I searched on this and couldn't find anything that really matched my situation. There are two suspects - the battery and the alternator. Here goes...
What happened:
Yesterday I installed a set of Steeda underdrive pulleys on my car. I had the radio on for about an hour and then it just shut off -- battery was definitely dead. After I put the car back together, I jump started the car and checked the voltage - 14.0V. I'd heard that since UDPs don't drive the accessories as fast, voltage at idle could be an issue. I let it idle for about 10 min while I put the tools away.
So I took it out for a test drive and at two different points, the battery light briefly came on and the message center said "CHECK CHARGING SYSTEM", then after a second, it went back to normal. Car didn't experience any symptoms. This was at night and the lights didn't dim at all. I figured it must've been the battery being so dead or something. Both cases happened as engine RPM were dropping from about 2500 RPM -- the first one coasting to a stop sign, and the second going from a 4th to 5th shift.
This morning I decided I should scan for DTCs just to be sure, and I saw P0622 Generator Field "F" Terminal Control Circuit (from Torque App). I cleared the codes and decided to datalog on my way into work this morning, and everything was fine -- until I was backing into the space, again as RPMs dropped from me working the gas/clutch. Scanned it again -- yep. P0622.
My primary suspect's the alternator right now. The weird thing is it was 100% OK until I swapped out the pulleys yesterday. But I didn't do anything to the alternator other than change the lower-driver's side mounting bolt to the one that came w/ the Steeda kit. Just as you'd expect w/ a UDP install, I didn't disconnect or disturb any charging system related wires.
Here's the main reason I suspect the alternator (this morning's datalog):
Red is voltage at the PCM (left scale), blue is engine RPM (right scale)
That 15.43V spike was right around the time I was parking (when the battery light and "CHECK CHARGING SYSTEM" popped up again). I didn't take note of the exact time, so i'm only 90% sure.
Zoomed in:
I datalogged on the way home too, and didn't have any problems (of course). voltage dipped a couple times (that last big dip was when I turned on my headlights and the HIDs were warming up), but there were no spikes.
On the battery side of things, I know the battery's been on its way out for a while -- ever since last winter when it got pretty cold -- if I didn't drive the car for about a week, it'd be flat. Leave my cell charger plugged in for 3 days and it'd be a little slow to turn over. After the test drive and everything, I checked the battery and it was ~11.9V I left it on a battery tender overnight and this morning it was ... ~11.9V. I drove it into work and when I shut the car off -- again about 11.8 - 12.0V. It's a 4 year old Optima Red top.
What happened:
Yesterday I installed a set of Steeda underdrive pulleys on my car. I had the radio on for about an hour and then it just shut off -- battery was definitely dead. After I put the car back together, I jump started the car and checked the voltage - 14.0V. I'd heard that since UDPs don't drive the accessories as fast, voltage at idle could be an issue. I let it idle for about 10 min while I put the tools away.
So I took it out for a test drive and at two different points, the battery light briefly came on and the message center said "CHECK CHARGING SYSTEM", then after a second, it went back to normal. Car didn't experience any symptoms. This was at night and the lights didn't dim at all. I figured it must've been the battery being so dead or something. Both cases happened as engine RPM were dropping from about 2500 RPM -- the first one coasting to a stop sign, and the second going from a 4th to 5th shift.
This morning I decided I should scan for DTCs just to be sure, and I saw P0622 Generator Field "F" Terminal Control Circuit (from Torque App). I cleared the codes and decided to datalog on my way into work this morning, and everything was fine -- until I was backing into the space, again as RPMs dropped from me working the gas/clutch. Scanned it again -- yep. P0622.
My primary suspect's the alternator right now. The weird thing is it was 100% OK until I swapped out the pulleys yesterday. But I didn't do anything to the alternator other than change the lower-driver's side mounting bolt to the one that came w/ the Steeda kit. Just as you'd expect w/ a UDP install, I didn't disconnect or disturb any charging system related wires.
Here's the main reason I suspect the alternator (this morning's datalog):
Red is voltage at the PCM (left scale), blue is engine RPM (right scale)
That 15.43V spike was right around the time I was parking (when the battery light and "CHECK CHARGING SYSTEM" popped up again). I didn't take note of the exact time, so i'm only 90% sure.
Zoomed in:
I datalogged on the way home too, and didn't have any problems (of course). voltage dipped a couple times (that last big dip was when I turned on my headlights and the HIDs were warming up), but there were no spikes.
On the battery side of things, I know the battery's been on its way out for a while -- ever since last winter when it got pretty cold -- if I didn't drive the car for about a week, it'd be flat. Leave my cell charger plugged in for 3 days and it'd be a little slow to turn over. After the test drive and everything, I checked the battery and it was ~11.9V I left it on a battery tender overnight and this morning it was ... ~11.9V. I drove it into work and when I shut the car off -- again about 11.8 - 12.0V. It's a 4 year old Optima Red top.
