headunit won't turn on, need help

[thaster 10+ year member]

i am trying to install my pioneer premier m680p headunit into my g20 and the headunit won't turn on. I used a DMM and found out that the wire harness read 12 volts but when i connect headunit power wire to the harness, it now reads 5 volts. I then try to connect the harness power wire to the acc wire and it read 9 volts. Anybody know what the problem is?

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[thaster 10+ year member]

anyone?

 

[thaster 10+ year member]

help please

 

[Ali1 10+ year member]

ur post is confusing.... what do you mean by head unit power wire

 

[FenixAudio 10+ year member]

its a nissan, you will need to make your own ground. the head unit is tryingto ground through someting. just make your own ground and you should be good if you have 12v on red and yellow.