HU installation and major problem!!!

[techiedork]

Hi all,
This is my first post. I am doing some work on my brother's 2002 G20 and am replacing the head unit with an aftermarket HU. His G20 has the factory installed BOSE system. I removed the factory HU, installed the Metra 70-7551 harness (all connections are correct) and installed the HU. I got power to the HU when pressing clock or CD Eject (and the antenna begins to extend) but then it shuts off and the antenna retracts. Other than that, I cannot get the HU to power up.

I tested the voltage across the 12 volt constant power and ground and got 12 volts on the multimeter.

Then I tested the 12v switched (accessory) and ground and am coming up with nothing (about 5mA).

So, I believe that the issue lies in the lack of accessory power. BUT, I cannot find any blown fuses (I tested resistance across any that had to do with audio system and electronic components and all test perfectly), the accessory relay seems to be fine...everything seems fine. So then I tried plugging the factory HU back in and am getting no power.

SO, something has kicked the bucket somewhere, but I cannot figure out where! Might there be a fuse in the factory amp (in the trunk, I believe) that might have blown and is preventing the HU to power on? Anything else I can check or do to get this thing working again?

Any help would be greatly appreciated...thank you in advance!

-David

[SteveTheTech]

Hi David,

Let's get to business,

This is the Metra 70-7551, is this what you installed?

(1)I tested the voltage across the 12 volt constant power and ground and got 12 volts on the multimeter.

(2)Then I tested the 12v switched (accessory) and ground and am coming up with nothing (about 5mA).

You have two measurements here.
I have numbered them for discription

1- Where was this test performed?
What color wire was it on the new harness?
What was your voltage reading on the vehicle side of the factory harness?

2- Is that a misprint or is it really 5mA?
Why and how did you measure amperes?
What was the voltage on that red wire?


When you measured resistance on the fuses did you remove them?

You measure available voltage on both sides of the fuse and would only measure the resistance value if the component is isolated (removed).

I am a little confused.

[techiedork]

Hey Steve,
Thank you so much for the reply. I will start by saying that I finally figured it out! Yes, I am using the Metra harness shown above, but turns out that when Metra pinned it out, they swapped the red and orange wires...so the reason I was not getting any voltage over the red wire was because that was supposed to be orange (illumination). Turning on the headlights now confirms this as I get 12 volts over the red wire (which should be acc) when the lights are on!!!

I was pulling the fuses to test them and was testing the resistance, which read correctly. Also, testing all runs of wire from fuse to factory harness was checking out perfectly. I was so stumped, and I should have been paying more attention to pin outs vs. just wire color, but I thought I was working with correct colors. Once everything checked out perfectly, I started reading even more carefully.

Thank you so much for the help - this little snafu taught me quite a bit!!!!!!!!!


Thanks,
David

[SteveTheTech]

Nice fix,

That is why they call it aftermarket.

Cheers,