (DNX690HD and GMOS04), looks like most of the wires line right up!

Code: 
GMOS04          Kenwood         DESC            
------------------------------------------
Red             Red             Ignition +12v
Orange/White    Orange/white    Lights  
White           White           FL+
White/Black     White/Black     FL-     
Gray            Gray            FR+
Gray/Black      Gray/Black      FR-     
Green           Green           LR+
Green/Black     Green/Black     LR-     
Purple          Purple          RR+
Purple/Black    Purple/Black    RR-     
Blue/White      Blue/White      Amp Turn On 
Brown           Brown           Mute    
Light Green     Light Green     Parking Brake
Blue/Pink       N/A             VSS
Green/Purplek   Purple/White    Reverse 
Black           Black           Ground
Yellow          Yellow          +12V

After looking at my old setup where I used the GMOS04, I used the low level outputs, not the speaker outputs. Here are the pics from my install back in 2008: :link:

Maybe the high level audio was too much for the GMOS04 and you blew out the pre-amp in it. Do all the speakers work with the original radio?
 
Renagade132

Renagade132

ZAMU
Messages
1,248
Location
New Jersey
How about the possibility of a bent or loose pin in the new harness, or where it connects to, or maybe even worse, the new harness is a bad?
 
R

rsm688

Well-Known Member
Messages
234
Location
mississippi
Cbetts, by low level outputs do you mean that you used RCA cables on it?

I talked to a certified Kenwood tech that repairs all the headunits and all (my aunt owns a major electronic repair company, they unfortunately don't do wiring stuff) and he said he thinks maybe the amp is not working because the signal is too high from the headunit and that the reason the front speakers and tweeters are working is that they don't require as much power and the factory head unit has a small amp that sends some power to them.

I got another GMOS-04 and tried it and no luck as well. My antenna is not connected because I forgot to get an adapter but I highly doubt that would have any effect on it.

Could I use RCA cables and splice them into the harness since it would be a lower level output? It looks like that is what you did on your install. Did you just buy some RCA cables and cut and splice them or what?

I'm stumped here. I wish I could call Crutchfield for tech support but since I did not buy a radio or wiring harness adapter from them they won't give customer support. Anyone buy a metra/axess wiring adapter from them and want to let me borrow your invoice/order number lol?


Thanks,
Spencer

cbetts said:
Okay, lets review the wires . . .

After looking through both diagrams (DNX690HD and GMOS04), looks like most of the wires line right up!

Code: 
GMOS04          Kenwood         DESC            
------------------------------------------
Red             Red             Ignition +12v
Orange/White    Orange/white    Lights  
White           White           FL+
White/Black     White/Black     FL-     
Gray            Gray            FR+
Gray/Black      Gray/Black      FR-     
Green           Green           LR+
Green/Black     Green/Black     LR-     
Purple          Purple          RR+
Purple/Black    Purple/Black    RR-     
Blue/White      Blue/White      Amp Turn On 
Brown           Brown           Mute    
Light Green     Light Green     Parking Brake
Blue/Pink       N/A             VSS
Green/Purplek   Purple/White    Reverse 
Black           Black           Ground
Yellow          Yellow          +12V

After looking at my old setup where I used the GMOS04, I used the low level outputs, not the speaker outputs. Here are the pics from my install back in 2008: :link:

Maybe the high level audio was too much for the GMOS04 and you blew out the pre-amp in it. Do all the speakers work with the original radio?
Click to expand...
 
Last edited:
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
rsm688 said:
Cbetts, by low level outputs do you mean that you used RCA cables on it?

I talked to a certified Kenwood tech that repairs all the headunits and all (my aunt owns a major electronic repair company, they unfortunately don't do wiring stuff) and he said he thinks maybe the amp is not working because the signal is too high from the headunit and that the reason the front speakers and tweeters are working is that they don't require as much power and the factory head unit has a small amp that sends some power to them.

I got another GMOS-04 and tried it and no luck as well. My antenna is not connected because I forgot to get an adapter but I highly doubt that would have any effect on it.

Could I use RCA cables and splice them into the harness since it would be a lower level output? It looks like that is what you did on your install. Did you just buy some RCA cables and cut and splice them or what?

I'm stumped here. I wish I could call Crutchfield for tech support but since I did not buy a radio or wiring harness adapter from them they won't give customer support. Anyone buy a metra/axess wiring adapter from them and want to let me borrow your invoice/order number lol?


Thanks,
Spencer
Click to expand...
Correct, I used the RCA connections. Looking at the picture, it looks like the GMOS-04 has RCA inputs. Just use a patch to connect the pre-amp outputs on the head unti to the RCA inputs on the GMOS-04.
 
R

rsm688

Well-Known Member
Messages
234
Location
mississippi
Last edited:
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
That is weird. Mine definitely came with RCA inputs.
h120GMOS04-f.jpeg


I also moved away from it to the PAC-Audio OS-2C-BOSE because I kept getting alternator noise through the Metra model. I think I still have my model sitting around. Shoot me a PM and I can send it to you to see if it helps.

Did you try putting the stock head unit back in to verify there is nothing wrong with the factory side?
 
R

rsm688

Well-Known Member
Messages
234
Location
mississippi
I sure did, everything works perfect with the factory radio (it's back in right now). I got some RCA terminals, going to solder them on. If that doesn't work I very well may take you up on that generous offer and see if it will work with your harness. I'm stumped on this one, I've installed numerous stereos with zero issues before

thanks again,
spencer

cbetts said:
That is weird. Mine definitely came with RCA inputs.
h120GMOS04-f.jpeg


I also moved away from it to the PAC-Audio OS-2C-BOSE because I kept getting alternator noise through the Metra model. I think I still have my model sitting around. Shoot me a PM and I can send it to you to see if it helps.

Did you try putting the stock head unit back in to verify there is nothing wrong with the factory side?
Click to expand...
 
R

rsm688

Well-Known Member
Messages
234
Location
mississippi
rsm688 said:
I sure did, everything works perfect with the factory radio (it's back in right now). I got some RCA terminals, going to solder them on. If that doesn't work I very well may take you up on that generous offer and see if it will work with your harness. I'm stumped on this one, I've installed numerous stereos with zero issues before

thanks again,
spencer
Click to expand...


IT WORKS!!!!!!!!!!!!!!


I soldered all the speaker output wires from the harness to some RCA plugs and used them instead and it works perfect. Did a little digging and spoke with the Kenwood tech that works for my aunt and apparently the factory amp cannot read the high output signal from the head unit since it has a pre amp built in so you must have to use the low output RCA signal for the factory amp to be able to use the signal.
 
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