Topic: HELP!!! Alternator not charging, tried everything

[Johny125]

I have an 07 Sky Redline with 27K miles.  The other day while driving I noticed my aftermarket voltmeter gauge was showing 12.0 volts.  Shortly thereafter, the battery light came on as the battery began to discharge.  I checked the battery and it was showing 12.0 volts with the battery indicator glowing green.  I checked the battery cables and all were in great shape.  I had earlier cleaned the ground wire on the front of the engine and it was still shiny good.  I cleaned all of the ground points I could find and cleaned them.  I checked the battery wire attached to the back of the alternator and it showed 12v with the engine off.  I suspected the alternator and replaced it with a brand new gm alternator.  To my dismay, the voltmeter still shows 12.0 with the alternator not charging.  I am considering making an appt with the dealer, but wanted to pick your brain on what else it might be.  The PCM prehaps???? Thanks in advance,

John 

[Jim]

There's a fusible link (10amp) from the starter that feeds the alternator. Run a 10 guage wire from that starter connection and see if it starts charging.

[Johny125]

Thanks Jim,  If the fusible link is burned through would I still get 12v to the alternator through the red cable attached to the back of the alternator.  I asked this because I am getting power to the alternator.  Also is the fusible link a small (possibly 14-16) gauge brown wire???  If so, there is very little room under there.

[Jim]

You could possibly be getting power by having a couple strands of wire left on the fusible link which probably wouldn't be enough to charge the battery. The red wire from the alternator is attached to the starter but it is black at the starter. Not sure why they didn't make it red....It is the 8 or 10 gauge wire.

[Johny125]

Okay, I took the Sky to the dealer today and they diagnosed that the fusible link was fried.  Total cost of repairs, $610.
Wiring harness part $252 (ouch) plus 2.0 hours labor.  How does that price sound Jim??  Thanks for your accurate diagnosis.

[Jim]

Yikes! I think I would have replaced that fusible link myself but as long as it's fixed that's all that counts. I don't know if you could find the actual fusible link but you might have found something comparable. 2 hours to R&R is probably accurate as it's not the easiest piece to get to.

[Johny125]

Not fixed YET, still waiting for the GM harness to arrive.  The fusible link is contained within the 6 feet of harness.  Of course they won't attempt to replace the link itself.  I have to buy the whole 6 ft.  I only hope it doesn't blow again.  Technician not sure why it blew in the first place.  He said it may have originated in the old alternator or maybe a short to ground on that piece of harness.  He thinks once he removes the harness he may see evidence where there may be a rub or cut on the wires which would have caused the positive to touch ground and that's what blew it.  We will see, and I will keep you posted of the results.

[Jim]

If the tech finds a chaffed area on the harness, take a picture of where it is. I  have a code p0336 right now and I'm waiting on a new sensor but can't rule out a bad wire just yet until I replace the sensor. I bought the sensor because it's cheap and since it's not the easiest spot to get to, I'm not interested in trouble shooting it without a new sensor in hand.

[Johny125]

Will do Jim!!  The new harness is not due at the dealership until Tuesday or Wednesday.  I am going to ask that the old harness be returned to me.  I will also ask the tech where on the car the wire rubbed or was cut. 

[Johny125]

Okay, I just heard back from the dealership today.  When they attempted to put the new battery-starter-alternator cable, they found corrosion on some of the connections.  They cleaned them up and all is back to great working order.   The new cable was not needed, but I still got charged from 3 hours labor, one for diagnostics and 2 for tracing and cleaning up the connections.   Thanks for all of the your input.

[elff]

Congrats.
Get out there and enjoy your car now!