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Jake, Automotive Technician
Category: Porsche
Satisfied Customers: 3992
Experience:  Experienced collision repair technician, Pulaski Tech graduate and DSM hobbyist.
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How much does this service charge? Problem Porsche: 1999

Customer Question

How much does this service charge?
JA: I'm not sure of the exact price, but there's only a $5 deposit. The rest of the price information will be on the page I send you to.
Customer: Problem Porsche: 1999 Carrera Cabriolet, with A/C on 996 engine. Mileage is @84,000.
JA: Have you checked the Freon level?
Customer: Not an A/C problem, just giving car info. Problem: On recent start, after heavy rain, both the ABS and battery light came on. The volt meter was hovering around 12 (normally it's just below 14). Checked battery and found water around batter caused by blocked drains. Cleaned drains and dried area. Battery was showing 12.9 volts with engine off and the same with the engine on. After slow charging battery for 12 hours, rechecked system and this time when engine rpm was about 2000 rpm, voltmeter went to @14 (normal) and both ABS and battery lights went out. Allowing the engine to go to idle the voltage would drop to 12 and both lights were again on. Drove to AutoZone and had them do there thing...Battery okay, alternator check didn't work. So....Alternator? voltage regulator? water issue in front?
JA: Are you fixing your Carrera yourself? What have you tried so far?
Customer: Yes...see above
JA: Anything else you want the mechanic to know before I connect you?
Customer: Well in the early 60's worked as Porsche mechanic...As a 70+ year old and not having a clue as to electronics, I need a young brain to help me...
Submitted: 1 year ago.
Category: Porsche
Expert:  Jake replied 1 year ago.

Hey there, thanks for the question.

I assume you checked the charge rate under a full load? If so at 2000 rpms you should expect to see from 14--14.5v. At idle your readings should be close to the same.

If there was an issue with overcharging causing battery leakage or high readings at 2000rpms then I would say for certain it's the voltage regulator. At this point though just from a low voltage reading it could be the regulator or the alternator itself (brushes, bearings, etc). While the 996 engine isn't the most difficult to replace an alternator on, you can bet it will take you around 4 hours if you haven't done one before. Depending on valuable your time is to you, a rebuilt alternator or having yours rebuilt while out is probably the best bet.

Customer: replied 1 year ago.
Thank you. I have checked on the DIY for regulator & alternator replacement. It appears to me replacing the alternator is the way to go; what are your thoughts? I notice the positive cable goes to a fixture on the "firewall". There is some discoloration on the cable. Could this be something I should investigate?
Expert:  Jake replied 1 year ago.
Of course any corrosion will cause increased resistance and makes both for poor grounding and voltage loss but usually minimal. Simply test voltage at both sides of the junction to see if it's creating an issue.
Expert:  Jake replied 1 year ago.

If you have more questions though please let me know i will be happy to assist further.

If not just be sure to leave a kind rating when were done is all.