Alternator or...?

An interesting drive home from the Easter celebration, to say the least. Made the trek to the City for Easter, including picking up and returning my 94 yo Mother-in-law while my the Wife rode in the kiddy seat, bad back and all. Was a gorgeous day in KC and hope all enjoyed a nice holiday. Whilst returning to our rural abode, the red screen of WARNING BATTERY GENERATOR comes up on the dash. Heart sinking moment indeed, I pull the lever to acknowledge the message, and my mind starts spinning as the barrage of questions begin flowing from my Wife. I look at the ammeter and we're above 12 volts, but definitely below the closer to 14 home for the needle. I glance again and the needle is making slow swings (about 1 volt) up and then back down. My answer at this point to the litany of questions is "Honey I don't know why". As she's whipping out the manual and searching the glossary, I'm thinking if the bearing is going out this could get ugly fast. She reads the cursory pull over and/or get the car to your Porsche dealer stuff (I'm paraphrasing here) but the one thing that did stick is the phrase loss of power steering, so without having the particulars or first hand experience under the bonnet this is telling me serpentine belt. The other good thing is Lynn hears better than a Timber Wolf so if it was the bearing she'd have already noticed it (she always announces to me the occasional ping from the motor) At this point I'm thinking the alternator is suffering electrical failure but we've got about 50 miles left, the first half on 70mph roadway, the remainder at 55. Already out of the City, and it's dusk, I think once about pulling over to let the alternator cool down, think what if won't start back up, and decide we'll prod ahead. Turn the headlights off, no appreciable change in ammeter. Turn the A/C off, no change either. About ten minutes later the warning comes up again...acknowledge...now we're below 12 volts. As we approach the town between us and home, I think of all the road construction and stop lights, and weigh these negatives against the positives of plenty of parking lots to leave the car. I make the decision to go South, by-passing town, staying on 55 mph roads, time difference is negligible...must have been another ten minutes, WARNING up again. Still below 12 and a bit lower than before. Maybe just paranoia, as it's completely dark now, but the lights seem dimmer than normal. Avoid using high beams, rounding a corner and here's two deer crossing, the second popping up causing us to brake hard and select second gear. WARNING again but at this point we're less than 15 minutes out. The wife is praising the car aloud, telling her what a faithful servant she's been and how much we appreciate her un-daunting performance. Last turn and on the home stretch, 4 miles out ABS failure warning...acknowledge look at ammeter, it's on the peg below 10 ! Air bag failure warning...acknowledge NOT good we're going down ! the center screen starts flashing on and off, on and off, finally goes off not to return. The wife is asking if she'll have to jump out of the car? (she's freaked) I tell her we'll skip the usual cool down, outside of the Garage, and I'll come to a complete stop to let her out before pulling in. At one point along the 45 minute of pucker, I thought of starting a text conversation with my mechanic, but realized my phone had crashed, hard, loosing all my contacts, not possible. Was this a costly mistake on my part? I'm hoping the car was just going through load shedding and systematically shutting off unnecessary items in order to keep moving?

Sorry to hear your ordeal. The last part of diff systems shutting down sounds pretty bad. Anyhow you can try to recharge your battery fullyor put a new battery in and start the car and see what happens. And of course it's likely your alternator is gone.

Get into the engine compartment and first check your surpentine belt. If thats ok, I would take the battery into the shop and have it tested. If that is ok, then I would go for a re-furbished alternator. Exchange my old for new which would be much cheaper than buying a new one, Change it myself and all should be back to normal. Know your radio code before disconnecting your battery. Good hunting.

Before you try an alternator, you could take a flier on the $40 voltage regulator / brushes. The drawback is to see if this part works, you need to remote the alternator and refit it. Maybe you'll get lucky, and maybe you won't. And you'll need a full battery charge.

Quotes source post: 11308707

Definitely sounds like a bad battery or alternator. I'm still amazed that as soon as something goes wrong with these cars the first thought is the IMS.

