Eletrical Volatage Problem

[Red Recluse]

Alright I recently installed a Pioneer AVH6400CD in the car. The car was driving fine until a few weeks ago, it wasn't cranking over and if it was it was idling around 1-200rpms and sounded like a Harley... The turbo timer was also freaking out, so I looked at the volatage and it was bouncing from 9-10.2 volts MAX..

First I pulled the battery, 650 cold crank amps, 13.5 volts....good to go.
Just got a new alternator for it - now when the key was in the ignition it was still around 10.8, then idling around 11.5 volts... I'm thinking it's the head unit.

Suggestions? All terminals are clean, all grounds are secured and everything is good to go so I'm lost. I love DSM's.

 

[saw wave analog]

sounds like the voltage regulator to me, possibly a grounding issue. im not familiar with the charging systems on dsms so im not sure if the volt reg. is integrated into a larger system or if its its own little entity. either way, they are cheap, and if it is integrated you can go buy a standalone from autozone for 10 bucks and run it to see if it fixes it. you can test the voltage regulator by having the car iding and running a wire from the ground input field terminal on the alternator directly to chassis ground, watch the voltmeter, if the voltage shoots up its the regulator. dont leave it like that obviously as it will blow up your battery and alternator, all it takes is a second to find out. the voltage regulator works by varying the amount of ground the field sees, the more ground it gets the more juice the alternator puts out. should be around 13 volts on a properly functioning charging system.

if it started immediately after the head unit install id look for a massive short somewhere in the switched power wire.. if its that bad though you would probably be seeing smoke.. but anything is possible

 

[Red Recluse]

A grounding kit wouldn't effect it would it?

 

[saw wave analog]

no i dont see why it would unless its grounded to something that is seeing power and just shorting it all to ground. the voltage regulator test takes 1 minute, try it before you do anything more complicated.

 

[steve]

Check the easy stuff first like the alternator fuse and update your profile so we don't have to guess what year car you have.

Steve