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1995-2002 Range Rover P38A
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Discussion Starter · #1 ·
Hello everyone,

First of all I wanted to thank the community, for 5 years I've found here the answer to the weirdest questions and this is the first time I have to ask something. You are great!

Recently my Alpine radio died and I decided to Install a Pioneer DMH-C5500NEX unit. I took some pictures of the process and I may post them in case someone find it helpful.

The issue I'm having is that during the startup of the radio I hear noise thought the speakers, when the boot-up finishes the noise stops and everything works fine.

If I disconnect every audio and power cable, I hear the same noise and it stays forever. So the explanation I found is that the amplifiers are on whenever the switch is in positions I or II, and when there is no audio signal they produce this noise.

The thing is that the amplifiers shouldn't be always on, if there is no "remote" signal coming form the radio, they should remain off.

According to the information I've found, the "remote" is the blue wire in connector C0098 (the grey one). But when I measured voltage, I found that as long as the switch is in position I or II, these blue wire has 12V on it. It explains why the amplifiers are on when they shouldn't.

Other information I found indicates that the "Radio cassete remote on/off" comes from the BECM (connector C1285, pin 6, orange cable). But then I cut this wire and it turned out to be the Remote for the Alarm R.F. Antenna Module (as also described in the Electrical Troubleshooting Manual)

I am the third owner of this P38 and I am thinking maybe someone modified the wiring. I could always install new wires to the amplifiers but I would prefer using the existing ones.

For those who have replaced the radio: have you had the same problem?

Thanks in advance,
 

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Remote turn on is on a Grey/Black wire on pin 5 of C0098 from the head unit which will only be powered when the radio is switched on. C0098 does not have a blue wire, it has Grey/Orange (Steering wheel switches), Purple (Permanent live), Grey/Black (remote turn on), Red/White (Illumination), White/Pink (Ignition switched live) and Black (ground). With an aftermarket head unit connect the Grey/Black to the electric aerial feed (usually Blue/Yellow)
 

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1995-2002 Range Rover P38A
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Discussion Starter · #3 ·
Hi Richard, thanks for your reply. I see that pin 5 is supposed to be Grey/Black but in my Rangie it is Blue/Black. Please see the pictures. It doesn't look like a modification, what do you think? Rectangle Slope Font Line Schematic
Electrical wiring Ice cream Ingredient Computer hardware Circuit component
 

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The back of that head unit doesn't look like the pictures of DMH-C5500NEX ???? Most head units can switch the HK amps using their Antenna wire, but this wont account for the audio condition during boot up from the head unit.

Also as I have said many times on this & other forums, the audio feeds to Pins 9 & 10 on each amplifier are Balanced Audio. Simply connecting the RCA line out or Speakers (regardless of attenuators) is gonna create issues. Balancing them properly might help ??
 

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Odd, you've got a full set of wires in C0098 but according to the ETM, only 6 or the 8 ways should have anything in them. Other colours look correct except for the Blue (although it looks like it may be Blue with a Black trace) being the wrong colour and the additional Brown and Grey/Pink which shouldn't be there.

See here, pins 1 and 3 shouldn't have any wires in them.

292843
 

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1995-2002 Range Rover P38A
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Discussion Starter · #6 ·
Hi PWood,

The back of that head unit doesn't look like the pictures of DMH-C5500NEX ????
This is the original Alpine radio, I posted this picture to show the wires I have in the connector

the audio feeds to Pins 9 & 10 on each amplifier are Balanced Audio.
Regardless of being balanced or unbalanced, if I leave all connectors disconnected, no Alpine, no Pioneer whatsoever, only the connectors hanging from the fascia. When the key is in position I or II there is a strong noise coming from the speaker, which means the amps are on. They shouldn't be on because there is no Remote On signal.

Most head units can switch the HK amps using their Antenna wire, but this wont account for the audio condition during boot up from the head unit.
The Pioneer receiver sends 0V during startup through the remote wire, and 12V after boot up, the problem is that the wire in the car is always live. I think I'm gonna need to rewire the whole thing =(

Thanks,

Javier
 

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See what colour the remote wire is at one of the door or antenna amps. It should be the Grey/Black but if it is Blue or Blue/Black it may just be that they'd run out of the correct colour wire and used what they had laying around. Or there is another reason for it.
 

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1995-2002 Range Rover P38A
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Discussion Starter · #8 ·
See what colour the remote wire is at one of the door or antenna amps.
In the door amp it is Gray/Black in Pin 8 as you can (barely) see in the picture. It probably changes change colors in one of the splices

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Check continuity between the Grey/Black at the amp and the Blue/Black at the head unit to confirm it is the same bit of wire. If the Blue/Black has power on it whenever the ignition is on, check to see if that is on the wire or from the head unit.
 

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1995-2002 Range Rover P38A
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Discussion Starter · #10 ·
Check continuity between the Grey/Black at the amp and the Blue/Black at the head unit to confirm it is the same bit of wire. If the Blue/Black has power on it whenever the ignition is on, check to see if that is on the wire or from the head unit.
Good idea, I will. Thanks!
 

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1995-2002 Range Rover P38A
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Discussion Starter · #11 ·
So today I finally had the time to remove the door panel and test for continuity, and there is continuity between the Blue/Black wire on Pin 5 of C0098 in the radio and the Grey/Black wire on Pin 8 on the left front door amp.

I still don't know where the 12V are coming from. Anybody has an idea other than disassembling the whole car to check the harness or to rewire the whole thing?

Here a short video where you can see (and hear) my problem: >> Click here to see the video <<

Thanks,

Javier
 

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1995-2002 Range Rover P38A
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So today I finally had the time to remove the door panel and test for continuity, and there is continuity between the Blue/Black wire on Pin 5 of C0098 in the radio and the Grey/Black wire on Pin 8 on the left front door amp.

I still don't know where the 12V are coming from. Anybody has an idea other than disassembling the whole car to check the harness or to rewire the whole thing?

Here a short video where you can see (and hear) my problem: >> Click here to see the video <<

Thanks,

Javier
Do you have factory satnav?
If so, the Nav unit is turning on the amp as it boots up.
Also, digital noise on boot up can be caused by using a shielded cable, and not grounding the shield. Shield should only be connected at one end, btw.....
You could also try audio line level isolation transformers as you could have a ground loop
causing trouble (noise) between the new head and the stock amps.
 
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