HU harness problem

Troender

Member
I tried to replace my old Pioneer FM head unit with a new DAB+ unit from Grundig today.

The wiring and The existing harness looked funky, But worked initially. But then There where a frightning puff of smoke from The stearing colomn. I discovered that one of The pins of The harness was hanging loose. (The one connected to The DIY looking yellow cable, patched in to The red wire.

No fuses was blown, But There is no power to The head unit any more. Problably because that The pin now is in The wrong place. Please take a look at The pictures.

Everything else works like it should.

What to do?
 

Attachments

  • FB1FF433-8F12-4F1E-A48A-D0ACB164E343.jpeg
    FB1FF433-8F12-4F1E-A48A-D0ACB164E343.jpeg
    1.3 MB · Views: 96
  • 5F3CCB39-A0E4-4730-9999-B393CF8E711F.jpeg
    5F3CCB39-A0E4-4730-9999-B393CF8E711F.jpeg
    1.4 MB · Views: 90
  • 14702393-A2EE-444C-A3D2-89782D323C3F.jpeg
    14702393-A2EE-444C-A3D2-89782D323C3F.jpeg
    1.3 MB · Views: 98
  • C03ABC28-299B-47B5-BB38-722673691F76.jpeg
    C03ABC28-299B-47B5-BB38-722673691F76.jpeg
    1.4 MB · Views: 98
  • E510FC60-1B45-4115-80D6-CA00A59CBD73.jpeg
    E510FC60-1B45-4115-80D6-CA00A59CBD73.jpeg
    1.3 MB · Views: 97
Hi, what year is the car?
Also, did the Pioneer switch with the ignition, so the radio only works when the engine was on, or did it work regardless of the ignition, as long as the key was in the ignition, even when the ignition itself was off?
Mac.
 
Last edited:
Yes. It is a 2002. The pioneer radio worked as long as the key was in the ignition. I guess that is the work of the yellow cable.

My theory is that the yellow cable was too low gauge for the new radio, and made it hot. Thus the smoke.

I have to open opp the stearing colomn to find the other end of it. I guess it comes from there? What bits do i need to unscrew the plastc cover?
(It is still strange that no fuses was triggered by the smoke insident.)
 
Last edited:
It is usual for the radio to be permanently connected to 12 volts for power, but also have a switched 12 volt input, that tells the radio to run (12v), or go into standby (0v). For the radio to work as long as the key is in, that switched 12 volts has to come from the "S" contact. This is a switched 12 volts from the ignition switch. It is low power fused. This wire runs from the ignition switch, to the "S" contact fuse, then it goes off to do it's job. Could be that this "S" contact has been taken from the ignition switch, before the fuse. The supply to the ignition switch is fused, but at a much higher current 30 amps I think, as there are several different functions controlled by the ignition switch.
Mac
 
I havent used a multimeter on the radio DIN contact, but i`m pretty sure that the power is gone.
It may be the ignition fuse that you mention.

It is fuse 36, right?
 
I think the 12 volt permanent supply to the radio in the original loom is Red/White, from Fuse 2. This should go to the radio wire "Battery"
I'm guessing that the yellow wire is the the switched "S" contact, but I can't find any reference to "S" in the Audi schematic. The radio power must not come from this "S" as it's a low power circuit. If it did, that might explain the smoke ...
Mac.
 
The best I can find is Fuse 44, described as:

Ignition Key Withdrawal Lock Control Unit 10A
Ignition Key Withdrawal Lock Solenoid Valve
Electronic Manual Gearbox Control Unit
Handbrake Warning Lamp Control Unit

Thinking Ignition Key Withdrawal means controlled by key Withdrawal. If I'm right, it's a Red/Blue wire

Best I can do at the moment.
Mac.
 
It will be interesting to open the stearing colomn and take a look. I just have to find out what kind of screws it is. They are seated deep in there.

I will have a look at the low ampage fuses too. But the handbrake warning lamp works. Everything Else does too, so i don`t think that the smoke was a real bad omen. But it made me buy a small fire extinguisher, to place in the Trunck. 😂
Does anyone see if the red wire pin, spliced to the yellow wire is in the right spot in the contact? My guess is that its not.
 
It will be interesting to open the stearing colomn and take a look. I just have to find out what kind of screws it is. They are seated deep in there.

I will have a look at the low ampage fuses too. But the handbrake warning lamp works. Everything Else does too, so i don`t think that the smoke was a real bad omen. But it made me buy a small fire extinguisher, to place in the Trunck. 😂
Does anyone see if the red wire pin, spliced to the yellow wire is in the right spot in the contact? My guess is that its not.
This will help with the steering column cover:
Mac.
 
Here's a pic of the original Audi radio connectors. The power positive and negative on the 8 way plug should be connected to the power positive (battery) on the supply to the new radio. Check that first, and with the yellow disconnected, check with a meter, how the voltage behaves as the ignition switch is turned.
Mac.
 
Last edited:
Here's a pic of the original Audi radio connectors. The power positive and negative on the 8 way plug should be connected to the power positive (battery) on the supply to the new radio. Check that first, and with the yellow disconnected, check with a meter, how the voltage behaves as the ignition switch is turned.
Mac.
You forgot The picture.
 
Back
Top