My radio on my 04’ conked out. Got a replacement HK amplifier. Didn’t work. Took it too a professional, they tested one of the power pins at the amp and it gave 12vs however, the other one that either powers rhe amp or goes to the head unit was pulling 1ish volts. There is very little information pertaining to this radio issue in terms of a solution.

It crackled, popped, and did work again until the audio professional did an add a circuit and pulled a stand alone wire to the amp.

All I have ever been able to find online is a mystery relay that apprently is yellow and located behind the glove box.

Pulled the glove box and much like others who have described this issue they didnt find a yellow relay.

The mysterious poster with a solution to this problem also never posted a part number.

Photographs provided contain Connector C0153 and C0901. Densos. The rubber boot around the relay outlines a different part number then what actually houses and connected within. After looking it up I identified it is for the automatic temperature control ie blower motors and relative speed.

 

Do you have a copy of the Electrical Troubleshooting Manual and the Electrical Library? They are essential for problems like this. Do you have highline audio with a subwoofer in the back door? Nav? Rear audio? Here's the diagram of the basic power supply circuit. The rest of the pages are in the ETM if you need to get deeper..

 

Oh I have the diagrams. I lack the focus to retain information after a couple glances so this is not my first rodeo with this. A lot of people in the past have identified that this phantom relay is not there when they pull the glove box.

Honestly, if you could help me identify my stereo that would be super helpful for verification purposes as it confuses me.

If by subwoofer in the back door you mean that 6” speaker then yes I have that. No nav I believe. And I have the rear audio connections. My amp is under the front driver seat and I believe it is HK and the cd player is under the front passenger.

The thing that tripped me up recently about the drawings are the there appears to be colors related to the entertainment system in one of those relays.


C901-1 GW
C901-2 UR
C901-3 BO
C901-4 B

C153-1 LGW
C153-2 N
C153-3 NR
C153-4 WR
C153-5 B

EDIT: This is a similar post outlining similar issues.

That seems to be the exact situation the audio fella told me. I am a little frustrated because I paid a couple hours worth of labor for an add a circuit. My radio works currently but the rats nest of gauge wires and add a circuits makes it look like the switch board operator in the movie Down Periscope. I certainly and starting to feel like I am that guy.

 

Those relays (C0153, C0901) have nothing to do with the head unit or the power amp. To my knowledge there is no relay powering the amp. Head unit and power amp have permanent battery power (since it possible to use the stereo without ignition key in the barrel). If the head unit is turned on, it sends a 12V control signal to the power amp which activates it.

When you turn on the head unit you should measure 12V on C0098 Pin 5 "system enable". This is the control signal to activate the amp.


https://pinoutguide.com/Car-Stereo-O...2_pinout.shtml


Source: https://pinoutguide.com/Car-Stereo-O...2_pinout.shtml

 

Okay. I am starting deep in my teeth in this now. I got my amplifier exposed as I am doing some clean up. So, currently there is an add a fuse power line that was spliced into the LGP line into amplifier electric plug. I did not verify the pin number but I am certain this was done because of the low voltage kicking out, thus bypassing the issue and powering the amp. Previously there was power but no sound.