Reads like a bad alternator. The alternator was not able to supply sufficient electrical power to power the car so the battery supplied this. As the battery ran down various systems started detecting low voltage. I'm surprised the engine didn't misfire. Came upon a car with what proved to be a bad alternator and this is what it did. After various seemingly random warnings appeared the engine would then misfire and die. The tech would turn off the key let the car sit a while and then the engine would start just fine and idle but after a few minutes go through the whole process all over again. Anyhow, bad alternator is what I think it is. Get the car to a qualified shop with a description of what happened and get the problem cause id'd and fixed.

Wait..., did you loose power steering? I couldn't tell by the way it's written. If you did, than it is most definitely a serpentine belt problem- whether something else seized or it just failed is a different story. What scares me is this- when your generator light comes on AND you loose power steering.., YOU HAVE NO SERPENTINE BELT! This means from the second that warning comes on, your WATERPUMP has stopped spinning! You have zero coolant flow. The coolant removing the heat from the hotspots in the heads has no place to go. Simply watching the temp gauge isn't enough, as you are only monitoring one spot in the static system. Stop and tow the car. This is my professional advise for anyone who is experiencing this, and found this thread via search function. If you still have power steering, probably an electrical failure of the alternator. At least your motor will stay cool as your electrical potential dwindles away slowly. As a side note, Your 996 doesn't not have the ability to shutdown certain systems to maintain critical management, only the newer electronics can do that... Stuff shutting down/wigging out is exactly that- not enough power to function correctly.

In case you want to go for the Regulator: These sites reference the different part numbers and various companies offer a replacement part for the Bosch part. These companies usually only have one part number and list ALL the Bosch numbers as equivalents. Here are a few of several possible sources of information. I would like to suggest that you google the part numbers yourself to double check. I have satisfied myself but I cannot guarantee 100%. I can tell you that my car is behaving perfectly with the F 00M 145 350 part. (Ref; http://www.woodauto.com/Component.aspx?Ref=VRG46473 OR http://www.mercedesshop.com/shopforu.../t-187174.html OR http://www.jnelectric.com/bombridge....umber=F00M1453 50&manufacturer=Bosch&description=Regulator%2C+Ele ctronic ) Finding a voltage regulator Through various sources I found and confirmed that the Bosch number for the regulator in the Porsche alternator is F-00M-145-225. It would appear that this part isn�t actually listed anywhere as a separate item, although I did manage to track one down on e-bay. All is not lost though, as the same part is available under different part numbers. Various websites cross reference the above part number with the regulator for various Volkswagens from the similar years as well as Audi�s and Mercedes. For reference a commonly available part seems to be the F-00M-145-350 or F-00M-145-341 for VW, Audi, and Mercedes which fit perfectly. These sites reference the different part numbers and various companies offer a replacement part for the Bosch part. These companies usually only have one part number and list ALL the Bosch numbers as equivalents. Here are a few of several possible sources of information. I would like to suggest that you google the part numbers yourself to double check. I have satisfied myself but I cannot guarantee 100%. I can tell you that my car is behaving perfectly with the F 00M 145 350 part. (Ref; http://www.woodauto.com/Component.aspx?Ref=VRG46473 OR http://www.mercedesshop.com/shopforu.../t-187174.html OR http://www.jnelectric.com/bombridge....umber=F00M1453 50&manufacturer=Bosch&description=Regulator%2C+Ele ctronic ) I suspect that the different vehicle manufacturers insist that Bosch supply parts with a unique part number or that Bosch manufacture identical parts in different locations and assign part numbers to each.

Kind thanks for all the replies. Been a long week but battery is now fully charged. May have the time to dig into this weekend. Thanks sfv_rider and fpb111, headed to town to VW dealership to purchase a voltage regulator. They had the ignition switch electrics in stock when that failed. Worth a try. This concerns me? Our car has an aftermarket radio, suppose I'll do a search for more info. When the voltage finally pegged (low) we were literally a couple of minutes from the driveway, and under no heavy acceleration load, near coasting in if you will. ALTERNATOR bearing...I knew this was a serpentine belt so getting off the divided highway, to a secure resting place and prior to overheating may be a challenge.

+1 on the voltage regulator. When my alternator started acting up, I took it to a local place that specializes in alternators. They tested the alternator (for free!) and told me the issue was with the regulator, which I replaced. From pelican parts I bought part #000-043-206-37-M14 for $37.50 which is Bosch F 00M 144 136.