Battery voltage problem on an MY04?
 

I've transferred an SPA gauge over to my MY04 WRX and am getting the low volts alarm (i've set at 12v) virtually all the time at idle and flickering in slow traffic.
It came off an MY97 which never did this - is it an indication of the dreaded dead battery problem that affects STis - I do have a tracker fitted as well.

Nick

could be because the alternator only charges when it needs to so is constantly cutting in and out. i think it has to drop to just below 12v for the ecu to sense it and bring the alternator in.

Where have you picked up the 12V signal from? I wouldn't think the battery volts are really this low, it would struggle to start the engine if they were. Sounds to me like you don't have a good connection to 12V or you've picked up some kind of voltage regulated (to less than the normal 12V) supply.

Stick a meter direct across the battery if you're not sure, should read 12.8V or so with the engine not running and more like 14V with the engine running, even at tickover.

I've linked into the 12v feeding the fag lighter.
Like I said, its only at low rpm that the light shows up - the idle is a bit stuttery now I come to think of it.
I'll find my voltmeter and check.

Nick