Do alternators usually fail 100% and stop charging or is it possible for them to somewhat charge but barely? The "Check charging system" light came on in my 07 TSX and I did some testing and here's what I get.


If I have all accessories off, I measure 11.5-12 volts at the battery. If I turn on headlights, navigation the voltage starts to drop down to 10 volts and the car will shut off if I continue but when I turn off the accessories, it climbs back up to 12 v while the car is running. It does seem to charge up somewhat because after the battery dies and car no longer cranks, if I jump it and have it run for a while, it will start up again. I don't see any voltage above 12 while the car is running. Pretty certain it's a bad alternator?

 

Yes, alternator can partially fail (rectifier loses part of diodes) resulting in reduced voltage/amperage output.

Mine went out at ~ 140K miles recently. Easy DIY. There's a thread on the subject.

good luck

 

Sounds like a dead alt to me as well.
DIY is pretty darn simple.

 

Changed alternator, problem solved. Thanks for the input. Seems like I can't get a break from this 07' TSX. Then again, things are failing pretty much when they typically fail, I also have around 150K miles... Guess I can't complain. So far, I've had to change:


1. steering rack (not typical)
2. front and rear motor mounts (typical)
3. AC compressor (not typical)
4. alternator (typical)
5. both lower front control arm bushings. (typical)
6. drivers side wheel bearing (typical)
7. blower motor transistor (hacked it using a wire) (not typical)
8. Serpentine belt (typical)


out of all these, the steering rack issue is what pissed me off the most. Failed at 100K both O-rings failed and lost power steering while driving. The other thing making me nervous right now is the transmission. Any data on when the transmission on these cars typically start having issues?


peace.

 

You've got a problem child there. Our 07 has 222K miles on it, and we've had to replace (other than wear and tear):

1. AC condenser (bottom rotted out)(thank you New England winters)
2.
3.
4.
5.
6.
7.
8.

 

Mines also up there in mileage (145,000) and making me nervous lol. The transmission is a concern of mine also...
You have done quite a bit more than I would think is normal to it.

 

I own an 2005 TSX and at 160k, alternator just fried over the weekend. $330 to replace with OEM. Was told that the transmission will be around the 175k-200k. Maybe it's time to upgrade to the TLX ;-)

 

FYI charging system on any automobile should be at around 14 V with the car at fast idle, a little less just idling.

 

My alternator went out at 105k. It's an easy DIY but a pain to get to the mounting bolts. Doesn't hurt to also replace the serpentine belt too.